Idle/AFR issues when coolant fans kick on.

[forcefed86]

Don't see much on this subject.

Seems when ever my coolant fan kicks on my idle will drop 350-400rpm or so. Also my AFR drops almost half a point. Looks like the ISC is doing it's job it's new. Palm logger confirms it's stepping up and down. Works as it shoudl when fans are not on. No leaks, have pressure tested system.


I'm thinking I need to beef up the ground system going to the fans. Where would be the best place to do this? At the relay? Or directly off the back of the fan? Does the fan relay control the ground or the power side of teh fan?

Thinks I've tried.

Dedicated ground to TB.

3 large gauge wires trans to chassis to engine. Also ran additional larger ground wire from battery to chassis.

 

[1995gsx20g]

i not saying its your problem but if you were to beef up the grounds you would also need a larger power supply. so one is not really worth it without the other..

is the isc port on the throttle body clean?

 

[forcefed86]

Yes, it’s clean. I know the ISC is at least mostly working. I run jakal speed density setup so you can adjust the idle. I can set the idle from 750 to 1000 and it works as it should. I can see the values on the palm pilot change for the isc as the RPM changes occur. When I turn the Ac on the car will want to die unless I have the base at 1000rpm or so. Just pegs out the ISC value.

From what I’ve seen cars usually have decent power supplies. I’m assuming the fans at least have a 25amp relay. Seems like a lot of the time the grounds are over looked. Then again, who knows. Maybe the ISC is just to slow. It is one of the newer plastic models.

 

[docb002000]

Mine will do the same on a fresh re build idles great until the fans come then it tries to die, everything is new/cleaned no leaks