[ds968]

We've had a few days here recently with low to mid 80s temps, and when that heat radiates off asphalt combined with our cars' engine heat, it translates to significantly higher temps at play for the 968 which typically does not do very well in warm weather to start with.. An while my six speed never manifested this symptom, the tip's RPM in neutral gear, or in D ( or R ) when you put the brakes on , drops by a good 100 rpm , maybe even 150 or so below its "normal" level in colder weather . So when I have my AC on ( which is about 99% of the time I drive the car ) and come to a stop it comes within a fraction of second of stalling so I have to throw it in neutral just to keep the engine running. What the heck is this all about ? Ambient temps affecting tne RPMs ?! What sensor or part could be the culprit ?

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[Waylander]

Could be a bit of a duff ICV, you can buy a cheap alternative for testing its from a Hyundai Lantra 2.0 on eBay for about $45 instead of $350 from Porsche

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[ds968]

If the installation is very easy, $ 45 is most certainly worth the " test " .

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[flash]

lol - nope - actually really a bit of a pain in the ass to change.

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[ds968]

Ugh.. I was hoping a screwdriver or a pair of pliers ( the extent of my tools AND skill set ) and a five minute removal / installation from the top , and without disconnecting anything else would suffice. Yeah right , wth was I thinking, it's a Porsche, not a 1974 mustang., lol. Maybe I'll just have my mechanic do this . So the consensus is that the ICV is most likely tne issue ? Again what's odd to me is that it ONLY does this in hot outside temps, never when it's below 75 F or thereabouts, so I suppose tne ICV reacts to heat variations ..?

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[Waylander]

It's not that hard unless you have a supercharger in the way


You could try cleaning the maf the car does not have an air temperature sensor as such, uses the temp sensor at the front under the top hose, the oil temp sensor and the MAF for volume


The water temp sensor is easy to change and quite cheap

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[flash]

did we upgrade the tip kit to stage 3?

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[Waylander]

?????

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[ds968]

Waylander: a supercharger IS in the way. :-(


Flash : Yes, we have. Does that make a difference ?

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[Bulti]

FYI, the rubber "dampers" that hold the ICV are NLA. Just so you'd know :-)

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[flash]

ds - actually that rules out one potential cause

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[ds968]

I just have to move to a cooler climate, that'll solve the problem ! :-). So I drive to work in the morning and the car is perfect. Come lunchtime and the midday heat, the gremlin shows up. Tested this again yesterday..in N gear and in P the idle ( even in high heat ) rpm stays exactly where it is when it's cold out. So why would it drop only in gear and when I come to a stop, any more so than the level to which it usually drops under the same circumstances in cooler weather. Has to be air related doesn't it ?

I just cleaned the MAF a few months ago, but it doesn't hurt to do that again, though I suspect that won't be the issue..

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[flash]

it's likely due to airflow through the ICV.  if that hose is at all kinked, it won't get enough air.  

 

similarly, if the O2 sensor is old, it won't get a good reading.  those things only last 60k on a normal car, and less on a supercharged car (richer startup mixture and higher temp exhaust)

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[ds968]

Ugh, quite a few things to look into.. Luckily I can at least check the hose kinks, if any , and straighten them out .. No idea how old the 02 sensors are. I'll look at the records.

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[Waylander]

Only one O2 sensor, complete bitch to remove, normally requires extreme violence

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[ds968]

The O2 sensor in my six speed is the original one with 115 K + miles on it now and still working fine. I guess I need to count my blessings on that one . Anyway, I spoke to flash, he gave me some tips on looking into a few other things first so before I plunk down any cash and also put up with my mechanic's bitching and moaning about Porsche's design making any repair job a PITA, I'll tweak some things around . Because this car was vibrating way too much and we eliminated the possibility of motor mounts as the cause, I raised the rpm by about 150-200 rpm above norm and although that mitigated the vibration substantially and the car runs a great in temperate weather, perhaps the lack of sufficient cold air during hot outside temps with the added load of the higher rpm while in gear and with the brakes on could have an adverse effect and cause the rpm to dip quicker and not recover fast enough so it stumbles ..easy way to test that so I brought the rpm down by 100 or so and we'll see how it behaves tomorrow, or whenever we have the next heat wave .

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[flash]

115k????  i'd be willing to bet the car would run better with a new one.

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[Waylander]

115k????  i'd be willing to bet the car would run better with a new one.

So would I, they still work but the reaction time is massive and inaccurate

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[Bulti]

And exactly how much violence does one need to apply to get it out? ...And which type of violence? I probably could arrange for a few football hooligans, but that would scratch up my paint, lol.

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[Waylander]

To change mine it required a 22mm ring spanner and a club hammer bashing it backwards and forwards, the big problem is it always chews the threads and to clean up the threads you have to remove the cat section of the exhaust


Not a job I want to do again, it took about 3 hours in total

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