hey guys, a week and a half ago my car has recently have this problem. It all happened when i was driving on the highway and when i took my exit, it started to surge and stumble and eventually die. When i try to start the car it will sometimes backfire and stalls. When i let it idle, it will just stall out. Now the weird thing is that the car will occasionally act like this but not all the times. I have days where the car runs perfectly fine. No stalls, no surging, no nothing. it runs perfect. Then i have days where it starts to surge and stall out. On saturday i drove to san jose to my sisters house for a bbq and the car ran perfectly fine. but when i was leaving her house, i start the car up and it started to surge and stumble and stall out. I let the car sit there for 2 days and yesterday i went to pick the car up and the car ran flawlessly. Today in the morning i tried to go to school but the car started to stall out. I really don't know whats going on with this car. I recently changed my cap/rotor, spark plugs, fuel filter, oil change, and oil filter. I don't suspect it was caused by the tune up cause the runs fine without having the surging and stalling. My ses light doesn't come on, the surging and stalling unexpectantly happens out of no where. it doesn't matter if the car is cold or hot. i kinda suspect, that it could be maf related or ignition module. Is there any way to test out if there are faulty? I heard that if you disconnect the maf, the car wont be able to run. is that correct?

 

just an update on the car. today my friend came and checked out the car but he couldn't find anything wrong. the car started up and ran perfect. all we did was clean out the iac and we have to wait till the problems comes back again.

 

My car used to surge as you described.

I would check the Idle Air Control (IAC) sensor. On TPI engines, it is located on the passenger side of the throttle body.

Mine was full of carbon and the spring on it was compressed badly.

I believe you can get a new one at Autozone for around $50... GM is around $90.

Hope this helps!

 

Looks like you posted right as I was typing!

 

lol thanks formula. I guess 'll find out in a while.

 

just an update on my car. The car is still acting erratically. Finially the car acted up in front of my neighbor, who is a retired mechanic. He said that it is a ignition problem or the ecm but doesn't where to look at because he doesn't have any diagnostic tools with him. i'll keep ur guys inform on whats going on. to tell you the truth, i don't even know where to look at.

 

The only other time my car ran erratically was when the fuel pump was going bad. Sometimes it would run ok... other times it would stumble and even die.

Unfortunantely, the fuel pump is in the gas tank. I didn't want to tackle that job so I paid GM to do it. Apparently they had to drop the rear-end, exaust, etc. It cost around $700+ if I remember right.

I would assume you could hook-up a fuel guage to the fuel rail and see if the fuel pressure fluctuates, but I have never done this.

I'm not saying that this is the source of your problem, but you may want to keep it in mind just in-case.

Hope this helps.

Best of luck.

 

make sure your distributor cap is on tight. my was not and it was surging also look at the coil.

 

will the car backfire when the fuel pump goes out. Also the distributer is also on tight. I have been busy with work and school so i didn't have time to check out the car.

 

well just an update on my car. My mechanic told me that its my distributer that is causing the problem. Any benefits on an upgrade distributer or should i just get an ac delco.

 

I started having this exact same problem recently with my MAF TPI setup. Happens when its hot or cold, it'll start fine but then it idles rough and stalls out w/ SES light on solid. It will start right back up and do the same thing. Stalls out whenever I put it into gear too. The only thing I changed before it started happening was the oil and oil filter so it had me baffled. I pulled the ECM codes because of the SES light but it just kept giving me 12 over and over (even after clearing codes and going again). I know 12 is the handshake code, but in some shop GM manuals code 12 can be a problem with the distributor. None of my 3rd gen specific manuals mentioned anything about code 12 being an issue with the distributor, so I decided to keep troubleshooting instead of spending $$ on a dizzy. I suspected a fuel issue so I hooked up the pressure guage to the fuel rail and it read 44 psi at idle, dropped 3psi when sarted. So according to the books this is good. My next plan is to replace the cap, rotor, and plugs. If it still stalls then I'll do the distributor. And if that dosnt fix it looks like I'll have to test the EGR/PCV and test for vaccum leaks, and do a compression test on the engine to check for problems with the valves.

 

hmm never heard of a handshake code. can you explain what that means. Also check out the ignition module.

 

When you pull the codes using the SES light it will flash a code 12 (one blink, pause, two blinks) two or three times to let you know its ready to start spitting out trouble codes. People refer to that code 12 as the handshake code because its verifying the ECM is running properly and communicating properly with the ALDL port. When I pulled my codes it just gives a code 12 over and over forever (I only watched for 15 minutes before getting sick of seeing code 12's). Tomorrow I'm gonna be doing the cap, rotor, and plugs, hopefully that solves this problem because I'm not looking forward to buying a new distributor.

 

does ur car backfire sometimes?

 

MAF car, erratic stalling, f/p good, no codes, typically ends up being a MAF relay.

 

I thought about that, but I wasnt sure if I should troubleshoot that route. My clintons manual says if you unplug the MAF sensor and then start the car it will run in open loop mode so input from the MAF shouldnt matter, but I'm not sure if thats correct or not. From reading these forums my best bet is to get the ECM into limp home mode and see if the rough idle continues (at that point input from the MAF would be ignored so a bad MAF or relay would be ruled out). Thanks for bringing it up. Since its very cheap to try one of these tests I think I'll give it a try before swapping out the cap/rotor/plugs (yes I slacked and didnt touch it yet doh!)

Yeah it did backfire a few times, only when revving it up past 2K RPM. But its not a steady backfire or anything and not too loud when it happens.