16 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHDo 996's have an automatic choke?
Leading reported evidence
Clean sheath where the two cables meet
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
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Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
Also opened and cleaned the sheath where the two cables meet, cleaned and confirmed that the rear cable operated smoothly.
Leading evidence: 'Clean sheath where the two cables meet' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check intake/vacuum leaks' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion · Original poster
DBJOe: Thanks for the help, I am checking on each of your possible solutions.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion · Original poster
Still got a high idle, usually in the first twenty minutes of running, despite engine being up to temperature.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
16 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
1 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
I removed, cleaned, and reinstalled the air idle valve, then replaced it completely, and still the issue persists.
I have a '99 c2 with 100k miles. It's engine/throttle developed a sticking point around 2200 rpm when the car was cold started, and for 20 minutes or so thereafter. I removed, cleaned, and reinstalled the air idle valve, then replaced it completely, and still the issue persists. It does not "stick" anywhere else in the rpm range, which makes me think it is not a throttle cable issue. Throttle body is clean as a whistle. I am wondering if there is an automatic choke, or if that is the purpose of the air idle valve. Any other ideas would be appreciated.
Thanks
Not true at all. A choke is designed to fatten up the mixture when cold; the IAV only regulates idle...which it does all the time, not just when the car is cold (like a choke).
;-)
Are you sure it is not a throttle cable issue? You had to pull the TB to get to the IAV. I found one time that I had not snapped the throttle cable and the plastic cable guide on the TB back in correctly, so all I got was high idle. Took off the cable from the TB and gave it a good tug. The cable snapped into the plastic guide, and the guide snapped into the TB housing. Everything good after that.
Yes that's true but how the hell am I supposed to explain to the PO that the ECU does the "choke" part when he is asking questions that no one with EFI should be.
Imo000 - This forum is to help educate fellow porsche owners, so ease up on the condescension, and don't offer me any more "advice" I thought Canadians were supposed to be nice.
DBjoe thanks for your helpful suggestions. As I mentioned in earlier posts I replace IAV. Previous owner had installed and then removed performance plenum, so I was assuming there was some sort of hang up as a result of that, I disconnected the rear throttle cable, and it did in fact snap into place with a tug. Also opened and cleaned the sheath where the two cables meet, cleaned and confirmed that the rear cable operated smoothly. Still got a high idle, usually in the first twenty minutes of running, despite engine being up to temperature. It has a catless exhaust system - sending bad signal to ECU? Does the coolant temp send a message that somehow impacts the idle?
I would remove the air filter box so you have clear and open access to the TB. I then would run the engine and observe the operation of the throttle plate through it's entire range of operation. It must be hanging up somehow. Do you have Durametric? It will show and log the throttle plate angle while running.
Craig, you're obviously new here - and to your 996. You have to understand that many of us have been here/around these cars for a long time - sometimes this comes through as impatience. Generally speaking Imo000 is knowledgable and well intentioned even if he comes across as gruff sometimes. In a word; Yes the 996 sort of has a "choke" condition - it's actually the ECU controlling the fuel air mixture until the diagnostics see certain conditions, at which point the idle drops from around 1000/1100 rpm down to around 750 rpm (and hopefully stays there)...
Dporto: Thanks for the message. 5 years on this site, I've owned 3 996's, wrenched on all three. Also a 968, an '81 SC, 944 s2, two of which I rebuilt from non-running. Not a rookie, not an expert. I depend on this site for advice, it is tremendous resource. I am not embarrassed to ask questions some might find stupid - I know what I don't know. These are "teachable moments" not opportunities for ridicule in an adult world.
I am wondering if the coolant temp sensor is sending bad info to the ecu, 1) because the sensor is bad 2) because the car has a third radiator and low temp thermostat . Would the ECU then still send a message to keep the rev's up 'cause it doesn't know the engine is warm yet? This would not explain the now common occurrence on the revs being stuck up at 2200 or so.
