Here is a little foreword on what I have replaced on my car lately to help diagnose my problem. About 2 months ago I replaced the Air Intake Sensor and about 1 month ago I replaced the Throttle Position Sensor. All of these were alerted by the Check Engine Light. I have also cleaned my air filter and throttle body.

Lately I've been at idle, even right from start up (in Park, A/T) and the RPMs are very low and the car is definitely bucking like it wants to stall out. If I am at a red light it does the same thing and if I put it in Neutral it seems to get better, but does even shutter a bit too at times.

Also, when I am driving on the highway it may do this sputter when I give a bit more gas and it down shifts to accelerate.

No CEL yet, but curious if anyone else knows what it might be. Any insight is appreciated.

Thanks.

-Steve

 

have you checked your maf? if it's dirty clean it. also test the voltage per fsm.

 

Sounds like my car did before I replaced the Mass Airflow Sensor last year. I also cleaned the Throttle Body and changed the Engine Coolant Temperature Sensor, and around the same time, put in a new gas cap.

Probably a combination of the above fixed my problem, but the MAF was far and away the biggest improvement. My car has not stalled at all since replacing it.

I bought mine off e-bay for $135 or so, new. It's a knockoff but I think it works just the same.

 

Clean TB and MAF?

Check coils and plugs. Clean grounds on top of engine. Change PCV. Check IACV per FSM. Throw some chevron techron in that bish too.

 

+1. I would go for the coilpacks being the problem here. They are probably failing under load and not throwing a code. Start looking for the defective one.

 

also try to check for a vacuum leak on the upper intake plenum gasket....got a little hesitation problem at idle for 1 year...without any component problem....but the leak was bigger and later the pcm throught a misfire code....you can check it with iontake cleaner....just spray on the gasket and if it comes dry in second...theres a leak...

 

Thanks everyone for the quick responses. TB and MAFS have already been cleaned. I was thinking it could be a faulty MAFS, but no code yet. Would it throw a code if it is dead?

The mechanic recently took apart my CAI to replace the TPS (needed to re-tap holes, that's why I couldn't replace it), so I will check all connections and clamps.

thegontran- where / what is the upper intake plenum gasket? Does spraying the intake cleaner on a faulty gasket cause the cleaner to suck into the leak, to show that there is a leak?

Thanks again guys.

-Steve

 

Oh yeah... I'm also getting awful MPG's if this info helps too.

 

A Vacuum leak can screw up MPG (introduction of unmetered air). Does the idle fluctuate?

What holes did the mechanic have to retap? The TPS holes?

 

Yes, the idle fluctuates quite a bit. Normally it is around 700- 900 RPMs when it was running strong. But, now I'm lucky if I get 600 and it bounces around at 400 RPM's when it really feels like it's going to die. It never has stalled out though.

The holes he re-tapped where the ones that go directly into the throttle body that accepts the bolts for the TPS.

 

It sounds like you have a vacuum leak (probably where the TB mates to the UIM if that was removed) - hopefully the mechanic recalibrated the TPS (and it's not moving from engine vibration) - but the MPG decline and idle fluctuation definately point towards a vacuum leak.

 

I was thinking the same thing, is it adjsuted correctly?

 

Yeah I was thinking the same thing as far as whether or not it was recallibrated properly. It had been running fine for about a month or so, but really I guess that doesn't mean too much.

I'll probably end up bringing it back to have him take another look. Of course I will make sure it is at no charge.

Thanks guys.

-Steve

 

I think you did this already, but i had a similiar problem in my '96, and one of the vacuum tubes got blocked, when I hired a mechanic to clean my intake manifold. It could also be bad IACV, if its low RPMs at idle, and you had to completely open the idle adjustment screw to get it to be 700 or 800rpm.

 

omg! good luck ive had the same thing for like 3 months now and its ben in and out of meks and askin questions all over here but...nothing yet i cleaned all my sensor and i dont have any leaks fule presure is good and oil sensor,and oil pressure,and compresion are all good now i have to get a ,multimeter and check my coil paks,MAF,TPS and check my injectors ...thats all thats left ive checkt and re-checkt evry thing else

so good luck and ill be shure to let u know what i find im gona finaly get the meter this week on my days off

 

I had the same thing as you man. My idle would jump from 400 to 600 while im at park and when i put it on neutral it would go up to 700 to 800. When they did a 01 swap in my max the wiring harness got messed up. What I would do is while the car is on and in "D" and put the ebrake up. NOw go under the hood and start messing with the wiring harness. Move it around a bit and see where you would mess with the harness if the idle changes back to normal. There can be a shortage in the wiring harness like I had. MOve the harness and check. This worked for me. When I found the shortage I tightened the harness up and it worked. After that i put the idle back to normal and all done. NO more sputtering. NOw i dont have to press the gas further down then i have to, to be able to go. I use to press the gas pedal to a certain point to make it go and not sputter. Thats where the gas issue come up. Sorry for the long writting but check that out.

 

bori thats what i did for my stalling a wile back..my max just staled randomly sometimes....turned the engine on and got under the hood moved some wires and it ended up being the wires nex to the brake booster moved them and it shut the engine off....so i quick tide them to the brake line thats close to them so they dont move and "wala" no more stalling...did this for my sputering prob.(wich i alredy said is the exact same as his) and nothing has changed but no 1 is the same so yeah give it a wirl see what you get....this method workt perfectly for my last prob so it is recomended u give it a try.....

 

See there you go. It wont be the same for everyone cuz mine was by the top left corner of the manifold where the wires bend. Check it out i hope it works for you.

 

So which wiring harness are you talking about? Are you suggesting I check all harnesses?

Unfortunately, I think it might me more than this because my engine is sputtering even on the highway when I remove my foot from the gas, then coast and then begin to accelerate again. Were you experiencing this problem (sputtering while driving) too?

-Steve

 

Yes I did. I use to try to just cruise in the street about 45 to 50mph and it would sputter and thats with the foot on and off the gas pedal. Then in the highway I would try to cruise from 65 to 70mph and it would do the same thing sputter whether the foot is on or off the gas pedal. Check it out. Just play with all the wiring harness and move it around before you go and buy stuff to try to fix it. It helped me out. I was thinking of replacing coil packs and etc. to fix it. Just do it if you wanna try out.

 

Looks like I'll have to give this a try because I have the exact symptoms you had.

Any specific harness I should try first? Stay around the IACV, TPS, MAF area? or just give 'em all a shot?

Thanks for your insight!

 

Just try everything. You can really say where to start there is no procedure you just gotta find the shortage. Now when you are moving the harness make sure you laten to you idle cuz most likely where it changed thats where itmight be at.

 

just a thought, my car has been idling at a sputter. rpms seem fine and i just replaced my coilpacks a few months ago along with an oil change. i have high mileage but my car rides and drives perfectly without a sputter, its only at lights or when it has a chance to idle. i have an exhaust so its very plain to hear, just kinda slight sputtering sounds. any help would be great! i also cleaned the throttle body and maf a few months back, when turned out it was my temperature sensor. so i dont think its anything that deals with those problems.