Idle revving from 1k to 2k rpm at startup

[ArticBoxster]

Hello Everyone,
I was hoping to get help with my idle issue. At cold start my engine would rev non stop on it's own. I had replaced the MAF twice from Pelican parts (didn't help). I cleaned out the throttle (didn't help). I'm thinking it's the idle control valve, but did not want to waste money before I check with on here just incase someone had the same experience and if you was able to resolve it. I was told by a mechanic (not from Porsche) that it's the brain of the care itself that needs to be replaced. Is this correct? And if so does anyone know the cost and if DIY is possible? Thanks

[ArticBoxster]

[QUOTE=ArticBoxster;394996]Hello Everyone,
I was hoping to get help with my idle issue. At cold start my engine would rev non stop on it's own. I had replaced the MAF twice from Pelican parts (didn't help). I cleaned out the throttle (didn't help). I'm thinking it's the idle control valve, but did not want to waste money before I check with on here just incase someone had the same experience and if you was able to resolve it. I was told by a mechanic (not from Porsche) that it's the brain of the care itself that needs to be replaced. Is this correct? I have no error codes. And if so does anyone know the cost and if DIY is possible? Also I don't have any error codes. Thanks

[Jamesp]

Mine revs to between 1 and 2 k momentarily on start up then drops back to 850 idle. My manual mustang does the same thing. I think that's normal. How long does your Idle stay increased? What year / model do you have? Standard or auto? That information may help folks with your question.

[ArticBoxster]

I have a '99 Boxster 5 speed manual. It's definitely not normal because the revving won't stop it consistently revs after starting without stopping. I just ordered the idle valve control and hopes this cures it.

[ArticBoxster]

I fixed it!

[polkfarmboy]

Good for you buddy, I love a sad story with a nice ending.

[Nine8Six]

Did you fix the mechanic... the one that tried to rip/sell you an ECU as well?

[RawleyD]

Great fix, well done sir.

[jb92563]

My idle is also acting up after my AOS incident last week.

It has not been right since then even though I have a new AOS installed.

I get the P0507 code which says its the Idle Air Control located on the Throttle body.

So your fix was to replace it?

I will try cleaning my TB first and if that does not help then it could be a vacuum leak or the Idle Air Control.

I'm wondering what is the best way to check for a vacuum leak?

Any tricks, soap bubbles, smoke, stethoscope or something like that.

I use a mechanics stethoscope and you would be amazed at what you can hear with it. Noisy bearings, etc and is a great way to diagnose and frequently dismiss non-issues. Just not so good on air leaks as the sensor rod is solid for conducting heavier lower amplitude vibrations rather than sound waves of hissing air.

That mechanic nicely identified himself as someone to avoid at all costs as his intentions are clearly not in the owners best interests.

[Nine8Six]

Originally Posted by jb92563

I'm wondering what is the best way to check for a vacuum leak?

Any tricks, soap bubbles, smoke, stethoscope or something like that.

Good home DIY; spray some brake cleaner (or TB cleaner) onto the vacuum hose(s) you suspect. The RPM will increase dramatically if you have a leak.

Smoke is the best but those aren't cheap diagnostic tools :/

Sorry to hear about your issues. Small I hope!

[ArticBoxster]

My idle issue stopped after I replaced the idle valve controller. Took me 10 minutes. Don't forget to use a new gasket. I'd replaced my AOS due to white smoke issue in the past but it never gave me idle problems.

[jb92563]

I tried cleaning the MAF with throttle body cleaner spray, and was getting the P0507 Idle air control value fault and then the P0102 MAF fault, so I thought I messed up the maf.

I was also getting bad readings on the digital dipstick as one day it showed 1 bar down from full and then after a test drive it was showing 1 bar from the bottom. Now its showing 1 bar down from full again.

A good reason to never trust the digital dipstick.

Today I bought some MAF cleaner spray and sprayed the heck out of it in every nook and cranny, and to my utter surprise the car suddenly shows no faults and purrs like a kitten again.

Wow, that maf is very sensitive and picky on what its cleaned with. Seems like any kind of residue what so ever and it will not work right.


Update -
By the end of the first day driving around with the cleaned MAF it started to stumble again on harder accelleration.
This time it throws codes P1126 and P1133 along with the check engine light.

Based on the forum searches its pointing back to the MAF again and apparently when the MAF is on its way out it can sometimes be revived temporarily with a cleaning.

I ordered a new MAF from Pelican.