Hi guys, so I've been trying to chase this problem for the last couple months it seems like. I was hoping to just have the new motor together and replace this bugger but its not going to be ready within the next couple weeks so I need to figure this out since I'm still driving the car.

I can't really describe the problem as anything more than a random, sporadic surging. It will happen in the middle of driving but I notice it most when I am decelerating at a red light. The car will surge down to ~200 rpm and then up to ~1500 over and over until I give it gas or it dies. And then its just fine?

This can happen 2-3 times a day or once in two weeks. Needless to say I had to coast into my spot a few minutes ago at work.

Any ideas?? I just replaced the TPS and no change.

Thanks guys.

 

Put a REAL scan tool on that vehicle, tell us about commanded idle speed, how the IAC reacts, fuel trim (short- and long-term) and O2 voltage and crosscounts.

 

Sorry boss, I wasn't ignoring you. I had to just park the car for a little while. I work 2 jobs so I just haven't had time to mess with it this week. I've got a buddy at the shop down the street that said I could hook it up but they only work til 5 so I'm going to try to get it there tonight.

It just seems to randomly miss at any amount of throttle. I will hold consistent throttle and then its as if I just let off really quick and get back on. It did it for most of a 20 minute highway drive earlier this week too.

What kills me is that some days its just fine...

Any tips to try until I can get it on a scanner?

 

check your injectors if you have a multimeter.

 

I'll do that when I get home from work this afternoon.

 

It can't hurt to check all the vacuum lines off the tbi. It's probably not them but here's the diagrams just in case. The one going to my maf sensor was broken and had similar symptoms, but constant not just every now and then.

 

First one is manual trans second is auto

 

Mine was doing the same thing. I was at wits end so I just re-did all my vac. lines and yes that was it.
Good Luck

 

this is a great image but there is one from the canister to a vacuum ball underneath it as well as if your car has cruise control check that vacuum line as well. Yes vacuum lines are the best cheapest place to look first as these lines are rotting out on our old cars goodluck and hope you find out what it is and let us know

 

Maybe the egr is getting vacuum at idle sometimes. Plug it off at the valve & drive it a couple days.

 

Thanks for all of the great suggestions guys. I'm still trying to sort it out, I've been pulling 12 hour days and just haven't felt like messing with it much, but I'm finally back to a somewhat normal schedule.

Info to come!

 

Anything new you one of left