97 SC2 bucking

It's not quite as bad as the title makes it sound. It doesn't happen
from a dead stop. Instead it usually just happens while I'm driving on
city streets, and it occurrs just when I back off the accelerator just
a little bit. I can feel the car slowing just a little bit, but then
catches up again. This all happens over the course of 1-2 seconds. It
doesn't happen consistently, and happens almost every day.

It's also coupled with a loss of fuel economy. I used to get around 32
MPG, but now it's around 27-28 MPG. Anyone got any Ideas?

Could this be a failing fuel pump?


Thanks.


Remove the BALONEY from my email address.

 

Coolant Temperature Sensor?

 

Sounds exactly like my problem...I have a 99 sl1. Started about 2
months ago, has gotten progressively worse...replaced spark plugs and
air filter, didn't change the wires...almost feels as if its
misfiring. today, it was doing it upon acceleration, but it only did
while on my lunch break. the rest of the evening, it was fine?

any ideas? coolant temp. sensor? I hear stuff about those on this
car...would that really cause hesitation/bucking/irritation?

 

Lane's canned response #23:

Before you replace anything, stop by any Autozone store and they will read
the stored diagnostic codes for no charge. It beats guessing and replacing
parts that may not need to be.

Lane [ lane (at) evilplastic.com ]

 

Diagnostic codes? I never heard about this.....where is that stored?

 

All cars since about 95 have a computer module that controls the engine and records standard diagnostic faults. You can buy a reader for about $50 and up or as suggested take it to Autozone and they'll read them for free. Or take it to a mechanic or dealer and pay $50 to $100.

Codes will tell you what the computer sees as a problem. Not always clear what to fix but it's a start.

David Ross

 

I can tell all of you, from experience, what you're describing sounds
like a *plugged up* EGR vlavle. DO NOT let some mechanic try to charge
you $400+ for a new one. 9 out of 10 times the airway gets plugged up
with carbon (especially nowdays with Bush's alcohol-based gas) and it
doesn't do it's job. You DON'T always get a DTC (Diagnostic Trouble
Code) on the S series when this occurs.

 

If it is the egr you must clean all the carbon out of the passages in
he manifold once you remove the egr. Cleaning an egr is pretty much
worthless once you start to have problems.. for $89 you can buy a new
one at advance auto but the poblem will come back if you have a lot of
carbon. My suggestion would be to get upper cyclnder cleanre from GM,
run that through, change the oil and filter after that (must do after
the decarbonizer) THE replace with a new egr.