XclusiveAutosports

Hey guys, as some of you may know, I have recently gone turbo and am currently working out the few small bugs that remain. One problem that I have had has been setting the idle. I am now running an AEM EMS and I want to make sure that before I go blaming the idle maps for my problem (I have had them looked over by two tuners and both of them don't see why the car would idle so high according to the maps), I want to make sure that it is not a mechanical problem. Basically, when my car is first started and warming up it, the idle is dead set at 1,000-1100 rpm, but when the car warms up the idle will go up to 2400rpm and remain there once the car is warm. I was thinking that the problem could be one of three things, and would like to hear your feedback on this or if you can think of anything else it could be. I think that is could be:
1) I didn't bleed the coolant system correctly and I still have air in the lines... could this cause the very high idle?

2) My throttle cable is not adjusted correctly... but wouldn't the idle always be high from startup and not just when the car is warm?

3) The EMS maps, but I really don't think that this is the problem because I have looked at every idle map in the software and none of them even come close to over 2,000rpm anywhere across the coolant temps.

Does anyone have any ideas or advice because I would really like to diagnose and fix the 2400rpm idle problem. Thanks.

Spec_Ops2087

Well I don't know a fix but I don't think coolent effects idle only your temp bars. Also if your throttle cable was screwed up it would always be at a higher idle I believe.

Sounds like a EMS / MAP problem but I'm not very technically inclined

SIIK2NR

Almost positive it is not Mechanical.... It's your map....

Tim

Wisconsin S2k

IAC motor?

Race Miata

I don't know if EMS controls the IAC or not. But if it's anything due to electronics it's because it ends up turning the IAC valve wide open. With just bad fueling/ignition-timing alone, you can NEVER get 2400rpm without opening up intake of air.

If you didn't bleed coolant correctly, it CAN definitely result in your symptom. You can have enough coolant drowning the engine temp sensor (3 bar) while a pocket of air at the cold idle valve turns it wide open.

Check small coolant hose going to cold idle valve. Is it warm? Check coolant path. Is is possible that during turbo installation you removed and replaced the coolant hoses in the wrong places?

Trip

Check the TB and see if the butterfly is operating properly and there is nothing in its way to prevent it from shutting.

I don't know if this could effect idling. Check for any vacuum leaks on the Intake manifold side.

Depending on your setup, you can sway to the OEM ECU and re-check idling to eliminate the mechanical side.

pushinlsteg

check ALL vacuum lines, and the IACV or whatever these cars have

WalkingDrunken

I would say IAC. If you can swap with someone else's IAC that'll tell you. And it's a quick swap to make sure it is or isn't the problem.

I don't think it's your maps either. A lot of the time idle control is never touched on the maps after it is set once. If you want I can take a look at the map for you really quick and tell you.

Just don't know about the cooling system. Seems like race miata covered that pretty well.

XclusiveAutosports

Thanks for all of the advice guys, there is a lot of useful info in this thread for me to try out. I just tried to bleed the coolant system by running the car from cold (I let it sit overnight) with the radiator cap off and let it cycle the fans on and off three times from idling. Everytime the fans kicked on the thermostat opened and the coolant levels dropped a little bit and I topped it off. Hopefully this would have bled the system, but I have never done it before so i'm not positive. I am waiting for the car to cool down so I can take it for a spin and see if that solved the problem. What is strange is that when the car just idles and the coolant gets hot without driving the car, it has no problems with the idle and no matter how warm the car gets it will idle at a constant 1000rpm, but if I were to drive the car it would start with raising the idle to 2400rpm again. Next I will check the vac lines for a leak, but my boost gauge looks fine around 22 inHg when the car is idling and I don't hear a leak so I doubt that is the problem. I am praying that it was air in the coolant system, but when I take the car for a spin I will be able to see.

Race Miata, where exactly is the coolant line that goes to the cold idle valve? Is it the hose that is on the side of the intake manifold behind the throttle body by the driver's side fender? I was feeling those hoses and they didn't feel too hot, but it may have been because the car was only idling. When I installed the turbo basically all I did was take the coolant line that goes from the head to under the throttle body, and I cut it and ran a loop that goes through the turbo and back to the head so a line isn't crossed.

S2Krev, what is your email, i'll send you the map to make sure it isn't the problem. Thanks guys.

XclusiveAutosports

I just did some research on the forum and it seems like people who had problems with the IAC had a sporatic idle, but what I don't get is that the idle will stay fine at 1,000rpm, but when the car is driven and it warms up then it will shoot up to 2400, can it be still be the IAC? Also, what's the best way to check for a vaccum leak aside from listening because I don't hear one?