U have a 98 z24 with 123k miles, with a 5 speed. When i start it up lately it barely wants to start and it idos from 400rpm to 900rpm. when i give it a bit of gas it melows out, around 3k. Oils been changed, fuel filters been changed, and so has air filter. Just put 30$ in gas, so I know it has gas. My dad thought it could be some kind of sensor. After 10 seconds it seems to semi idol better, though not good. Could sparkplugs do this? I assume they have been changed at least once, but we have not did it. While driving it seems to be ok, though the power occasionaly stops and comes right back on so slightly its hard to notice. Any help would be greatly appricated. Thanks!

Also, i posted in another thread but my car doesnt stall it just runs like poop, so i thought id start my own.

Could be a plugged IAC valve. This will cause starting issues, mainly cold start stall, then idle be low and roll.

You would an OBD II scan tool to see IAC count at idle.




- 2004 Cavalier - 124k, owned since new

I have the EXACT same problem with my 98 Z24 122K miles. But i dont think the mileage has anything to do with it cuz its done this since i brought it when it had 72K. Does yours idle fine after its been started for awhile. Cuz mine is only when its started then after a lil time its fine. It doesn't do it when i am driving or stopping. Also, is your check engine light on? Cuz mine it not. I have asked numerous times what is wrong with my cavy no one really knows. I have tried a few things so far such as: replaced the spark plugs & boots, replaced the air filter, fuel filter, Intake Air Temperature (IAT) Sensor, Manifold Absolute Pressure (MAP) Sensor, Throttle Position (TPS) Sensor, and the Engine Coolant Temperature (ECT) Sensor. My next guess is my O2 Sensors.... if you figure it out PLEASE LET ME know! Thanks & Good Luck!

Honestly, every time i talk to people who have our "problem" its a 1998 cavalier 5 speed.. i swear something is wrong with the computer system for that year.... no one can really give me an answer to what the problem is. And i dont wanna take it to a dealer cuz they are not gunna know either just play a guessing game just like i am right now.

i had a very similar problem in my 95 monte carlo that i used to own. i put in some high concentrate fuel injector cleaner, and it cleaned up the problem. i had to use that stuff on a somewhat regular basis in that car (about every other fillup sometimes a little less), but my problem was worse at cold starts, it would start and then shut off right away, and i would have to start it again. if i pushed the gas for about few seconds it wouldn't shut off on me. worth a shot to try this, its not like the injector cleaner is expensive.




Goal is to make my N/A Auto faster then a manual without doing engine internals

Hello there Nathan Nighbert, Does youre car have check engine Light on?. I would try using apropduct called Sea foam, You could be having a carbon issue build up, Ive used this product a few times already, Its cure a few issues I had with idle problems.


Good Luck

My car does not have a light on. Where is the Iac valve? I have herd of sea foam and herd mixed reviews. Kind of scared to try it, but im scared im going to be stranded some place so i mite have to give it a try. How exactly do I use seafoam, put it in gastank? I have used fuel system cleaner before and im not sure if it worked or not. The car used to start werid like this once every 50 starts. Now it does it regular. If the orginal plugs were still in there, that could cause problems until the computer gets the fuel mixture right, right? I just need a quick cheap solution. Could not have come at a worse time financialy. ( new iMac comes thrusday). Also, what are the names of my sensors that I can replace.

Your comments are appricated.
Thanks

Well I just drove 30 miles to Autozone and got some Seafoam. Put the whole thing in my gas tank. Car still starts like crap and idols really crappy. The car is warm and is still idoling like Poo. Seems to sputtor now. Blub Blub..Blub. I could barly tell it was doing this until I just went around to the back of car. Bosh -4 plugs were 5.99 each so I think ill grab some of those on my way home. I also had this thought, wouldnt a sensor trigger a light? Since I have no lights It should be injectors/plugs or something. Thanks Everyone.

Yes if its a sensor the check engine light "should" come on.. but with all the treads on this problem i really think it has to do with the year and 2.4 engine.. i swear GM messed up..... HOWEVER, i had a 1996 cavalier 2.4 and the CAR NEVER DID THIS!!! you figure that out....???/

well Nathan Nighbert, Just dont blow a whole whack of cash on trouble shooting the problem, Just look at if youre car hasnt had a tune up in a while or, My guess would still be you got an issue with IAC valve, That for sure could give you problems with youre idle, Usually I would make sure you clean out youre throttle body really good with some cleaner, Then check for vaccum leaks, Would hurt to get a fuel pressure test done too on the fuel pump.

Good Luck

if it's a plugged or stuck IAC it will not set a code. Before changing your plugs, pull them first and check to see if they're fouled. Honestly my first step would be to buy some crc throttle body cleaner, pull the iac valve, clean it and your throttle butterfly while you're there. If that helps, but the problem returns, i would next replace your iac (idle air control) valve.


JBO Stickers! Get yours today!

Well I droped the car off to our mechanic last nite. Running so rich it almost makes me sick to drive. Have to keep the rpm's above 2500 or it lurches fowards. When I told Jermey(mechanic) what was wrong with it, he guessed idle air control valuve. He said he would put it on the comptuer to see whats up. He also questioned my fuel pump, and said hes going to see what the PSI is. Last time I had it done it was at like 68, I think. Is 68 good? Jermey always takes good care of us at a good price. Hopefully he can get it running correct today some time and ill let everyone know whats wrong with it.


Thank you so much for responding.

Just got my car back... and its not completly fixed. He found out that my coil packs were junk and some other white peice. spark plugs were orginal (123k), and that injector #3 is crap

So i Guess on thrusday im going to have him change the injector. He also wondered about the PCM but feels that 100 for the injector and it shoudl be in. Spend 250 today for him to go through everything.

Kind of depresed cuz it still is smokey and not runnin like I want it but what can i do?
Gonna try and see if i can get that injector done this weekend if possible.

So its still idleing like crap after all that soo far??/

Ya, still ideling like crap, got to get the #3 injector replaced. Hopefully it isnt the PCM.

OK, replaced te injector, and that still didnt fix it, then found out that the fuel pressure regulator was letting fuel in. It was stuck open, thats why at 3k rmp it would run fine. Also found out that my SES light does not work.400 dollars later my problem appears to be fixed and my z is running like new. So to everyone that has this problem, I changed, coil packs, sparkplugs, injector, and fuel pressure regulator. Not cheap, but it runs nice.