High idle STILL, where to check into next...

[IwantMKIII]

I simply cannot rid myself of this high idle. Its hovering around 1000RPM.

If i adjust the timing via CPS i can get it as low as 730RPM ish but then my timing is WAAAY off, well after (clockwise) the 0* TDC mark on the crank pulley. At 10* its around 1050RPM.

Yes, the ECU terminals are tripped. NO code 51 or any other CEL.

No boost leaks. AFM is reading around 30~31Hz at idle which my understanding is on the higher side when it should typically be around 20~30hz. this is a Lex AFM.

Vacuum is around 20 in.-HG idle and 25 when coasting.

I just recently reinstalled stock cam gears as my aftermarkets failed and marks are lined up dead on with 17 notches in between them.

Should i try retarding each cam gear one notch maybe?

other suggestions?

 

[DegreE]

Clean the Idle speed control valve?

 

[jdub]

^^^ Either that or a pirate air leak in your vac or PCV hoses.

 

[bowsercake]

When you turn your AC on when it is idling does the idle raise even further? I know that it is normal to idle at around 1000 with the AC on.

 

[giterboosted]

wow im havin the exact same problem here, someone help the man out so i can figure mine out too lol

 

[martin p]

mine done this for 200 odd miles after installing the engine, tried to adjust the timing etc tps etc, got it to idle at correct rpm on when setting up, but timing out, so reset the timing to 10deg, then suddenly it settled out to 750 ish rpms!!!

 

[giterboosted]

so what exactly are the most common things to explore when trying to fix a bad idle, i know for a fact that my knock sensor is bad, i have a new one just been to occupied to get around to changing it, think that could be it maybe?

 

[johnathan1]

Probably a small vacuum leak somewhere. But the AC idle increase test will tell you if your ISC is working or not...do you hear it click 4 times when you shut off the engine?

 

[sneakypete]

i had the same problem and it turned out to be a vaccuum leak because the isc valve gasket wasnt properly sealing because i didnt clean off all of the old gasket when i installed a new one.
my idle is good now, but when i turn on the AC, my idle goes down.....??? what could that be? also my isc doesnt click at all when i shut down. ive tryed 2 different isc valves.
any ideas?

 

[IwantMKIII]

i had the same problem and it turned out to be a vaccuum leak because the isc valve gasket wasnt properly sealing because i didnt clean off all of the old gasket when i installed a new one.
my idle is good now, but when i turn on the AC, my idle goes down.....??? what could that be? also my isc doesnt click at all when i shut down. ive tryed 2 different isc valves.
any ideas?

definate possibility....need to try this one out.

 

[johnathan1]

i had the same problem and it turned out to be a vaccuum leak because the isc valve gasket wasnt properly sealing because i didnt clean off all of the old gasket when i installed a new one.
my idle is good now, but when i turn on the AC, my idle goes down.....??? what could that be? also my isc doesnt click at all when i shut down. ive tryed 2 different isc valves.
any ideas?

Then the problem is likely in the wiring to the ISC valve...

 

[sneakypete]

Then the problem is likely in the wiring to the ISC valve...

i thought that too. i even got a new wire harness from toyota a few years ago and nothing has changed. im stumped

 

[IwantMKIII]

I changed the gasket just now, no difference.

I tried pushing the AC button but it did nothing, however keep in mind i no longer have any AC installed.

I've also noticed a tapping noise when i put my ear to the exhaust...weird?

 

[johnathan1]

i thought that too. i even got a new wire harness from toyota a few years ago and nothing has changed. im stumped

Wow, um...then the only things it could be are the Valve itself or the ECU...that is, of course if you aren't throwing any codes.

Test your ISC valve:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=107

I changed the gasket just now, no difference.

I tried pushing the AC button but it did nothing, however keep in mind i no longer have any AC installed.

I've also noticed a tapping noise when i put my ear to the exhaust...weird?

Yea, if you have no working AC system, then I don't think that test will work...

And it sounds like you have an exhaust leak.

 

[IwantMKIII]

new problem.....http://www.supramania.com/forums/showthread.php?t=66903