Saturn SL2...... Biggest mystery in history

i have a nice little saturn sl2, automatic, 160k miles that was owned by an elderly couple that towed it behind an RV, it has the factory hooks on it. the little booger runs like a top i love it. the owners took good care of the fluids but they didnt really keep up the sensors.

however, i am here to be amongst the greatest minds in the entire universe because theres a prob i cant figure out.

on acceleration the motor stumbles and hesitates. also, when i start to warm it up in the morning it only get to a quarter up the temp gauge. and also i still have the reverse slam. although it seems less since i torqued the output shaft

i have re-torqued the outshaft and it was already good and changed fluid & filter for the trans.
ac delco water pump.

i put 2 different thermostats in it because it didnt fix the prob the first time.

i put an AC delco water pump on it

upper and lower radiator hoses. and i used the orange coolant by zerex.

crank position sensor, throttle position sensor, coolant temp sensor and all the pcv valves and stuff like that.

the wires look kinda old, the plugs look kinda old and the OBD2 says it has a P0302 cylinder misfire on#2 cylinder.

the thing about the car not warning up seems to defy physics i dont know what to think of that

 

Is the car not warming up, or is a sensor telling you through a dashboard gauge via the pcm/bcm (what year is this) that the car is not warming up?

0) do a loan a tool from AutoZone or similar and measure the wet and dry compression across all four cylinders. Remember to remove the fuel injector fuse to keep from getting gas in the cylinders.

We want to find out if your cylinder 2 misfire is a deal breaker or something easily fixed.

1) If you want to know the temperature of the coolant in the head (according to the ECTS), go and purchase an obd2 scanner. Does not have to be high-end as the additional information available through the diag port is pretty darn small, so it's not worth getting a scanner with advanced diagnostics unless you will use it on other vehicles.

2) please tell me you did not use a motorad thermostat. Mine came in an ACDelco box. POS didn't last 3 hours. What temperature thermostats did you use?

3) where did you source your ECTS from?
The answers AutoZone, O'Reilly's, advanced, carquest are incorrect. Half of their electrical parts are DOA.

NAPA, RockAuto.com, GM parts houses are the right answer.

4) If you can, obtain a Delphi brand ECTS, all brass construction AND The wiring harness pigtail with the connector on the end. The contacts corrode and the wires start to fracture where they pass through the top of the connector.
*Get the pigtail*
Why does this matter? Because If the PCM cannot obtain a reading across the ECTS, it deduces that the coolant temperature in the head is -40. Constantly. Also, the ECTS changes resistance with temperature. Corrosion can add significant resistance to this circuit, making it look as though the reading is a higher resistance than it actually is. Higher resistance equals colder temperature. Very common point of failure.

This leads to difficult starting, crap gas mileage, and hesitation upon acceleration in the neighborhood of 2000 RPM, among other things like running really rich.

5) plugs
Pull all the plugs and inspect. What makes number two plug different?

Use ONLY NGK 5643 copper OE plugs. Engine was designed for these plugs/plugs were designed for this engine. Gap at zero point four zero. They come larger in the box. The gap that is.

 

To clarify my statement, you need to purchase a scanner not a code reader. A code reader simply reads the basic OBD2 codes through the diagnostic port.

A scanner interacts in both directions by reading information and codes, and has the capacity to send information and codes like clear all existing codes, to the vehicle. Make sure you get one, a scanner, that can also talk to the ABS, SRS BCM, systems. The body control module codes get stored, as do the ABS and SRS codes, but they do not light the service engine soon light so you don't know that they are there unless you scan with a capable device

 

its a 1997 sl2. and yep i changed the coolant temp sensor. most of the parts were ac delco

 

Weird. Can't see your reply.

You said you replaced the ECTS.
Didn't say if you checked compression
Didn't say you replaced the pigtail.
Didn't say if you read real time data w scanner to see if ECTS is reading correctly
Didn't say if you replaced the plugs w OE NGKs

I guess that's my contribution

 

but i did say the things i did replace. do ya really need me to list everything i didnt replace?

 

its actually not warning up. i can let it idle 10 minutes and it only warms up .25 of the way. and many times even if i drive it then it still wont heat up. i got ac delco plugs because thats what the plugs were when i searched for AC41-627. however the plugs that are in it are the NGK. so i suspect the plugs are original.

i just bought the plugs and some denso wires and i got both the coil packs to replace them to. but yea i cant figure out why it wont warm up. seems to defy physics haha

 

AC41-627

If you purchased those off the guy from eBay, go exercise your 100% return guarantee.
It's impossible for those plugs to be the correct plugs for both the SL1 SOHC and the SL2 DOHC. The OEM plugs are different between the two engines, and so worthy aftermarket ones. This person either has no idea that they are different engines or is just an ass. But that listing is incorrect. I don't know what those plugs are supposed to be put into, and frankly I don't have the desire to wade through the net to find out.

Information on the correct OEM plugs is in my message above.

I asked some simple questions in my first reply. You didn't provide answers to certain things I asked, so I pointed it out. Your response? Do I have to tell you everything I didn't replace?

No, you don't. That's why I asked the specific questions I did. Most of which you still have not answered.

I provided you a summary of what I would do to diagnose the vehicle. Can't really tell what if any of it you performed.

I reread your first post. You replaced the water pump.

Did you flush the cooling system before refilling it with coolant? You may have a blockage or partial blockage somewhere in the cooling system. This would prevent proper flow of coolant.Since the ECTS reading is taken from the cylinder head, If the coolant isn't flowing properly, the temperature of the coolant in the vicinity of the ECTS does not represent the true coolant average temperature. You get an artificially low reading.

I would think if the engine continued to run, enough heat would be built up in the engine with the thermostat closed to overheat but you don't see that, do you.

If the ECTS is to but you believed, then your thermostat never opens. So what does the ECTS read

Oh, I mentioned earlier to get a scanner and find out. I don't see any indication that you did that. Nor do I seen indication that you replaced the pigtail. It'll be very clear with the scanner whether the ECTS is reading properly or not. Just compare it before you even start the car with the intake air temperature. They should be within a few degrees of each other. Then watch it go up as the vehicle runs. If it doesn't go up, then you like we have a blockage. It starts out at a whack low temperature, either the sensor or the wiring circuit is open.

Not much more I can say that I haven't already repeated.

I've given you my advice
some of it twice
Not gonna be thrice

Oh, is your serpentine belt loose and not spinning the water pump properly? That will contribute to reduced flow in the cooling system. I'm thinking the previous owners probably never changed the antifreeze and if it was sitting there in the car for long periods of time, stuff deposited in place.

In closing, the stock NGK plugs are 36,000 mi plugs. If you have 36,000 mi plugs in that engine with 160,000 mi on it, maybe you should replace those with NGK 5643s

Good luck.

 

Couldn't stand the suspense.
Multiple listings on the internet for 41-627.

SOHC plus DOHC.
FLAT OUT INCORRECT.

Use any site's does this fit tool and you'll find this plug is specifically for the SOHC/SL1.

You can teach dumb but you can't fix stupid.

 

we seem to be misunderstanding. i have only done the obd2. im not mentioning that i didnt scan because i havent scanned it. i have also not mentioned that i havent replaced the brakes because i have not in fact replaced the brakes. see where im going with this? i have listed everything i havedone. if i have not said i have done it that means i havent did it yet.

here is a list of things i havent done.
havenmt put snow tires on yet.
havent replaced brakes.
havent replaced rotors.
i have waxed the paint yet.
i havent replaced the pistons.
i havent replaced the rings on the pistons.
i havent replaced any valves.

those are things i have not said i have done because i havent done them. the list is very very much longer but it will take about a week for me to type it all.

thanks for the advice on the plugs. the plugs you mentioned are actually in the car and they look to me like they easily have been in there since the car was new.

this is the guy on ebay selling the wrong plugs https://www.ebay.com/itm/303177761896

 

well im not sure if im stupid or not but i literally read it out of the owners manual. i would provide a pic but im not crawling under my desk to hook my phone up. i hope you and yours have a great holidays season

 

And you as well.

I've been at this (moderator at saturnforum.com) for over 20 years. I make suggestions based on the info made available to me.

I asked if you had checked certain things...yet.
They were suggestions.
When you respond with no reference to most of the "have you checked this" there is no way for me to determine what progress has been made if any.

Most people simply say "I'm getting to that this weekend." You dance around it with no indication.

It's common courtesy.

I take a genuine interest in every post.
I try to track people's progress to keep them motivated.
If that's not for you, that's fine.

I'll wait for your updates. At least now i know now that you've communicated it.

99% of the people who behave this way never accept any of the advice they are supposedly posting to receive. I don't spend any more time on those.

If you're serious I'll try to help.

As for the plugs, i believe the plugs for both SOHC and DOHC are listed in the owner's manual. This plug is listed for the SOHC.

If it's not the owner's manual that came with the car, then it's not the owner's menu

 

the only thing i can think of is that the engine isnt warming up because its being cooled. and the only thing the thermostat does is warm the car on start up. and its not doing this. so im going to get a 3rd thermostat and im getting this one from autozone instead of advance. will update

 

The thermostat does not serve to heat the engine at cold startup. The following is a description of the cooling system in your Saturn.

The Saturn cooling system has two unique features, a coolant recovery reservoir and an inlet side thermostat. The system is filled through the pressure cap and doesn't require any bleeding. Flow from the tank fills the engine cylinder block, radiator, heater core, and hoses.
During engine operation with the thermostat closed, coolant is pumped through the cylinder block, cylinder head, heater core inlet hose, heater core, heater outlet hose and back to the thermostat housing. Coolant flows past the thermostat element and back to the water pump inlet. Some coolant is routed back through the engine block to the thermostat cavity.

When the thermostat begins to open, coolant flow is then routed from the pump through the cylinder block, head, heater inlet, heater core, heater outlet and back to the cylinder block. Coolant is also routed through the upper radiator hose, radiator core, lower or outlet radiator hose past the thermostat to the water pump. Coolant flow from the heater return and lower radiator hose wash the thermostat element, thus regulating coolant flow through the lower radiator hose and to the water pump.

(Edited to remove coolant bypass valve which first and second generation S car engines do not have to my knowledge

 

3rd gen d cars do have the bypass.

Amend the last post to read

The Saturn cooling system has two unique features, a coolant recovery reservoir and an inlet side thermostat. The system is filled through the pressure cap and doesn't require any bleeding. Flow from the tank fills the engine cylinder block, radiator, heater core, and hoses.
During engine operation with the thermostat closed, coolant is pumped through the cylinder block, cylinder head, heater core inlet hose, heater core, heater outlet hose and back to the thermostat housing. Coolant flows past the thermostat element and back to the water pump inlet.

Some coolant is routed back through the engine block to the thermostat cavity. A thermostat by-pass valve controls return coolant flow through the cylinder block and dampens sudden coolant pressure surges by venting coolant back to the water pump suction side.

When the thermostat begins to open the by-pass valve begins to close the cylinder block passage. Coolant flow is then routed from the pump through the cylinder block, head, heater inlet, heater core, heater outlet and back to the cylinder block.
Coolant is also routed through the upper radiator hose, radiator core, lower or outlet radiator hose past the thermostat to the water pump.