So I had bought a scanner for my bird to help me find my surging prob. If I let the car idle for an extended period or let it sit somewhere where it could heatsoak under the hood after a while it would surge almost immediately afterward. I have discovered that my IAT would spike to 100+ degrees and the surging starts. When it surges it will bring air past the IAT and the temp will go down to 95 or so and come back up b/c the surge stops. Then it heatsoaks some more back to 100 and the cycle continues. I believe that this is the culprit (at least for me, that and one of my 02's goes to 4 mv for a couple second every once in a while) I do not know why the car wouldnt have done this when it was new but it is related to it somehow i believe. The tps doesnt budge when it surges, rpms go up, o2's fluctuate, iac i dont remember (another big player i know) everything looked ok, except that iat shoots up. When the IAT temp goes up the car runs crappier too.

ANyone think i have a valid point? Do you see what i am talking about with the cycle thing of the IAT? when i am cruising it goes down to 60-80 degrees. It only surges on long stops or when it can heatsoak. BTW the car doesnt miss at all.

 

Don't know if that is actually causing your problems, but everyone's car is going to experience the same things you see with your IAT. It's normal for it to sense the temps you see during the conditions you describe.

 

Ohyeah, i know it is going to be like everyone else's car, every car will heatsoak under the hood during traffic, but what i am saying is that it only surges after the temp reaches 100+ and goes back down b/c the surge causes more air to go past the sensor, cooling the intake air and the sensor. The temp goes down to 95 and a couple of seconds later it is back to surging. See what i am saying? That is the only thing on the scanner that is suspicious to me. I know if i am driving down the road it will go down and if i press the gas it will drop even more. I dont know why it would do this after almost ten years, but it is. I thought maybe my pcm is bad? It only happens after a specific amount of driving.

Are there so few replies b/c there is a fix? I havent been on the board that much lately....

 

I am having the exact same problem that you are having. I would hope the IAT would fix this problem as you describe, because it has been driving me crazy trying to find a solution to this. If anyone else has any input on this situation it would be greatly appreciated.

 

Yeah, well i found my problem, I think. The Opti. My scanner is telling me that wehn it surges i am at 5700 rpm, when it is more like 1200 or so during the surge. After two years of searching, I am pretty sure this is my problem. I think it ruined my 02's in the process too, though.

I dont know how the IAt is connected with the opti, but I am sure somewhere in the timing curve it has bandaged the problem until it relearned or something. WHo knows...

Funny thing was, the problem was right infront of me, i just never took the time to look at the rpms *on the scanner.*

 

man that was an old thread, didn't notice. Anyway I'm pretty sure it wouldn't have been the opti in my case though unles it's just a huge piece of sh**. Because I replaced it maybe 2 years ago and put no less than 20k miles on it since then. I really don't want to go through the 300 dollars and pain of replacing it if that really isn't the case. Let me know what exactly you were noticing on the scanner and I'll maybe get one to check it out. Thanks