Car won't rev past 2k RPM with a/c off. a/c on works fine.

[spags]

Hi,

I recently bought a single owner, rust free 1984 325e and I'm in the process of working out all of the kinks.

The car stood for about 10 years and all of the intake rubber is basically gone. It's got some creative wiring done to the A/C and the speakers (which will be reverted back to stock shortly). The A/C has lost it's charge and i'm planning on doing a proper R134a conversion.

It's got one issue I can't still put my finger on. When the A/C is off. The idle is rough and hunts between 700 and 1.5k RPM and the engine refuses to accelerate past 2k RPM. When the A/C switch is turned on (not the blower though just the two switches). The idle stabilizes a bit and the engine will go up all the way to the earth shattering 4k RPM redline eta's are known for.

This weekend i will replace the hoses, make sure the TPS is working/calibrated, and start undoing the ghetto wiring job done to the A/C. I'm hoping this will fix it but to be honest i don't think that will do it. I don't see how turning on the A/C will make the engine work any better.

Any pointers at what else should i look at beside intake hoses, TPS, and fucky wiring?

[tomstin]

Strange, but there is a wire that goes to the Idle Control Module (ICM) that activates when the AC is on. With the creative wiring that may have gotten screwed up and possibly messed up the ICM???

[spags]

Thanks for the reply.

I checked the TPS and it's was working fine. So that's not it. I'm not going to be able to work on the engine until the vent hose arrives.

I'll update status then.

[Pavane]

Might take a look at the wiring going to the idle stabilization relay and see if there's any broken wires.

Mine did this just recently (couldn't accelerate even when the gas pedal was floored) and the RPM input wire was disconnected from the relay connector. I believe its the small, blue wire.

[spags]

Kind of a late reply but I eventually found the problem and didn't see it posted anywhere so here it goes in case anybody runs into this problem.

Root cause was that somebody had messed with the idle control module plug. The wires from the TPS and the temp sensor where disconnected from the plug. Once this was restored the problem was fixed. I'm still having issues with a high warm idle but the original problem of it not reving without the a/c switch on is fixed.

I don't know what would posses somebody to mess with this wiring since nothing seems broken.