2003 GM Ecotec Engine Issue

My daughters college beater is a 2003 Olds Alero with the 2.2 Ecotec 4 cylinder. She has been driving this car for 4 years and it has been a decent car. She is 150 miles from home and calls me with each and every issue. Two months ago she calls and tells me that when she stopped at a stop sign it started to run rough and the rpm jumped around a little. When she pulled away from the stop sign it was okay. Only happened the one time. Today I get a call that it did the same thing. Both times no check engine light so no code to scan. So I am trying to figure out what to do. Trying to trouble shoot an intermittent car problem remotely by talking to my non mechanical daughter is impossible. The no check engine light also has me puzzled. Would a bad fuel pump throw an engine error code? I really have three options. Do nothing and hope it never gets worse. Throw parts at it. Take it to a repair shop and have them throw parts at it 4 times the cost of doing it myself. What are your top thoughts on the problem? Even if I throw parts at it I won't know if I actually accomplished anything. The intermittent frequency with months between will make trouble shooting just about impossible. The car being 150 miles from my workshop also adds to the challenge. Thanks for the help.

If you're not getting a check engine light it's still reading all the sensors as being in established parameters. I'd be wondering if you've got a fuel pump or fuel filter issue or a vacuum leak popping up, don't think it would be a spark plug because that would throw a code, least it does on my Ford. Might try a can pf Seafoam in it in case it's a dirty or fouled injector.

I agree with wisbaker, Sea-foam or Gumout.

lot of problems with coils and coil covers.Also EGR sticking . Hard to tell for sure so far away and intermitants

I had two in collage at the same time AAA was a good investment and I own a tow truck... It was worth it to me not to have to take 3/4 hr. of my time to have them drop it off at my shop...

1) Trying to trouble shoot an intermittent car problem.

It difficult remote are not.

2) Would a bad fuel pump throw an engine error code

More than likely not

3) you can trow parts at it till you run out of money then have to pay someone to fix it.

Lucky for me I don't work on many of those engines are cars of that platform I do not see anything in the post I could give you any tips on

A battle plan needs to be drawn up so you can answer the questions I would start here.

https://www.google.com/webhp?source...amp;ie=UTF-8#q=2003+Olds+Alero+2.2+rough+idle

Im thinking EGR ,,sticking open , car comes to stop ,idle , unmetered air from egr causes rough idle, go to accelerate, increased rpm can handle egr flow. This will not always set a code . An ignition failure would be more noticeable under acceleration. Fuel pump would be hard start cold, sluggish on long uphill or hard accel .

Those engine don't use EGR.

well that shoots my outstanding description of a fix , lol

I have a few suggestions....
My first suspect would be spark plugs. Any idea how old or what condition they are in? There is a good possibility that one or more could have become momentarily fouled and caused rough running. That will not necessarily set a code. Misfires are generally only monitored at idle.
Another thought would be the variable valve timing mechanism could have stuck in the "high RPM" position as the car came to a stop and an idle. This may or may not set a code. Depends on the circuitry used to monitor it.
I would be inclined to say NO to sticking EGR. EGR has some VERY sensitive monitoring systems. Most systems are using a DPFE sensor, and that will set a code for the slightest out of range flow.
Valve guides, valve seals, and the valve train in general come to mind. A bit of stray oil coming down a valve stem can cause some momentary roughness. Also, this will generally NOT generate a trouble code, and will usually not light up the Check Engine light.
A dirty contact at one of the coils can also cause trouble without setting a code.

Some things to consider:
Modern engines use varying levels of emission control along with varying levels of monitoring. Even though a bad plug will set a code on some guy's Ford does not mean that it will on your Olds.
Generally, when an EGR system generates a symptom or a code, it will be plugged up to the point of causing constant or frequent roughness along with a check engine light and a trouble code. Same generally goes for plugged injectors, weak fuel pump, or unmetered air leaks. The fuel system is closed and monitored, and maintained at a specific pressure. Variation from that will light the light. Plugged injectors will not unplug themselves, thus not causing an intermittent problem.
As to the SeaFoam, it won't hurt anything, but don't expect it to help much. The "mechanic in a can" will generally not fix faulty parts.
Given the infrequent and intermittent nature of the problem, I suggest that it will have to get worse before it will get better. Very difficult to verify the problem, even more difficult to verify the repair.

I have the same motor in a little older car(2002). It will do that if the spark plugs are bad. They are simple to change as they are under the coil pack. There are no plug wires. Pretty simple system. Some time it will throw a code and some times not.

You could also have a fuel issue. Some thing like water in the tank sloshing forward when she stops. The reason I really think a fuel issue is more of a long shot is with all the ethanol in the fuel, any water usually gets burnt in the fuel injected motors.

First thing I'd do is look for a soft mushy vac. hose around the throttle body, seems like I've seen that before, then I'd clean the throttle body and plate. hold throttle open, spray tbi cleaner or carb cleaner and scrub the inside with something like a tooth brush. If the idle speed motor comes out easy(probably 2 screws) I'd clean the end of that and the seat in the throttle body.

Fuel filter

Thanks for the ideas. I put new spark plugs in it 4 years ago when we first got the car. They have about 25,000 miles on them. The car has about 150,000 miles. I think I am going to trade cars with her for a few weeks and drive the crap out of the thing and see if I can figure it out.

is she keeping plenty of gas in the tank? I remember hearing a guy say that his kid would just keep enough gas in the tank to not run out. the car got to running rough.

I have a 99 silverado with 6.0 engine that did that three times this winter.each time it was below 0 degrees temps and it did throw a code once. Repair shop checked it and it showed either a mass air sensor or a oxygen sensor at fault but we both suspected that it was caused by icing in the air intake due to the cold temps at the time.

My guess would be in the coil pack, its a "cassette" style on that one.

Duane,

Sounds to me like a chunk of carbon is getting stuck in the egr. You could temporarily create a tin block off plate and install it beneath the egr valve. This would assist in troubleshooting and not throw a check engine light.

D.