oasis

I have a 01 996 turbo on which I just finished changing the clutch. Upon starting the car after everything was complete the car idles at 2000+ RPM. I checked all the turbo piping for leaks, used a scope to look at all the lines and everything looks good. What I did notice is that if I pull off one of the pipes going into the y-pipe to the throttle body the car starts to idle "normal", if i slowly sneak the pipe back on the car continues to idle "normal" but if i touch the throttle it goes straight back up to 2000+ RPM, if I shut the car off running at the normal idle and restart it goes back to 2000+ RPM. I was worried I pinched a line or pulled something off by accident but can't find anything. Also intermittently when its idling at 2000+ RPM the PSM and ABS lights come on.

Could it be the MAF? I did have the air box out in a dusty shop, could that have caused an issue with the MAF?

TPS? or the check valve behind the throttle body?

Any help, thoughts, comments, and advice would be greatly appreciated.

Thanks very much,
Mike

mffarrell

Did you remove the engine when you changed the clutch or just the transmission?

Chris996

I had same issues. Replaced MAF. when AC/Fan on Idle would go down.

gophaster

Try running it with maf disconnected..if it improves that could be your issue.

Macster

Before you do anytihng else do an E-gas calibration.

The procedure: With the off and your foot off the gas pedal during the procedure turn the key to the on position. Leave on for at least 60 seconds. Turn the key off and leave off for at least 10 seconds. The next time the engine is started the calibration is complete.

If the above doesn't help then sure it could be the MAF. Never had any reason to do this with my Turbo but with my Boxster a "trick" is to disconnect the MAF from the engine wiring harness, using an OBD2 code reader *clear* the error codes, even if there are none to reset all the learned adaptations to their defaults, then road test the car to see if the symtpoms the MAF is suspected of causing are still present.

After you have noted the behavior with the MAF disconnected reconnect it and again clear the error codes and road test the car.

Migiht want to check the hose to the fuel pressure regulator is securely connected at both ends and the hose is ok has no cracks.

Also, if you have the tool monitor intake air temperature and coolant temperature while the behavior is ongoing. You are looking for a temperature reading that differs considerably from ambient. After the car has sat overnight the intake air temperature and coolant temperature and ambient temperature should be about the same.

996tt6156R

Reset throttle adaption. I bet you have a throttle code in there.

oasis

No, the engine stayed in the car. I did however lower the motor about an inch or two, thought i might have pinched or pulled some hose off.

oasis

Turned on the A/C and no change in the idle.

oasis

I'll try that tonight and see what happens, thanks!

oasis

Thanks for the info, I'll try the reset and see if something changes…… fingers crossed

oasis

looks like a friend of mine is going to bring by his durametric so we'll hook it up and see if there are any codes stored, thanks man!

Kevin

Mike you wrote>>

"checked all the turbo piping for leaks"

Did you do that with 14 - 16 PSI of air pressure? Pump the entire intake system to check for a possible leak.

"02996ttx50

^ good advice as always..pressure testing is a lot more comprehensive than pulling on the y-pipe lol

but this timely thread reminded me that while chasing down an intermittent cel and accompanying "idle hunting" issue, i had yet to unplug my maf OR even reset the TB and lo and behold car after doing both, the car idled perfectly w maf unplugged and then back to "hunting" up/down to 1000rpm after driving awhile and resetting the tb ( again ) and re-inserting the maf.

my buddy swore it was the electrical components of the tb gone bad, i didn't ( don't ) believe him and so i am going to throw a new maf at it

still i bet thats "it" and since i cant test the volts of my TB OR my maf! I'm gonna throw a 250$ part at the car and hope i luck out. hah.

i'd freak though if my idle crept to 2k and stayed there even w a/c ON like the OP! good luck w it!

oasis

Did a smoke test on the car today with no visible leaks, could it be a pinched hose or maybe a fuel pressure regulator issue? check valves? Im running out of ideas.

Thanks,
Mike

jimmyrepasi

Check the Bank 1 intake manifold for a leak. Have seen them crack if the engine is lowered too much during a transmission removal. They crack near the stud that holds the aluminum air inlet pipe