Rough idle - Page 2

kwren · #16 12-03-2008, 12:31 PM

maybe the electrical gismo that can be adjusted for the idle speed has a bad spot in the potentiometer?
Not sure how, but there is a how 2 on that thing.

TomsSVX · #17 12-03-2008, 12:41 PM

Quote:

Originally Posted by kwren

maybe the electrical gismo that can be adjusted for the idle speed has a bad spot in the potentiometer?
Not sure how, but there is a how 2 on that thing.

There is no potentiometer. The IAC acts like cruise control. It has a target RPM for different coolant temps. It uses the current RPM to calculate whether to send an OPEN or CLOSE signal. Then dependent upon the change seen, it will continue to issue control signals to keep the RPM's steady just like your car's speed if you are using cruise control. There is a much more complicated description if you would like to

PID controller.

Tom

kwren · #18 12-03-2008, 12:53 PM

I seem to recall that Trevor had some information about an adjustment that required sticking pins into the wires and testing the voltage on some "gismo" that could be adjusted to determine the correct voltage output that had something to do with the idle speed. Not sure but too slow idle might cause roughness and stalling??

I could be mistaken because I did not pay a lot of attention because my idle is fine

Maybe I am way off base

Keith

TomsSVX · #19 12-03-2008, 01:21 PM

There is a way for you to wire a potentiometer into the circuit to manually control idle, maybe that is what the discussion was about?

Tom

odepaj · #20 12-03-2008, 02:04 PM

Quote:

Originally Posted by kwren

I seem to recall that Trevor had some information about an adjustment that required sticking pins into the wires and testing the voltage on some "gismo" that could be adjusted to determine the correct voltage output that had something to do with the idle speed. Not sure but too slow idle might cause roughness and stalling??

I could be mistaken because I did not pay a lot of attention because my idle is fine

Maybe I am way off base

Keith

Quote:

Originally Posted by TomsSVX

There is a way for you to wire a potentiometer into the circuit to manually control idle, maybe that is what the discussion was about?

Tom

I believe hes thinking of the TPS?

Maybe clean the MAF and let the ECU reset itself?

I would really look for the simplest answer that is most likely right under your nose.

Thats what our cars usually like to do to us!

Dustin

kwren · #21 12-03-2008, 05:48 PM

does the TPS have anything to do with the idle speed?

TomsSVX · #22 12-03-2008, 05:57 PM

Quote:

Originally Posted by kwren

does the TPS have anything to do with the idle speed?

Yes, the ECU needs to see the voltage of the TPS to generate the idle switch, in which the ECU goes into idle mode. So the TPS does play an important factor

Tom

kwren · #23 12-03-2008, 07:25 PM

there you go!

WestCoastSVX · #24 12-03-2008, 08:13 PM

Quote:

Originally Posted by kwren

there you go!

Keith - go back a few posts, I believe both Tom and myself have already mentioned the TPS was one of the first things we eliminated as the cause.

Kinda unfortunate too, because if it was working wrong, it probably would have explained the idle problem AND the 2-3 tranny flare.

kwren · #25 12-03-2008, 09:22 PM

Sorry, I missed that

I am always doing 3 things at once

Good interchange... all about learning!

Thanks,
Keith

degeso · #26 12-05-2008, 07:21 AM

clean and check your air filter and check all vac hoses

degeso · #27 12-05-2008, 07:34 AM

its not electrical the intrument panel would flash if you alternator was going bad you could need a new pcv valve its an intake or fuel/exhaust problem check your fuel preasure regulator while your at it. there are a **** load of vac hoses under that intake manifold can only be replaced with svx hoses if not they crimp been there done you also may need a new iris check valve.
one more thing to check would be your maf sensor i took my air filter off and drove down the block and my car idled funny and almost stalled but didnt clean that *****

WestCoastSVX · #28 12-05-2008, 10:35 AM

Air filter is brand new.

PCV valve is brand new as well, but.... Right after the engine got all put back together, I sprung a coolang leak in one of the hoses under the manifold. Happened right at a race shop that was just goin to do an alignment. They seemed capable of fixing it at least, but who knows if they got everything back together right after putting the manifold back on. But I was wondering if the new PCV valve could have been ruined by the coolant spraying all over that area? Or is it sealed off from outside influences?

Tom's care package includes another MAF, so we'll be checking that as well when it gets here.