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whizdumb81

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I have been trying to beat this hanging idle issue i have with my cobra. When I release the gas pedal and clutch the RPMS like to stay where they are.. (Normally about 2.5K to 3.5K depending on how i'm driving) On the gear change i haveta do alot of foot work to make the shifts smooth due to the higher RPMS, And i fear that if this continues I will wear the clutch down if i do not fix this problem.

1. I believe that in past threads they have said one of two things.. either the TB is sticking or the cable is sticking or breaking. RIO said in one of those posts to use the CRC TB cleaner... Can I substitute that for carb cleaner which i have a bunch of...

2. Also when trying the sandpaper to TB thing do you sand the inside walls of the TB or do you sand the edges of the butterflys..

3. Also to attempt to fix the small surging problem that i have what do you recommend cleaning the MAF with (Rubbing alcohol / Carb cleaner / etc.)

Thanks for the help guys:beer:
 
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Quadcammer

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I'll bet money its not the TB, but rather the idle air control motor is screwed.

do you have the stock TB?

clean the MAF with electronics or MAF cleaner only. They are the only ones that don't leave a residue.
 
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whizdumb81

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I just replaced the IAC valve like 1 month ago it's not that and that didn't change a whole lot... Maybe smoothed out the idle a little. Where can I get MAF cleaner? And it is the Stock TB...
 
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Quadcammer

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maf cleaner is available at any auto parts store. autozone should have it.

I doubt that a stock tb is sticking. Is your car tuned?
 
SaleenFiend

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You May Have Gotten A Bad Iac Valve.. Its Happens.. Retest And Clean Tb With Cleaner Dont Sandpaper It, Just Uses Scotchbrite

Caps Lock Sucks But I Use It At Work...

Other Than That Try Your Tps, Do You Have A Mil On? Make Sure Your Mil Is Working Correctly Usually Those To Items Will Pull A Powertrain Trouble Code
 
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whizdumb81

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The car is bone stock minus a Clutch and 3.73 gears... No tunes, no MILs, The problem didn't change much from replacing the IAC, the gas pedal is smooth with no sticky points which leads me to believe that it is the Stock TB causing the trouble. I guess I'll go spray everything up with the proper lubricants/cleaners and see if anything helps.
Since I don't have a MIL on what should i look for with the TPS.. Is there a way to tell if the thing is going bad.. I know my MILs are working cuz I threw a code for an ignition coil a couple months ago... That was fine once I replaced the coils. And this problem existed then so i never got it to throw a code for it.
 
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poopy01

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why not watch it and see if the throttle plate is getting hung up. If not I would also bet on the iac.
 
kezell

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You can also check to make sure that the throttle set screw didnt work its way out and actually holding the TB open a hair. Also like said above crank your car and unplug the IAC valve. Your RPM's should drop to around 500 or it may kill. If the rpm's drop at all then you have a bad IAC.

Let me know after you try this stuff. If this doesnt work there are a few other things you may can try. But these are the simplest.
 
sur_real1

sur_real1

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Mine hangs too, but I think it is in the tune for me. Probably has to do with the idle decay rate. I believe from the factory Ford made our motors do that. But I dunno, I ain't no mechanic :)
 
svtcobra1320

svtcobra1320

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In agreeance with above.....
unplug the IAC after you start the car, if the car dies or idle drops significantly, it is OK...if there isn't any change, the IAC is bad.

Look closely at the TB, can you see that the butterfly is shut ALL the way? Is there some carbon/oil build up around the blades? If so, that could cause the high idle. Carb cleaner will work fine if you don't have TB cleaner(pretty much the same crap, just labled differently)

I made a restricter plate for the IAC to cure the 'hanging idle' problem. Just took the bottom of a Pringles can and traced out the gasket, cut the metal, drilled the holes, sanded the edges a little and installed it. Idle immediatly drops during shifts, inital startup, and blipping the throttle.
 

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