Saturn SL1 stuttering

saturn

#1

I have a '96 Saturn SL1 that has a behavior I’d like to get someone’s opinion on. While accelerating, it normally doesn’t have any problems. However, when I let off of the gas, the car stutters and jerks like it’s not getting enough fuel. When it idles, the RPM slows enough to make the car cut out unless I rev it up. Any help with this would be most appreciated!


#2

[b]The problem might be with the Idle Air Control motor.

The IAC motor controls the engine speed anytime you let off the accelerator. This means if you are driving down the freeway, or at a stop. The IAC motor controls the engine speed.

So from how you describe the problem, the IAC motor would be the first suspect.

Tester[/b]


#3

Thanks for the response! Is the Idle Air Control motor something that’s relatively easy to change out by a car novice? I’m willing to give it a go if it’s relatively painless. Thanks again!

Brent


#4

It is on this model, first remove the air cleaner from the throttle body. Then remove the two connectors to the throttle body and the two vacuum hoses. The vacuum hoses are connected to a single block so just remove the block. The remove the two screws holding the throttle body to the manifold, gently pull the throttle body from the manifold and disconnect the throttle linkage. Then remove the IAC from the throttle body.

I know this sounds like a lot, but its easier to do than to write down. While you have the throttle body out, you may find that the backside is caked in carbon, Use a fuel injector/throttle body spray to clean it up. The passages to the IAC maybe clogged up too and that may be the real problem. You can clean the EGR valve while your at it and that may help too. Heck, use the whole can.

If the gasket doesn’t tear, you can reuse it also. Tester won’t agree with that but I’ve reused mine about a half dozen times already, but I think I’ll rep[ace it next time. BTW, these have a bad history with the intake manifold gasket around the #1 cylinder. It usually results in a high idle though, but if it gets bad enough, it could cause your problems. Spray some of that throttle body cleaner around the gasket at the #1 cylinder and see if it affects the idle. If it does, this is a harder job. You may want the dealer or a good independent mechanic to replace the gasket for you, about a $200 job.


#5

I’ll try it out here in a day or 2 and let you know how it goes! Thanks!


#6

I took the throttle body out and cleaned it out. I also cleaned out the IAC. Ater reinstalling everything the way it was, when I start the car, it revs up way high immediately without me touching the accelerator. Any idea what I messed up? Did I mess up the IAC somehow? The throttle linkage is connected as it originally was the best that I can tell.

Thanks in advance for any help someone can give.

Brent


#7

I solved that problem by disconnecting the battery for 30 seconds. My problem with the car stuttering remains. I will replace the IAC next.


#8

Did you check the intake manifold gasket yet?


#9

Keith, I’ve been out of town the last few days. Sorry about that. I tried the trick with the intake manifold gasket but there was no change with the idle when I sprayed it with the carb cleaner. I changed out the IAC and I still have the same problem. Any other ideas before I take it to tha shop? Thanks a lot for you thoughts and ideas! I really appreciate them!

Brent


#10

The problem turned out to be my EGR valve. I’ve suspected this for a while but didn’t want to waste money on a part I didn’t really need if that wasn’t the problem. I took it to a shop to diagnose and they initially found a bad throttle sensor. This in itself didn’t solve the problem. Their testing also found the EGR valve to be bad. That solved the problem!


#11

Nice to hear how it turned out. I’d been having problems with the sticky throttle body, kept having to clean it about every 5k. It looks like my EGR was the cause of that too.


#12

I’m having a very similar problem with an 02 SL1 with 63k. I changed the air fliter, pcv valve, front O2 sensor, plugs, wires and it still dogs on acceleration and doesn’t idle smooth. The check engine light is NOT on, but 28 mpg is terrible for that thing. Perhaps I’ll take off the EGR and clean it… or replace it?


#13

Was the EGR the problem with the '02 running poorly? I have an '02 with the same symptoms.


#14

My '96 SL2 is having the same problem and they replaced the idle control valve once to no avail. I’ll have them check out the EGR valve when I take it in tomorrow. Billions of thanks for this thread! I’ll report the results.

John


#15

So here’s the long answer. Luckily I didn’t have to spend a ton of money to get it.

We replaced a faulty MAP sensor, which had been clogged with soot and carbon. Do I hear some of you wondering how carbon deposits got to the top half of the engine? Via the EGR! But that’ didn’t stop the intermittent stuttering problem.

The problem is the EGR valve…sort of. The valve works fine, but my engine is worn to the point that it’s producing a lot of carbon deposits. The stuttering problem occurs when the carbon deposits are passing through the EGR while it’s open (during acceleration). So far, I’ve been able to clear the open valve by gunning the engine.

My work-around has been to limit my RPMs to ~3200 MAX. If I exceed 3500-4000, I typically have a stutter. Revving the engine past 4000 RPMs (briefly) will typically clear it.

Does anyone has suggestions for limiting carbon in an older engine? (Short of a ring job that costs more than the car is worth.) I took my mechanic’s advice and put premium in it for the past month or so (can you say ouch?) but no real change. He also recommended 10W40 and an oil thickener by STP, which I need to try again.

Thanks again for this thread - it was a great help!


#16

culteredperl,
Please state your CURRENT symptoms. They sound somewhat different than when you started your post.

Other people are claiming that the same thing applies to their vehicle; but, the symptoms are DIFFERENT. This is similar to mixing oranges and tangerines. They are different fruit!