95 SC2 A/T 133K - ECTS(s) & Level Sensor - Advanced Troubleshooting Help

[cxrpsecollector]

I picked this car up for my girlfriend a few weeks ago, and given that it's 30 years old, I've been doing some work to make it (hopefully) more reliable. Previous owner said both coolant lights have been on for a while, and the gauge doesn't work.

I grabbed a bunch of parts from RockAuto, including an ACDelco sensor for the sensor, and a Wells for the gauge sender because there was no ACD/OEM version available. I ordered an SKP reservoir because I didn't want to spend $58 on the GM.

The first thing I did was a coolant system flush with Blue Devil 3-in-1. I figured I would wait to install the new parts until after the flush, so I started with removing the original reservoir and giving it a thorough cleaning (previous owner had used green coolant and I'm thinking he didn't get 100% of the Dexcool out, so there was some build up). I was able to free up the float and got it reinstalled. Despite that, the low coolant light has remained on.

Following the flush, I installed the temp sensor & sender and then refilled with straight distilled water for a final rinse. Both of the sensors I replaced were already of the brass variety, and I didn't see any corrosion in the pigtails. I was a bit disappointed to see that, in spite of everything looking good, the gauge still didn't work and the high temp light remained on.

When I got home from work last night I dug into it further. The first thing I tried was to jump the pins on the level sensor pigtail, as it's my understanding that doing so should turn the warning light off. Again, to my disappointment, the light remained.

I moved along to testing the gauge sender by checking its resistance with not one, but two meters: a Fluke and a Klein. Both meters brought further disappointment when they showed exactly zero resistance. I decided to bypass it entirely at that point, which I started by verifying the single wire had continuity to ground. I then grounded it directly, which, again, to my understanding, should have resulted in the temp gauge being pinned to hot. Once again (if you haven't noticed, this is becoming a trend) I was met with disappointment, as the gauge never moved from cold.

At the end of this debacle, I am no closer to a resolution. In fact, I'm a little more confused. What are the chances that neither circuit works when bypassed with a jumper or a direct ground? What else could be going on? All the other gauges on the dash work fine and don't randomly drop when driving or anything, so I would think the cluster would be okay? I do plan on replacing the main battery cables and refreshing all the grounds I can find, but I have exactly 0 faith that will make any difference.

Would appreciate any help!

 

[Derf]

I have a 95 SC2.

I highly suggest before sinking a bunch of money into this vehicle that you do a lend a tool at AutoZone or similar for a compression tester and check the compression of all four cylinders. If it's too low, it's really not worth the investment which is going to add up quickly. Please report back here with the measurements.
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The cluster connects to the rest of the car's electronics via a ribbon cable up near VIN plate under top dash panel ( do not touch it yet). The contacts on both the ribbon coming from the cluster and where the ribbon attaches to the car get corroded some of the electronics cease to function. I will get to the process of taking the top dash off and removing the ribbon cable without destroying too much.

Things can and do go wrong with the electronics for the dash, pretty much all of which are integrated into an old fashioned circuit board with traces. Resistors burn out, capacitors go bad, grounds go bad, etc, so you can lose partial functionality on the dash for different gauges.

Ects: always replace the ects pigtail when you replace the ects. I'm talking about the two wire ects. That's the one that goes to the PCM and is used to determine the air fuel mix.

The single wire tep sensor drives only the dash gauge. 95 was the last year of this configuration. 96 and up have only a two wire sensor. If you were measuring across the two wire ects, it would have no effect on the reading on the dash since that comes from the one wire device.

However, the low coolant light is controlled off of the resistance of the two wire device.. it's very easy when trying to measure the resistance across the two men to have your probe tips touch, therefore giving you a zero reading. You're not the first and you won't be the last. It happens. I'm assuming you were just trying to read the sensor not attached to anything

You won't see the corrosion on the pigtail but it's there. Replace it as insurance that the contacts are not shorting.

In theory, a low resistance for the ECTS, say 300 ohms corresponds to the temperature of the coolant being very hot say 195.

I believe a reading of like 2500 ohms corresponds to something around 50 F.

If the circuit goes open circuit, that's the equivalent of infinite resistance and the PCM interprets that situation as the coolant temperature being minus 28F.. PCM never throws an error in this situation because mine is 28 somehow is a valid in range reading. Suppose if you're driving in Northern Canada....

If the circuit shorts, that's the equivalent of very very very very little resistance, so the PCM thinks the coolant is hot enough to be overheating. The the over temperature light should turn on and the cooling fan under the hood should also turn on and stay on until that resistance drops to a normal level. If it's shorted, that will never happen so whenever the vehicle is on, that fan should be running. If it isn't, that's another issue to deal with..Later.

The switch in the reservoir is not a level switch per se.

It's a pressure switch and is extremely sensitive to the head pressure of the liquid in the reservoir. Obviously you have to get the sensor unstuck but it doesn't always work afterwards. As a last ditch effort, take it off the vehicle and fill it with a solution of very hot water with some Dawn dish detergent. Try not to shake it too much or you will die before I ever rinsing all of the bubbles out. Just let it sit for a few hours, rinse, then repeat. Make sure you get all of the soap out of there because if there's any left, if it gets into the cooling system of the car, it will start to foam all over the place when it hits the water pump.

Yes he above does not work, bite the bullet and buy a dorman replacement reservoir. You cannot buy the switch separately.

The car uses traditional green coolant, not the orange Dex cool. I'm not sure what you found in there, but it should have been green and you should refill it with green 50/50.

Make sure you remove the block drain plug to get off the coolant out. I believe it's on the driver's side. Soak it first with blaster. Do not break this off. It's probably never been off since the factory so be very careful with it.

I've also had the low coolant light flash for three or four minutes after starting in the morning in the winter. I believe this is because the coolant contracts . Once the car gets the closed circuit operation, the light goes off.

I don't remember if the coolant tank sensor when the tank is full is normally open or normally closed. I would think it would be normally closed but I will look it up tomorrow.

Get a hold of a copy of the Chilton 91 to 93 manual. You can find it on eBay. Have used the wiring diagrams in that book for the 93 all the way up to 97 for which they are pretty close. Except for the factory service manuals, the schematics in that book are the best you will find for the 95, or should I say the 93. Without seeing out all of this is connected, it will take you hours upon hours to figure out what's going on versus what should be going on.

Monitor the oil level very very very carefully. These engines have a nasty habit of burning oil at higher mileages, especially if the oil changes have not been frequent enough. You should be changing once every 3,000 maximum. The crank case holds four quarts total. Do not let it get down more than half a quart.

That's all for now. I need to go back to sleep

 

[cxrpsecollector]

I have a 95 SC2.

I highly suggest before sinking a bunch of money into this vehicle that you do a lend a tool at AutoZone or similar for a compression tester and check the compression of all four cylinders. If it's too low, it's really not worth the investment which is going to add up quickly. Please report back here with the measurements.

I know it burns oil, which I'm hoping to at least lessen via a Berryman B12 cylinder soak. After that, I'll check compression, but I'm hoping to only need the car for a year, maybe a year and a half.

The cluster connects to the rest of the car's electronics via a ribbon cable up near VIN plate under top dash panel ( do not touch it yet). The contacts on both the ribbon coming from the cluster and where the ribbon attaches to the car get corroded some of the electronics cease to function. I will get to the process of taking the top dash off and removing the ribbon cable without destroying too much.

Things can and do go wrong with the electronics for the dash, pretty much all of which are integrated into an old fashioned circuit board with traces. Resistors burn out, capacitors go bad, grounds go bad, etc, so you can lose partial functionality on the dash for different gauges.

I watched richpin's video of the cluster removal, while a bit tedious with the amount of fasteners GM used, it doesn't seem like the most daunting task. Regardless, if possible, I wouldn't mind avoiding it. I went through the engine bay last night and cleaned up a few of the grounds that were questionable. I put new ends on 4 of the smaller ground wires and shrink wrapped them to prevent moisture intrusion. Unfortunately, I did notice corrosion creeping up in the wires. If the compression test comes back good, I may put a bit more effort into tracing those grounds back to clean copper and extending them back. Maybe even add a ground bus. I know the battery cables should be replaced as well, as they're quite stiff and the ends are open to the elements due to the variety of ring terminals they used.

Ects: always replace the ects pigtail when you replace the ects. I'm talking about the two wire ects. That's the one that goes to the PCM and is used to determine the air fuel mix.

Looking around at replacement pigtails I am only seeing the 2-wire version. Due to the socket of the sender ("female") being different than the sensor ("male"), I am guessing the connector itself is different as well. I would go look right now, but I'm at work. If it is indeed different, and I can't find a 1-wire connector, would it be possible to just replace it with a second sensor, rather than a sender, and then use another 2-wire harness with the other wire snipped off? Do you know if the resistance values between the two are the same?

The single wire tep sensor drives only the dash gauge. 95 was the last year of this configuration. 96 and up have only a two wire sensor. If you were measuring across the two wire ects, it would have no effect on the reading on the dash since that comes from the one wire device.

However, the low coolant light is controlled off of the resistance of the two wire device.. it's very easy when trying to measure the resistance across the two men to have your probe tips touch, therefore giving you a zero reading. You're not the first and you won't be the last. It happens. I'm assuming you were just trying to read the sensor not attached to anything

The single wire was the one I was messing with last night. I removed it and threw it in my vise so I could make sure that I was getting steady contact on the pins without crossing the leads. I had to have checked it dozens of times with both meters. We'll see what the replacement from RockAuto tests at; not sure when that's supposed to ship. I have yet to pull the 2-wire to measure resistance on that, I may do it tonight, provided it isn't raining.

Are you saying the low coolant light is also tied into the 2-wire temp sensor, or am I misunderstanding? Is that why the low coolant light didn't go off when I put a jumper wire across the tank sensor connector?

In theory, a low resistance for the ECTS, say 300 ohms corresponds to the temperature of the coolant being very hot say 195.

I believe a reading of like 2500 ohms corresponds to something around 50 F.

If the circuit goes open circuit, that's the equivalent of infinite resistance and the PCM interprets that situation as the coolant temperature being minus 28F.. PCM never throws an error in this situation because mine is 28 somehow is a valid in range reading. Suppose if you're driving in Northern Canada....

If the circuit shorts, that's the equivalent of very very very very little resistance, so the PCM thinks the coolant is hot enough to be overheating. The the over temperature light should turn on and the cooling fan under the hood should also turn on and stay on until that resistance drops to a normal level. If it's shorted, that will never happen so whenever the vehicle is on, that fan should be running. If it isn't, that's another issue to deal with..Later.

I plan on ordering some cheap amazon resistors as a sanity check to make sure my meters are actually reading properly, and then I can jumper it across the 2-wire connector as well. When I get home tonight, I'll take a piece of wire and jump it to verify that the e-fan is, or isn't, functioning.

The switch in the reservoir is not a level switch per se.

It's a pressure switch and is extremely sensitive to the head pressure of the liquid in the reservoir. Obviously you have to get the sensor unstuck but it doesn't always work afterwards. As a last ditch effort, take it off the vehicle and fill it with a solution of very hot water with some Dawn dish detergent. Try not to shake it too much or you will die before I ever rinsing all of the bubbles out. Just let it sit for a few hours, rinse, then repeat. Make sure you get all of the soap out of there because if there's any left, if it gets into the cooling system of the car, it will start to foam all over the place when it hits the water pump.

Yes he above does not work, bite the bullet and buy a dorman replacement reservoir. You cannot buy the switch separately.

The car uses traditional green coolant, not the orange Dex cool. I'm not sure what you found in there, but it should have been green and you should refill it with green 50/50.

Make sure you remove the block drain plug to get off the coolant out. I believe it's on the driver's side. Soak it first with blaster. Do not break this off. It's probably never been off since the factory so be very careful with it.

I've also had the low coolant light flash for three or four minutes after starting in the morning in the winter. I believe this is because the coolant contracts . Once the car gets the closed circuit operation, the light goes off.

I don't remember if the coolant tank sensor when the tank is full is normally open or normally closed. I would think it would be normally closed but I will look it up tomorrow.

When I do the final drain and fill, I'll throw the new reservoir on. Hopefully the SKP will suffice as I really don't want to deal with another RockAuto return. I'll be honest, I don't even know where I saw that the 95s took Dexcool, but everything definitely says to use the standard green. I'll return it and grab the right stuff tomorrow.

Get a hold of a copy of the Chilton 91 to 93 manual. You can find it on eBay. Have used the wiring diagrams in that book for the 93 all the way up to 97 for which they are pretty close. Except for the factory service manuals, the schematics in that book are the best you will find for the 95, or should I say the 93. Without seeing out all of this is connected, it will take you hours upon hours to figure out what's going on versus what should be going on.

I have what is probably the last revision of both the Chilton and the Hayne's manuals. Is the 91-93 superior in regard to the diagrams?

Monitor the oil level very very very carefully. These engines have a nasty habit of burning oil at higher mileages, especially if the oil changes have not been frequent enough. You should be changing once every 3,000 maximum. The crank case holds four quarts total. Do not let it get down more than half a quart.

I think we've driven the car a total of 50 miles or less so far, but I am definitely cognizant of checking the oil level. I have seen some people report a loss of 1 quarter every 300 miles. I'm hoping that #1: this one isn't that bad, and #2: it can be partially remediated with the cylinder soak. Wish me luck!

 

[Derf]

If you don't do an initial wet and dry compression test, how will you know if the soak improved anything?

I strongly advise you drive the vehicle long enough as is to figure out the oil consumption amount. 1 quart per 300 miles is a rebuild. Besides the oil control rings, the valve guide seals go bad on this engine, allowing massive amounts of oil into the cylinders. You can soak till the cows come home, but you will not overcome the valve guide seal issue without at least a top end refresh.

You said you were messing with the 1 wire temp sender but measuring across the two pins. Confused. The one wire sensor has a single lead and the ground is provided by the body of the sensor. There is only one pin. If you have it out of the car, you would have to measure between the one pin and the outer threaded portion of the sensor to get a resistance measurement. I have no idea what the range is for this sensor as a function of temperature. The connector is generic and easy to replace. The connector I referenced replacing is for the two wire ects, when the originals failed, it was a different design and coolant could get into the electrical connection and mess up the reading. Now that it is all brass, that can't happen, but most people never changed the pig tail so it likely has residual coolant on the inside of it. If it doesn't, it's 30 years old and cheap to replace to remove the effect of any corrosion on the measurement.

The ects and tank sensor are completely separate circuits. Apologies if my wording was confusing.

I suspect the issue with the temperature gauge will be found on the circuit board in the cluster or at the ribbon connection. If you'd like to avoid removing it that's up to you, but my guess is you'll find no voltage getting to the gauge even after replacing the sender. Hoping I'm wrong.

91 to 93 Chilton wiring diagrams are superior using the 93 diagrams up to about 97 which includes 95. The other books list General circuits that supposedly cover 91 to 02. Diagrams changed as the design changed in 98 especially with the clusters.
One of the two later chilton books has a nice multi-page layout for the general connections of different devices with regards to wiring. But it is not detailed enough in practice like the 91 to 93 diagrams are.

_____________

The initial compression test and knowing the oil consumption rate will tell you whether or not this entire project involves a rebuild. Since you only need it for a year, doesn't sound like you would pursue that.

If you don't already have the issue of misfires, once the compression gets low enough you will.

All of that oil is wrecking your cat con and likely plugging it up.

You can put a lot of money into this vehicle with regards to sensors, connectors, and get everything working just as it should, except that the engine May simply be worn out. Once you get to that level of oil consumption, it only takes forgetting to put oil in a few times at a fill up to get this engine, as tired as it is, to throw the chain, or spin a bearing. These engines love to burn exhaust valves. I've driven on three cylinders for 9 months. It's just not fun and you can't do it on the highway.

In no way am I trying to be a dick, but until you have oil consumption data and the initial compression test data posted, I can't see both of us devoting a ton of time to trying to bring this back in an illogical manner.

I've been a moderator over at saturnforum.com for almost 20 years running. I've had at least one S car in my driveway since 92.

I'm more than happy to help you bring this back to its former glory, but we have to be smart about the approach. If you only need it for a year, then there are probably six core things we need to make sure our functioning or get them functioning. But not knowing what you're starting with will not get you very far. If it makes more sense to drive into the ground, then we fix enough to do that.

Don't know until you assess the compression and oil consumption.

Would it be nice if you have everything working on this car while you drive it into the ground? Of course. Because you're a perfectionist. Ask me how I know.
But you need the reality check of knowing what you're starting with before you burn a bunch of cash on the wrong cause.

Compression test is half an hour of your time.
Oil consumption is driving the vehicle around and checking.

Please reconsider and let me know.

 

[Derf]

Well,

It seems you have decided to pursue this without my further assistance. It saddens me, as I pride myself on getting every single Saturn back up to snuff and happily on the road. But I can't make you do anything that you do not wish to do. I can only advise from experience and try to keep money in your pocket where appropriate.

I was remiss in giving you a link to a wonderful resource.

Charm.li is an online resource that has factory service manual content from many many manufacturers, covering many many years. This includes all of the Saturn line. As you will see when you visit it it is sorted initially by manufacturer, then year, then model. So everything for the S cars is there. I have not explored all of it and some of it is less than detailed, but that is in line with it being a factory service manual.

I am always available to assist with any issues that you come across on your journey. I don't play keep away with the information. The only thing I request, emphasis on the word request, is that we begin from a known baseline and go from there.

This approach has evolved from several situations for which I have devoted hundreds of hours with individual vehicles and users, only to find that the most basic information not provided has made the entire journey pointless.

You're not being singled out. I'm trying to help with an initial assessment before diving in. Nothing more nothing less.

Peace

Derf

 

[cxrpsecollector]

Well,

It seems you have decided to pursue this without my further assistance. It saddens me, as I pride myself on getting every single Saturn back up to snuff and happily on the road. But I can't make you do anything that you do not wish to do. I can only advise from experience and try to keep money in your pocket where appropriate.

I was remiss in giving you a link to a wonderful resource.

Charm.li is an online resource that has factory service manual content from many many manufacturers, covering many many years. This includes all of the Saturn line. As you will see when you visit it it is sorted initially by manufacturer, then year, then model. So everything for the S cars is there. I have not explored all of it and some of it is less than detailed, but that is in line with it being a factory service manual.

I am always available to assist with any issues that you come across on your journey. I don't play keep away with the information. The only thing I request, emphasis on the word request, is that we begin from a known baseline and go from there.

This approach has evolved from several situations for which I have devoted hundreds of hours with individual vehicles and users, only to find that the most basic information not provided has made the entire journey pointless.

You're not being singled out. I'm trying to help with an initial assessment before diving in. Nothing more nothing less.

Peace

Derf

Apologies man, I haven't had a chance to look at it again. I worked this past weekend and I'm on 12.5 hour shifts on the weekdays. On top of that, it started raining Tuesday and isn't supposed to stop until Friday afternoon. When I'm able to get back to it, I'll definitely update.

I have seen the charm.li site, though admittedly, reading 90s GM electrical diagrams isn't my strong suit. I am only slightly more familiar with industrial prints (strong emphasis on slightly.)

 

[Derf]

I thought you were ditching me as a resource.

I tend to misinterpret silence. You will get to it when you get to it.

 

[cxrpsecollector]

If you don't do an initial wet and dry compression test, how will you know if the soak improved anything?
I strongly advise you drive the vehicle long enough as is to figure out the oil consumption amount. 1 quart per 300 miles is a rebuild. Besides the oil control rings, the valve guide seals go bad on this engine, allowing massive amounts of oil into the cylinders. You can soak till the cows come home, but you will not overcome the valve guide seal issue without at least a top end refresh.

You said you were messing with the 1 wire temp sender but measuring across the two pins. Confused. The one wire sensor has a single lead and the ground is provided by the body of the sensor. There is only one pin. If you have it out of the car, you would have to measure between the one pin and the outer threaded portion of the sensor to get a resistance measurement. I have no idea what the range is for this sensor as a function of temperature. The connector is generic and easy to replace. The connector I referenced replacing is for the two wire ects, when the originals failed, it was a different design and coolant could get into the electrical connection and mess up the reading. Now that it is all brass, that can't happen, but most people never changed the pig tail so it likely has residual coolant on the inside of it. If it doesn't, it's 30 years old and cheap to replace to remove the effect of any corrosion on the measurement.

The ects and tank sensor are completely separate circuits. Apologies if my wording was confusing.

I suspect the issue with the temperature gauge will be found on the circuit board in the cluster or at the ribbon connection. If you'd like to avoid removing it that's up to you, but my guess is you'll find no voltage getting to the gauge even after replacing the sender. Hoping I'm wrong.

91 to 93 Chilton wiring diagrams are superior using the 93 diagrams up to about 97 which includes 95. The other books list General circuits that supposedly cover 91 to 02. Diagrams changed as the design changed in 98 especially with the clusters.
One of the two later chilton books has a nice multi-page layout for the general connections of different devices with regards to wiring. But it is not detailed enough in practice like the 91 to 93 diagrams are.

_____________

The initial compression test and knowing the oil consumption rate will tell you whether or not this entire project involves a rebuild. Since you only need it for a year, doesn't sound like you would pursue that.

If you don't already have the issue of misfires, once the compression gets low enough you will.

All of that oil is wrecking your cat con and likely plugging it up.

You can put a lot of money into this vehicle with regards to sensors, connectors, and get everything working just as it should, except that the engine May simply be worn out. Once you get to that level of oil consumption, it only takes forgetting to put oil in a few times at a fill up to get this engine, as tired as it is, to throw the chain, or spin a bearing. These engines love to burn exhaust valves. I've driven on three cylinders for 9 months. It's just not fun and you can't do it on the highway.

In no way am I trying to be a dick, but until you have oil consumption data and the initial compression test data posted, I can't see both of us devoting a ton of time to trying to bring this back in an illogical manner.

I've been a moderator over at saturnforum.com for almost 20 years running. I've had at least one S car in my driveway since 92.

I'm more than happy to help you bring this back to its former glory, but we have to be smart about the approach. If you only need it for a year, then there are probably six core things we need to make sure our functioning or get them functioning. But not knowing what you're starting with will not get you very far. If it makes more sense to drive into the ground, then we fix enough to do that.

Don't know until you assess the compression and oil consumption.

Would it be nice if you have everything working on this car while you drive it into the ground? Of course. Because you're a perfectionist. Ask me how I know.
But you need the reality check of knowing what you're starting with before you burn a bunch of cash on the wrong cause.

Compression test is half an hour of your time.
Oil consumption is driving the vehicle around and checking.

Please reconsider and let me know.

I was able to do a little bit over the past weekend, which included a compression test. Given that the spark plugs appeared to have been dropped directly into a jug of oil, I don't think there was much of a chance to get a dry compression reading. I'm honestly shocked that they were able to spark at all. With that in mind, assume the following values were obtained from a wet test, on a cold engine. I performed 2 tests on each cylinder to verify repeatability. I should note that I forgot to hold the gas pedal down to open the throttle body during testing, though I don't know how much of a difference that actually makes. If it's truly more accurate, I'll gladly take the extra 10 minutes to do another.

Cylinder 1: 180
Cylinder 2: 120
Cylinder 3: 170
Cylinder 4: 190

Cylinder 2 is the obvious outlier, and I am not excited about the amount of oil on the plugs either. Because I already plan on replacing the valve cover gasket, I went ahead and ordered some valve seals that I'll throw in at the same time.

Regarding the coolant sensors, you are correct, I was measuring the gauge sensor wrong. Measuring across the two pins read nothing, but measuring from each pin to the sensor body yielded the expected resistance values, which continued to lower the longer my body heat warmed it. After confirming that it's operating as intended and I'm just an idiot, I reinstalled it.

At the same time, I put the new coolant expansion tank on.

As you have likely guessed already, neither of those things made any difference. I did not have time to cut and splice the new connector ends on for the temp sensors, however, with the new tank / level sensor still failing to read, I'm thinking it's going to be a cluster problem.

 

[Derf]

To get meaningful readings, you need the engine to be at operating temperature and you must have it atwide open throttle. It can make a tremendous difference depending on what is right or wrong with the cylinders.
You need to pull the fuel injector fuse before I compression testing so that it remains dry and you're not trying to compress gasoline while doing the test. Make sure the plugs are dry after you turn off the engine and operating temperature. Pull them and dry them off.

Hopefully you are using a screw in compression tester not the one that you just hold.

Compression on a new or freshly rebuilt Saturn dohc for this vehicle is 210 to 225 (memory). The service limit is stated as 180. I've actually driven one down in the 140s and it Sparks fine. No real power and consumed six quarts of synthetic every 3K. OBD1 has no misfire code and I don't think PCM has a misfire counter. At least not accessible without something like a tech II. Number two is indeed disappointing and might be part of the reason the previous owner past the vehicle on to someone. For the mileage the others are not too bad and there's no sign of head gasket issues from those readings.

The wet test will likely confirm that it is a compression ring issue with number two. All of the oil control rings are frozen up and varnished. If you pull the head you can re-ring the Pistons fun fun fun. But once you get to that stage most people just take the whole thing apart overbore the cylinders, replace with oversized Pistons with oversized rings and rebuild the entire top and bottom of the engine. I have gotten about 185k out of each of my mid-90s Saturns with good maintenance and proper oil changes. Lost a cylinder on one of them at 185, never investigated just put a reman in. Tried to stretch and oil change and was rewarded with a valve through the piston on my other one.

You should be able to listen to the exhaust note to be able to determine whether the engine is firing evenly or if it is missing.

As for the ects pigtail, it really needs to be done before judging everything else. If nothing else it should Ensure that your cooling fan comes on. I don't believe the ects temperature sensor and the reservoir sensor are in the same circuit, so one should not affect the other.

I have not looked back through the posts, but if this car sad for a while, it is possible that critters may have gotten to some of the wiring as they like the insulation taste. You should be able to Short the pigtail with it removed from the sensor and see if the light goes out on the dash. I believe the sensor is normally closed so shorting it should turn off the light. Like you said it may be a cluster problem but it is also pretty much direct wire run to the fuse box.

I'm going to say this before I forget. When your car has 30 years on it the grounds are not necessarily still grounded as they were when they left the factory. Ground connections get corroded, individual wires in splice packs become ungrounded, traces on circuit boards become ungrounded. So when you are doing electrical troubleshooting, just because you don't see the voltage you are expecting, it doesn't mean necessarily that the line on which the voltage should be present is damaged. If the circuit is missing its ground, it's not a complete circuit and you will see exactly the same on the meter. So don't trust that the ground connections in your circuits are necessarily ground when you come across issues. Check the grounds.

Also, after 30 years, the connections from the fuse block to the power distribution wires underneath can have corrosion build up, as can the instrument panel junction box. Don't go there unless you have to but it does happen.

Sorry for the wandering but it's 5:00 I haven't slept much and there are things running through my head that if I don't put them down somewhere will be gone in 5 minutes.

Good morning / good night

 

[cxrpsecollector]

To get meaningful readings, you need the engine to be at operating temperature and you must have it atwide open throttle. It can make a tremendous difference depending on what is right or wrong with the cylinders.
You need to pull the fuel injector fuse before I compression testing so that it remains dry and you're not trying to compress gasoline while doing the test. Make sure the plugs are dry after you turn off the engine and operating temperature. Pull them and dry them off.

Hopefully you are using a screw in compression tester not the one that you just hold.

Compression on a new or freshly rebuilt Saturn dohc for this vehicle is 210 to 225 (memory). The service limit is stated as 180. I've actually driven one down in the 140s and it Sparks fine. No real power and consumed six quarts of synthetic every 3K. OBD1 has no misfire code and I don't think PCM has a misfire counter. At least not accessible without something like a tech II. Number two is indeed disappointing and might be part of the reason the previous owner past the vehicle on to someone. For the mileage the others are not too bad and there's no sign of head gasket issues from those readings.

The wet test will likely confirm that it is a compression ring issue with number two. All of the oil control rings are frozen up and varnished. If you pull the head you can re-ring the Pistons fun fun fun. But once you get to that stage most people just take the whole thing apart overbore the cylinders, replace with oversized Pistons with oversized rings and rebuild the entire top and bottom of the engine. I have gotten about 185k out of each of my mid-90s Saturns with good maintenance and proper oil changes. Lost a cylinder on one of them at 185, never investigated just put a reman in. Tried to stretch and oil change and was rewarded with a valve through the piston on my other one.

You should be able to listen to the exhaust note to be able to determine whether the engine is firing evenly or if it is missing.

As for the ects pigtail, it really needs to be done before judging everything else. If nothing else it should Ensure that your cooling fan comes on. I don't believe the ects temperature sensor and the reservoir sensor are in the same circuit, so one should not affect the other.

I have not looked back through the posts, but if this car sad for a while, it is possible that critters may have gotten to some of the wiring as they like the insulation taste. You should be able to Short the pigtail with it removed from the sensor and see if the light goes out on the dash. I believe the sensor is normally closed so shorting it should turn off the light. Like you said it may be a cluster problem but it is also pretty much direct wire run to the fuse box.

I'm going to say this before I forget. When your car has 30 years on it the grounds are not necessarily still grounded as they were when they left the factory. Ground connections get corroded, individual wires in splice packs become ungrounded, traces on circuit boards become ungrounded. So when you are doing electrical troubleshooting, just because you don't see the voltage you are expecting, it doesn't mean necessarily that the line on which the voltage should be present is damaged. If the circuit is missing its ground, it's not a complete circuit and you will see exactly the same on the meter. So don't trust that the ground connections in your circuits are necessarily ground when you come across issues. Check the grounds.

Also, after 30 years, the connections from the fuse block to the power distribution wires underneath can have corrosion build up, as can the instrument panel junction box. Don't go there unless you have to but it does happen.

Sorry for the wandering but it's 5:00 I haven't slept much and there are things running through my head that if I don't put them down somewhere will be gone in 5 minutes.

Good morning / good night

It is indeed a screw in style compression tester, and I forgot to mention, but I did clean the plugs and pull the injector fuse for the test. I'll do another at some point, maybe this weekend if I have time before or after work, and I'll be sure to have it at WOT.

Not sure how long it sat, or if it sat at all. I have to imagine that it did at some point because the underbody rust isn't bad at all for a 30 year old Michigan car. But that's assuming that it's been in Michigan the whole time.

I refreshed the grounds I was able to find on the driver side of the engine bay, but I have yet to install new battery cables. In the meantime, I found the ground distribution diagram and plan to refresh the others as time allows. On the ones I've already done, there was internal oxidation on all the smaller gauge ground wires, but it wasn't like the copper was turning green, it was just a bit darker than bare copper. After stripping the insulation, I cleaned the individual strands with some emery cloth before crimping new terminals on, and they cleaned up quite easily. Regardless, I would like to find where the nice shiny copper begins and extend from there. Then again, maybe after 30 years the insulation has degraded to the point where all of the wires are oxidized? I hope not.

Here's to hoping I don't have to dig into the fusebox or cluster. Fingers crossed.

 

[Derf]

Where are you located?