Engine Sputtering - '96 GA

[Brad97GS]

A friend of mine has a '96 GA with the 2.4L and a 5-speed. Lately she has noticed a sputtering problem, and I thought you guys would be the ones to ask. :) Here are her exact words:


Now all I have to do is figure out why my car sometimes putters to a halt when I first start it up and drive a little ways....

[then, after I inquired a bit more about it...]

Yeah, Brad, it sputters like it's not getting enough gas or oil or something to that effect and sometimes it even turns itself completely off (the engine, not the electrical stuff). It usually happens when it's being used for the first time in a while...sometimes after it was driven somewhere, stopped, and then driven somewhere else again. I thought maybe it was something to do with the oil/engine, but then I thought maybe it was the fuel injector.

It's hard for me to get an exact idea of the problem without experiencing it, but something that pops into my head immediately is that there is a problem when the car switches over to closed loop. Of course, if that were the case, wouldn't it run bad the whole time while in closed loop? Could a gummed up IAC valve cause this sort of problem? Perhaps this is even a common thing with the 2.4L engine...that would be nice, as that means there is probably a common fix. :) Thanks for any help!

[4kQuad]

Always start with air/fuel filters, at least that would be my fisrt step. it sounds like she has good spark. IACV could be it, but I would think the problem would be there even after heated up.

So it's back to air/fuel mixture getting messed up. Does the 2.4 have a MAF or a MAP like the 2.3. Dirty MAF's can cause problems like she is having. Of course listen/test for the vac leaks.

Then take 2 asprins and tell her to call the mechanic in the morning.:lol:

[Brad97GS]

The 2.4L has a MAP sensor, no MAF. I didn't think about the air/fuel filters. Also, I didn't think about vacuum leaks, which is crazy because I just fixed a couple of those on my Riv...

Not sure if I'll get a chance to actually look at the car, but I'll feed the info to her. She can take the aspirin!

[Matt95GT]

Yea... check the basics first... fuel filter, spark plugs/boots, vac leaks.

Originally posted by Brad97GS
... something that pops into my head immediately is that there is a problem when the car switches over to closed loop. Of course, if that were the case, wouldn't it run bad the whole time while in closed loop? Could a gummed up IAC valve cause this sort of problem?

Yes... on a warm restart that's exactly what I was thinking... which makes me suspect the O2 sensor.

Reason being... I've 'artificially' induced this issue on my car due to some of the mods. My wideband O2 controller's simulated narrowband output feeds the O2 input to the PCM. Unlike the original unheated O2 sensor, the wideband setup is heated, and also does a self test/auto-calibration on each startup... which takes about 45 seconds. During that time, the controller outputs exact stoich (14.7:1 A/F). Problem is, if the car is already warm it'll go into closed loop almost immediately. Idle usually runs too lean, but the PCM thinks it's running perfectly stoich... and will start sputtering badly. If I touch the gas pedal, it will stall during that period. (My simple solution is let it run for a minute before driving)

Whoa... that was kinda long... but the point I'm getting at - misreadings from a worn O2 sensor can cause this issue. Although a dirty IAC or vac leak could cause similar issues, they shouldn't ever occur specifically when it goes into closed loop.

[Brad97GS]

I should see if she can do what you do - let the car run for a minute before taking off. If the problem goes away, we can pretty well bet that the O2 sensor is the problem.

[Matt95GT]

Originally posted by Brad97GS
I should see if she can do what you do - let the car run for a minute before taking off. If the problem goes away, we can pretty well bet that the O2 sensor is the problem.

May help slightly (as O2 warms up via exhaust gas) but remember that my O2 rig is way different. She isn't going to have a "warmup/auto-calibrate" proceedure to wait out... so it may still occur if the worn O2 sensor never snaps out of its bad mood.