Thanks for reading,

93 with downpipe and exhaust only. Tested my VAC and boost and both were perfect on the dot. I raced my friend 3 quick runs and then I got the "looping idle". It runs from 1k-2k up and down consistantly.
I checked for disconnected hoses/lines, was all in tact. Even did the "carb spray check" and it didn't change the idle at all. However, when i DISCONNECT my map sensor, the idle holds steady, a bit high, but no looping. By disconnecting that sensor, shouldn't it be doing the oppisite? Took it to a shop and he said it could be the LIM gasket, but we sprayed, and it didn't have any effects at all.
Fuel filter and plugs were changed last week.

Any suggestions would be great.

 

Was the O2 sensor checked out, and have you tried manually adjusting the idle?

 

I tried adjusting the idle, and I just ordered an o2 sensor, doubt that'll help, but i wanted a new one anyway. I also disconnected the o2 sensor just to see what happens, nothing.

After some searching, a lot of people are adjusting their TPS. Nobody has ever touched my TPS before Can it get out of alignment by doing 3 quick runs? Stop laughing!

No really though, I don't think the solution is in that direction. I've searched, but can't find any hints since I've done the checks most people do to hunt down this problem. My VAC is only at 10 now.

What happens if I drive the car without the MAP sensor connected? I don't wanna try, but am curious.

Thanks, please post any ideas you may have!

 

You'd be suprised what adjusting the TPS can do for your car man. I had backfires (a lot at idle/deceleration), looping idle, and boost problems on 2nd and primary turbos. After I adjusted my TPS..EVERYTHING was cured..even the boost issues. Now I am not saying that this is it..but its worth to test it and adjust if nec.

 

Car will run like **** with the map sensor disconnected, it will not only have a vacuum leak, the ecu won't be able to make any changes to anything so it will be in limp mode. You've cracked a hose or popped one off somewhere. What exactly do you mean when you say "looping" idle? Do you mean Loping idle? Or do you mean hunting idle(up down up down up down?
Art

 

Ok maybe hunting idle is what I meant. It revs from 1k-2k up down up down. Again, could the TPS go out of adjustment just from a couple quick runs?

 

Are you saying that you can repeatedly:
1. start the car, warm it up, idle is fine
2. do a few runs, the idle goes bad
Or are you saying this was a one-time event?

It is not uncommon for a car to change behavior as it warms up. If the sequence above is repeatable, it might just be that having the TPS (or something) else out of adjustment doesn't matter until the car gets hot.

However, if the above sequence is not repeatable, I would get a compression test. 10 inHg of vacuum is very low, and the bouncing idle might be the ECU trying to keep the engine running despite a broken apex seal. I have seen the behavior you describe with broken apex seals more than once -- car still runs okay except for a bad idle.

Don't run without the MAP sensor. The ECU would not know when you are boosting, which would cause it to deliver too little fuel, and that would blow the engine. Or it might just run in limp mode and not allow you to boost much at all.

-Max

 

To be a little more clear, the idle bounces up and down right when I start the car, doesn't matter if it's warm or cold.

All was good until I did these runs, now it does it every time I start the car. I'll get the compression check down soon.

Thanks for your inputs