almost stalling, but not?

okay so ive had this problem for a while, but i have a little more info this time. Almost every time I'm out driving in my car, (it happens atleast once) the engine seems to drop in rpms, almost like it shut off, but then it started back up to normal. Sometimes when you put it into reverse, it happens, and then you give it gas to back up, it wants to stall. And then other times it happens when your just sitting at a stop sign. Today i was coming home in the dark, and it did it as I was pulling into my driveway. I noticed that as it happened, my headlights went very dim, almost as if they were completely turned off, and then turned back on again as everything went back to normal. ... whats going on?

did u check ur battery.?

battery is brand new. i even replaced it a few months ago, and i had the problem before i replaced it too.

Were there any codes? If it seems throttle related, check the TPS. If idle related, clean the throttle-body and check the iac. When was the last time you replaced the fuel filter? Is the fuel pressure ok?

Sometimes, performance mods can cause problems.
Does this have an automatic tranny?

No there werent any codes unfortunately. I checked the TPS a few months ago with my meter and it seemed like it was working alright. How would I go about cleaning the throttle body? And I was thinking bout replacing the IAC, but wasnt sure what the cost would be. I already replaced the o2 sensor. And I replaced the fuel filter in the summertime, and the fuel pressure should be okay.

And its an automotatic transmission. thx for all the help sofar

what is the idle rpms?

i have no idea. i dont have a tach. it seems pretty normal tho.
one time this happened, and the rpms jumped up high and stayed for a 30 minute trip in the city. It was hard on the transmission because it couldn't downshift properly while it was idling high.

also. last night when it happened, it happened just after i turned the steering wheel all the way to the right. The engine struggled for a second because i had it turned so far. Once i straightened out, thats when it acted goofy.

okay so i got a lil more info. today it happened again. except this time it completely stalled. I was in a parking lot, and was leaving. when you leave the parking lot there is a steep ramp that you drive down. I was going down it and stopped, and then the car struggled for a few seconds and then stalled. I remember it happened a few months ago in the same spot. This is making me think its a fuel related problem. ?

it happened AGAIN grr. in the middle of the pay station in a busy parking garage. it stalled. over and over. i had to give it gas to keep it going. I went and bought throttle body cleaner. I took out the iac valve (which was all black and gungy) and cleaned it really good. along with the throttle body. Hopefully this helps

okay so nothing i did sofar has fixed the problem. I'm beginning to think that one of the cylinders is misfiring or something. A few weeks ago i replaced my plug wires and it didnt make a difference. My spark plugs are only a couple months old. Plug 1 and 4 were extremely hard to remove, while 2 and 3 were easy. Don't kno if that says anything or what. And they looked pretty clean when i removed them. any thoughts?

My 98 Cav is having a similar issue... tonight it finally threw a code - P0404 -
EGR valve pintle sticking open.

Might want to check your EGR valve... I'm looking to see if there is a way to
clean mine.

Good Luck!
Scott

thanks for the info. I was somewhat thinking of the egr valve, but wasnt quite sure. I already replaced the iac and tps, and it hadnt made a difference. There isnt really much to replace on these cars, so its kinda confusing as to what the problem is. As for cleaning it, i think throttle body cleaner can be used, but i'm not 100% sure. I'll probably take mine apart on the weekend, get a new gasket for it, and clean it good. Hopefully it will cure the problem.

Alright. So my father and I went to the scrap yard yesterday and got ANOTHer iac valve, tps, a map sensor, and an egr valve, and threw it all in there. The car drove fine for a few minutes, but when i pulled off the highway into a parking lot, it started idling very low and i had to keep giving it gas for it to stay going. And also, when you brake to slow down, as you get slower, the engine begins to shake, and the whole car shakes. We put the origional map sensor on because we noticed the numbers were different. Took it for another drive, same thing. I pulled into my driveway which is slightly slanted upwards, and put it into park. When i did, the rpms dropped, came back up, and then it just kept surging high and low. We popped the hood looking for any vacuum leak, but couldnt find anything. No matter what we do, we still have this problem. I am somewhat thinking its a clogged injector? Would it have the same affect?

have you checked your catalytic converter to see if it`s pulgged ?

=) i dont have one. just a muffler

Sounds kinda like it might be the IAC valve to me. It actually sounds like you're having an issue with a vacume leak. Which can be caused by the IAC. Actually it can make it throw a MAP sensor code too.

I had idle issues at one time with my `91 sunbird ,3.1 MPFI . put in a new iac ,took it for a rip ,only idle issue then was about 3500 rpm sitting still .........LOL .Had to leave it in drive ,stand on the brakes to shut the bitch down. put the old one back in just left it .I was told at dealership tho that if you put in a new iac u have to take it for a run to "re-train " new iac . never did worry about it but I know it was a PITA when it wanted to do the stall thing . Have read on some posts where guys will use carb cleaner to spray CAREFULLY around engine looking for vacuum leaks. when the motor starts to rev you`ve found the problem area.

And like jdl says I think I would look at your mods whatever they may be

i took all my mods off tho a while back. everything is stock. And i've tried 3 different IAC's and they all do the same thing. So i figure that cannot be it. lol. And if it were a vacuum leak, wouldnt it do it all the time? It only does it once its warmed up, and not all the time. I went out yesterday and bought some dura lube advanced fuel system treatment stuff. Next time i fill up, i'll throw it in and let you know how it goes.

Also. I was reading somewhere on the net that having an airbubble in the coolant system can do this? Engine revs up because it thinks its cold (no coolant hitting the sensor or something) and then water pump kicks in, shoots coolant through the lines, hits the sensor, senses its hot, then idles down. and it goes in an endless loop. Is this true? Because if it is, that May be part of my problem. 2 weeks ago I noticed my heat was slowly getting worse, almost to the point where i had none at all. I checked my coolant level, and there was nothing in the bottle. I lifted the cap off, shined a flash light down the hole, and there was a little bit of fuild left, about 3/4 of the way down. I then filled it up and noticed that i had a leak, but it wasnt a major one. I don't know how long I was running with low coolant like that, bit I had been driving around alot. Could i have air in it somewhere?

water pump is going all the time . did you check you egr ? you said plugs looked good so it must not be overfueling . I think I`d get pressure checked .do you have a Haynes manual ?

im not sure how to check the egr. but i did replace it with another one. no difference. And i dont have a haynes manual, but i do have an online version that i reffer to.

Sounds like the EGR is sticking open or the IAC valve is on it's way out. That's where I'd start.

I think I`d just put all the old stuff back on and have your Dad take it to a dealer and let them look at it ,give them an hour. costs a few bucks but at least they can steer you in the right direction.have them check fuel pressure and for codes , putting old used parts on could be aggravating things or causing other probs. and there is no sense in throwing a bunch of new parts into it yet. check your egr valve ,reach under it ,you should be able to move diaphragh up and down with not alot of effort. give it the spray treatment around throttle body etc ,see if it gets horny then.

Also.... why get sensors at the JY? Sensors arent really expensive, just buy new ones.

Also, reset the computer when you put new sensors on.

yes, sensors can be expensive when your a student living on your own and have very little money to spare. example: new egr valve 93$ canadian. scrap yard=free. :p just have to take a few to find one that works. I'd rather pay nothing and go through some trial and error, than to throw out a bunch of bucks to start replacing things that may not even need replacing. Anyways. I'll try putting the origional iac valve back on tomorrow, and see if it helps with the idling.

Have any codes been set by the computer with this problem?

If so, are you resetting the computer after you swap out these parts?

Have you ran a compression check on the engine?

Could be a bad fuel filter... does it do it after the engine has come up to
operating temp? That may mean that the coil may be breaking down under
load... have you checked the battery cables for voltage/current loss? Have
you tried a different battery? The battery may have a bad cell in it... have
you tried a fuel pressure regulator? Have you throughly checked every
vacuum line?

Have you bought a service manual for the year of your car?

There's so many things that it could be, a little diagnosis goes a long ways! :smile:

Scott

no codes were sent to the computer. And yes, it only happens once it reaches operating temperature. the idle seems to be a little rough lately since i have been replacing parts.
No there is no vacuum leaks, i have searched countless times.
I have a brand new battery, havent had a single problem with it. Voltages seem to be okay.
I havent replaced the fuel pressure regulator, but when the idle was surging up and down, i unplugged the vacuum line on it and it did not make a difference. same with the egr valve.
I replaced the fuel filter in the summertime which isnt that long ago. Should I replace it again? I do know that when at a slant, the car tends to want to stall (sometimes).
and whats this coil breaking down under load that you are talking of?
thanks for more of the help. Tomorrow i will be going out to take another look, and possibly buying a new iac valve.
ooh. and yes, everytime i had installed a new part, i pulled the ecm fuse and reset it.

if the iac is malfunctioning ,a trouble code indicating this condition would most likely sent ,stored in ecm.........to check iac valve ,unplug the elect connector and ,using ohm meter,measure resistance across terminalsA and B,then terminals C and D .each resistance check should indicate 20 ohms or greater if not replace it . next ,remove the valve and clean valve and housing which you did already .apply battery voltage to IAC valve terminals ( one at a time ) while holding the valve against a good ground. Make sure the valve pintle extends and retracts with voltage signal.If thre is no movement from valve replace it with a new one

The IAC valve pintle should not be longer than 1-1/8 inch ,measuring from tip to housing. if it`s longer push pintle into valve with side to side motion. also replace O ring.

this info comes from Mr Haynes ,hope it helps

i'll take a look at the iac valve later. i went out to canadian tire to check the price of a new one, 129$ canadian :| umm i dont think so. I bought a new air filter because the one that was in there looked pretty dirty. I also took throttle body cleaner and sprayed a bunch in there again. I also threw in some fuel system cleaner. I was taking a look at the vacuum lines again, and i noticed that the one that comes off the egr valve goes to a little squareish thing that is attached to the throttle body. and there is a wire connector coming off that. I was wondering if that piece may be malfunctioning?

FUNNY STORY which could help in diagnosing this problem

So i figured my car was good to drive around, since making short trips i didnt have a stalling problem. My parents and i decided to drive out to my grandmothers which is about a 15 minute drive down the highway. We made it there alright, but as i parked in the driveway, the idle started surging. I just shut the car off and forgot about it. 2 hours later, we decide to go home. Get in the car, turn it on, idle jumps WAY up, then low, then WAY up, then low. you can also hear something making a weird nose in under the hood. My dad says to put it in reverse. as i did that, it stalled. I started it back up, and the idle was still going crazy. I popped the hood, and got out of the car. as i did, the surging stopped. I lifted the hood and everything looked okay. Dropped the hood, went back into the car. Sat back down in the seat, put my seatbelt on, and the surging happened again. Once again, i popped the hood, got out, opened it, and the car idled beautifully. ?! It made no sense to me. I sat back in the drivers seat, and again, it started. my dad said "its something in the seat. theres a wire underneath getting pinched or something" i didnt believe it. So i got out of the seat, and sure enough the surging stopped. Looked under the seat, and the only wire was for the seatbelt light. unhooked it, no difference. But then i stood on the side of the car, instead of sitting, and then it started to surge. Which means its only happening when the car is tilted or slanted at the right angle.
whats going on??? what can be causing this???

Fuel line getting pinched of somewhere.pump is building pressure and forcing fuel thru in spurts ??????.follow the line from tank to engine. My `91 had the fuel lines running up drivers side and crossed over rear axle near drivers side back wheel. rubber lines at front coming up to engine on my 3.1

ksadfl;asdjk

i had a suggestion that it may be water in the tank. could it cause this problem? and for this long?

Wow mine does the same thing.
Mine overheats aswell.
Lol.
Wow whats with these cars..

okay so i've tried about everything, and nothing has helped. I am thinking i have 2 seperate problems i am dealing with.
The main one is: Car randomly dies (loss of power to coil packs maybe?) when idle, or driving slowly. It doesnt sputter, it just dies. But, only for a second, and then starts back up itself. It does this many times. I was leaving work one day, the car did it while it was cold. And it seems to be mainly doing it when i am turning the steering wheel, but not always... help? this is an impossible fix ><

Dont know if this is relavent but I had an 89 beretta and near the end it would want to stall out the rpm would shoot up and go down, some times it would stall out and in the worst place an intersection ect, well we couldnt figure it out and I had a friend that is a mechanic they had a truck in for the same issues and said it either wasnt getting enough gas or getting to much, we never did figure out exactly what it was but I feel your pain, its annoying and embarrising.

Wow yeah its like mine loses all the power when it turns then it will die.
=S
Wtf is wrong with our cars.

i have a 98 caviler it runs great but after driving it for awhile it seems to get a small glitch changed wires plugs coal packs cam,crank,map sensors not sure what else to try

have you checked for vaccuum leaks in you intake hose. it make cause your car to stall when in drive and reverse but it will seem to run fine in neutral and park.

hey! I've been having that almost exact problem in my 98 cavy 2.4 ltr. When i bought the car i even got the tranny rebuilt under the warrenty b/c i didn't trust the one that was in due to the high miles. however now, even after the tranny fix i still have the problem. I live on a street that inclines down so if i let the car warm up, and then just let it ride to the bottom of the road it idles rough. Sometimes the rpms bog down from 600-700 rpms to 2-3-4 rpms. and as you say, the headlights dim and its about to stall but if i tap the gas it usually kicks out but on occasion ill have the adverse affect and it will keep revving itself over 1200 rpms even when i hold the brake down. and i tell you i am at a complete loss for what is wrong.:banghead: but in addition to my problem my car also misfires when i try to accelerate as if its not getting enough fuel. its worse accelerating when the car is at a low rpm than a high one b/c it bucks more when im not going fast. ive had the fuel injectors clean, the mechanic said my fuel pressure is good the only thing i can think of is a few fuel filter but im afraid if i do that nothing will happen. and as for our cars with stalling, i have no clue and its a shame because the cavy is a good car...

ive got the same problems!
anyone found a solution yet?

Well, i dont have this car anymore. I bought a 2003 grand prix, i figured i needed an upgrade. But I gave it to my brother and he hasnt been having any problems with it. I cant remember what I did to solve this. But i remember one day i was jiggling wires around under the hood (while the car was started) and it would randomy cut in and out. I found out the post on my battery was broken, and had to get a new one under warranty (even though it was already a new battery). So maybe check your battery post? It seems as though its an electrical problem. Also, try cleaning your IAC, when i did mine, it was completely clogged with gunk. I also replaced the egr (i found a brand new one at the scrap yard, and managed to get it for free). I also then had a problem with the car stalling when coming to a stop, and fixed it by replacing the TCC solenoid. New one costed around $50 i believe. Dont get a used one, i did and i had to end up taking it all apart again because the used one was even worse than the origional.
So there you go, just a few tips.

Similar problem on my '97 Cav., stumbling off idle, when braking for a corner, lights dim, then pop back to normal when car is accelerated. Car runs fine when cold. Idle has become slightly rougher than normal. Replaced fuel pressure reg, fuel filter, injectors, TPS, plugs, plug wires, coil packs, air filter.
Have not had pump pressure checked. No check engine lights. Will check EGR and IAC.
Thanks