I have been having a lot of problems with my idle. In the mornings it was rough untill the car would warm up completely. It would sometimes sound like it was running on one rotor and shake. If I tried drving it would stutter a lot making it almost impossible to drive. Once it was warmed up it would be smoother. It would have an occasional pop while idling. It would also idle high at about 1200 rpm but at night it would drop to about 500 probably from headlights. It would also surge if my lights were off. So today I decided to switch out the Pettit ECU for the stock one. Most of the problems went away. It still idles a bit rough when col but not as bad and there is no more surging, but I still get popping and it will still idle low when the lights are on. I tried unpluging the ISC but that just makes it idle too low when cold and no other noticeable difference. Another weird thing is when I deccel with my lights on it will deccel as normal until 2400 rpms then it gets lighter like I pressed on the gas abit. This only happens with the lights on. I do not believe that the surging is the ECUs fault but something wrong with my car that is more noticable with it. One more thing. The gas filter on my MAP sensor has an arrow that points to the fat end unlike in the vac diagrams. So should I point the arrow to the MAP sensor or have the fat end furthest away? Any Ideas? Thanks

Mods are:
HKS filters
stock twins
all new vac lines and about 2k on rebuild
DP and Catback
relocated battery

ZACK

 

I would start with checking your TPS:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fixed-my-idle-problems-backfiring-bucking-more-170731/

 

check your vacuum lines, thats what it was for me. a serious vacuum leak.

 

I want confirmation on this also, I have mine pointed towards the MAP sensor, not sure if that is right or not.

 

My TPS is at 1.0v and 0.5v so it is in range. I think it is a Vac leak too but my engine was just rebuilt with new vac lines and it already had all metal gaskets so I dont know.

 

So, the motor has run like this since you got it back from the rebuild?

 

Yup it was worse before rebuild. AHAH. I thought it was a leak at the TB because a lot of the bolts were stripped out, but I got a new one and its still like this.

 

Did you zero it out before measuring?

 

Yup. I noticed today that when I turn on the defroster my idle will go up a bit like the ISC is working but when i turn on the headlights it drops a lot.