Well I finally got one of the project single turbo done. It stats up find but for some reason it idle around 3k rpm? I checked all vacuum leaks and couldn't find any. I try adjusting the idle screw and still it idle around 3k rpm. The only thing I could think of that could cause this would be stuck butterfly. Any ideas why would be appreciated.

 

Bump^^^

 

Beside vacuum leaks what else causes high rpm idle?

 

Ok I check all vacuum for leaks and looks like everythingis capped. I adjusted the idle screw with no luck so want do you suppose causing high idling? The mods: 60-1 turbo kit,pfc (tuned by steve kan,550cc,1600cc, freshly rebuilt with a mild port, and as of now it doesn't have a catback so basically only dp and mp. Could it be a coolant sensor? Anybody experience high idling at 3k rpm?

 

Did you check to make sure you didn't forget a gasket (like between the throttle body and UIM, or UIM and LIM)?

 

I checked all of those gasket and also spread starting fluid to see if it's leaking, all looks good. Would it be a coolant sensor? Is there a setting on a pfc that could do this?

 

this may sound stupid but make sure the throttle cable isn't too tight.

 

I also check the throttle cable and even plugged the brake booster. The only thing that I can think of is the coolant sensor, once I get it I'll give it a try. It idle at 3k rpm and when I spread starting fluid around the gasket and see no leak. Also all the idle screw are turn to where it doesn't touch the anything with the same results.

 

Unplug the ISC and see if the idle will go down, I had a similar problem and the ISC driver in my PFC was fried.

Good Luck
Charlie.

 

I unplugged the ISC and still the same. Also swap map sensor with same result. I bought the car that was use for drag racing. They cut the trigger wires on the ecu and I hook it back up so is there anything that could cause this problem? No matter what I do it still idle 3k rpm.

 

Ill keep thinking away...Has to be the wiring.

 

just get it tuned, it also might be the TPS.. there's a thread in the archives about it.. u might wanna check it out, if u cant find it.. ill find it for u.. let me know.

 

This is prolly stupid also but have you tried adjusting the idle with the air bleed screw under the TB??

 

A coolant sensor would not effect the idle like that. If you are still running the throttle body coolant lines, there is a wax rod that is used to keep a high idle until the car warms up. When the wax melts, it lowers the idle to the normal setting. There are fuel and ignition correction maps in the power fc depending on the coolant temperature, but don't see how that could give you a 3000 rpm idle. Check the sensor per the shop manual. There is a resistance spec. The power fc isn't great at controlling idle in heavily modded cars. You can go into the etc menu and under function select you will see an option of idle ignition control. Change that and see if it makes a difference. You said you already checked for vacuum leaks, so go to the next easiest thing. Check the throttle cable. See if you can manually close the throttle plate any further. Make sure the throttle linkage operates smoothly. Make sure you have ALL the proper brackets that attach your throttle cable (there should be 3) If not, order them from Mazda. I am disgusted at how many cars I see missing these things. I even saw one car where the throttle cable was routed around the driver's side of the motor forward and under the elbow. Check the condition of the cable itself and the gas pedal movement. If the cable is frayed or doesn't operate smoothly order a new one from Mazda. If you have cruise control, make sure it isn't sticking or keeping the throttle from shutting. Check the tps and make sure it is in spec. Unplug the isc and see if it helps. If it does you most likely have a bad isc or a bad driver like charlies7 said. I have seen that happen before and the first time it stumped the hell out of me. Did you mess with the air bleed screw on the throttle body at all?

 

I checked the throttle cable also I unhook it of the manifold. I turned the air bleed screw all the way shut tight. I'm going to replace the uim to stock since the one in the car has the butterfly removed. I bypass the coolant from the rear iron to the thermosat housing.

 

What about the cruise control? If the car has it, check to make sure the cable isn't binding.

 

I toke the cruise cable off already. I'm going to install and different manifold alone with gasket.

 

Well, I highly doubt that a simple vacuum leak is causing a 3k rpm idle. Let us know what you find out!

 

Ok, I found out the problem. For the record I didn't do the installing of this item I notice that when we swap the stuff from another motor my friend installed the LIM gasket and didn't know that there's a paper gasket on the rebuilt motor. He put the metal gasket over the paper( it was in bad shape) so that's why I couldn't find a leak between the LIM &UIM gasket. I toke the LIM out and scape the paper gasket off. Now the car starts up with really low idle so I adjusted the idle screw and now it's idle normal. This is embarassing for me to put the motor together without looking at my friends work. Well thanks everybody for their input.