Alright, I just wired in a new connector and hooked it up. Disconnected the neg terminal to reset everything and then started it up.

The car now idles at about 1000-1100rpm upon start up and runs rich during initial warm up (I believe this is on purpose in the tune). Once the afr gets to 14.7 the hunting begins again... It's not as bad as it was before, but it still hunts probably from 1000 to 1350.

I have two IAC valves and I have tried both and cleaned both and retried them.

Any Ideas???
Could it still be the IAC Valve?
Could it be something wrong with the tune because before we were trying to correct the hunting?
Could it be another aspect of the idle setup?

 

Hey All,

I believe some of you have heard me mention in the past that I have an idle issue. It seems to idle high once the car warms up and then at times it will surge/hunt while sitting at a stop. In the past I have disconnected the evap purge system and that solved the hunting, but the idle would still rise too high after warm up. I have replaced the evap purge valve and canister with no results.Assure that the plumbing for the EVAP system is correct..

I noticed today that one of the wires for the connector to the IAC valve is severed and obviously not connected to the valve. This condition runs up a red flag...I am guess that you are not the OO(original owner), so this vehicle may have been abused in others areas,...Could this be the issue??? I pulled the intake pipe with the engine running and was then able to plug the hole for the iac valve, which instantly lowered the idle back to normal...

I am gonna go to the salvage yard here and hopefully pull a connector to replace mine. Until then though, is it safe to somehow plug the valve so it stops idling high???Probably, but this is not a good procedure.

Thanks,
Shane

An uncontrolled high idle will subtract many miles from an engines life..
I think that this vehicle should be gone over from A to Z...
IMO, the idle air control system is simple and rugged and should last the life of the car...the rubber will deteriorate over time (vacuum hoses), (fume lines)

 

Assure that the plumbing for the EVAP system is correct..

Is there a detailed diagram of how this should be setup???

 

Alright, I just completely disconnected the evap purge system and plugged off the throttle body... I reset the ecu and started the car up (it was still partially warm). It immediately started hunting and was running rather lean, like 16.5-18 afr. Is this normal for a car of this setup??? Should I let it cool down and try it again?

 

Hooked up a different evap purge valve and hose running to the tb with no change.

I was informed that this issue could be caused by a bad ground and I currently am having issues with my left turn signal blinking rapidly and none of the bulbs are out...

So I checked the ground in the trunk and the ones next to the battery. These all seem fine (I even took apart the one in the trunk and sanded everything for good measure).

Could this be from a bad ground on the engine? I believe I have two grounds both connected to the intake manifold... is this correct? How can I test if these are the issue? Am I able to just unbolt them and run a wire from both of them over the side of the bay or somewhere and ground them there?

Thanks for all the help thus far,
Shane

 

I believe there is a ground that goes to the transmission too.

 

Jake,

You are correct that there is a ground running to the transmission that is coming straight from the battery. If this ground were an issue though I doubt the car would even start... is that an appropriate assumption?

 

I had an extended cranking issue (would take about 5-10 seconds for the car to start) on my wife's car till I cleaned that ground up, after that it starts right up. It may not be the problem, but it wouldn't hurt. Keep in mind that the alternator is just grounded to the engine (and transmission) and then to the battery via that ground cable, the alternator and not the battery are the primary source of power when the car is running.

Have you also checked the grounds behind the headlights (both sides) on the inner fenders, I believe that is where the directionals are grounded.

 

Awesome. I'll check all of those. Thanks Jake!

EDIT: Can I bypass the engine grounds by connecting a cable to the battery and then to the body?

 

No the housing of the alternator (bolted to engine and transmission) needs to be connected to the battery -ve terminal, which in turn gets connected to the rest of the cars body for the common ground, if you don't connect the housing of the alternator to anything then you only half the alternator circuit will be connected and it wont produce any power. Unless you meant connect the alternator housing directly to the -ve terminal of the battery, and yes you can do that, it's common practice when tracking down alternator noise with in car audio.

Think of the alternator as a power source (the red wire coming from it being the +ve terminal and the housing being the -ve terminal) the appropriate terminals connect to the battery (think of it as a capacitor rather than a power source), the -ve circuit via the engine, transmission and the thick grounding wire. The +ve circuit runs to the battery via the thick red wire, making a stop at the starter motor on the way.

 

Tons of Motronic 900's hunt for idle, I've found TONS of leaks where the intake plenum meets the throttle body. Be sure that the plastic plenum is tightly pressed onto the TB and that the O-ring is not pinched. This will allow extra unmetered air into the system and cause the AIC to hunt, as the extra air will sometimes cause the engine to rev higher. Just some food for thought.
Motronic is an old style management system and can't regulate much. I've seen lumpy idle from high mileage cars with stretched timing chains causing the timing to be out (distributor).

 

What is hunting? I've never heard of that in the car world before.

 

Thanks for the input tom. The unfortunate thing is that the car idled fine when it was running motronic... now that I am running trionic with a turbo it hunts. I'll check, but I don't think the seal between the intake/charge pipe and tb is leaking.