10 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHWhich sensors information affect idle?
Leading reported evidence
Check tire sizes
Suggestion or failed attempt
No successful repair reported for this finding.
0
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0
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1
Discussions
Read evidence and context
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Leading evidence: 'Check tire sizes' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check tire sizes' (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
It should be shiny silver clean inside with no carbon residue.
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Suggestion
It took me 2 days to clean out mine by soaking in throttle body cleaner, wiping, cleaning the inside of the valve with Q-tips soaked in alcohol and moving the valve back and forth with a 9V battery.
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
And another one this morning - delete all the learned values in the ECU/DME by disconnecting the negative lead on the battery for 30 minutes.
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Suggestion
When replacing the MAF sensor or ICV, the ECU/DME needs to be reset so it can adjust to the new learning curve and establish new base values.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
It took me 2 days to clean out mine by soaking in throttle body cleaner, wiping, cleaning the inside of the valve with Q-tips soaked in alcohol and moving the valve back and forth with a 9V battery.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
Time to purchase Foxwell NT530 and run few tests on the sensors and modules (make sure you get Porsche software option) if you have other cars you can add those for another $60, but you'll need to have a PC to connect and do updates on it when you first receive it
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.
10 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Having lot's of trouble with idle on my '99 C2. I have quite a few posts on the issue, but no luck with solving the problem. I would like to know what sensors on the car can send information (bad) to the ECU that would cause the ECU to send bad signals that would impact the idle? Garbage in, garbage out sort of thing. I was going to hand it over to a local independant, but the two I use are both a month out!
Mainly the MAF sensor (mass airflow sensor) and the ICV (idle control valve) on the TB. Is the CEL on? Any codes? What is going on with the idle? Is this the same issue/thread where you have high idle speeds? Year/make/model are needed. Do you have a cable actuated TB or drive by wire?
Yes, it's me, the bad idle guy. 1999, c2, cable, 100k miles. Only one CEL lit, and it was weeks after the problem manifested itself - it was for the MAS, which I replaced. Didn't fix it. Hate to go to a Porsche dealership, and the indie's are all busy.....
Hi Joe,
I'm chiming in because Craig and I have been talking about this back and forth. We both have '99 C2 cable throttle cars with the same symptoms. The idle will stick around 2000-2500 RPM when coasting in gear. It's almost like having cruise control on: if I take my foot off the gas in 4th gear the car will happily cruise along at 40-50 with no additional input needed. If I clutch in the car just sticks around 2200 RPM. You have to "drag" the idle down with the brakes in gear and once you break past the 2000 RPM threshold the car is 100% normal.
It is not going to hurt anything to remove the air filter box from the TB and first, observe the TB plate through the whole range of closed/open/closed/open and so on. You need to check and see if it operates through the whole range without sticking or binding. You need to check and make sure it comes back from full open to the TB stop and the range of movement is smooth. I do believe I read (on the other thread) that the idle control valve was either replaced or at least cleaned. Is it perfectly clean? It took me 2 days to clean out mine by soaking in throttle body cleaner, wiping, cleaning the inside of the valve with Q-tips soaked in alcohol and moving the valve back and forth with a 9V battery. It should be shiny silver clean inside with no carbon residue.
Then what I would do is hook up my Durametric software and measure/map the TB angle while driving from idle to wide open, then back to idle. Something is causing the TB to stick or bind. Could even be a worn out return spring or the TB plate bearings inside the TB. All I've got for now.
Ohh..one more thought...pull the fuse for the cruise control to eliminate that.
And another one this morning - delete all the learned values in the ECU/DME by disconnecting the negative lead on the battery for 30 minutes. When replacing the MAF sensor or ICV, the ECU/DME needs to be reset so it can adjust to the new learning curve and establish new base values.
Here's a quick test that may prove useful.
If your '99' has traction control turn it off.
Also check your tire sizes. If the front and rears don't match diameter wise that could cause problems.
Time to purchase Foxwell NT530 and run few tests on the sensors and modules (make sure you get Porsche software option) if you have other cars you can add those for another $60, but you'll need to have a PC to connect and do updates on it when you first receive it
https://www.foxwelltool.com/wholesal...8aAtnDEALw_wcB
Threads on it in 996/997 forum:
https://rennlist.com/forums/996-foru...xperience.html
https://rennlist.com/forums/997-foru...-vs-nt530.html
Jumpy Chunky has nailed it! I turned off traction control and engine immediately returned to "normal" idle. Drove it in all gears in all speeds, engine always returned to approx 850 rpm. Turned traction control back on, immediately went to high idle of 2500. Now the question is, what is going on with traction control that impacts the engine idle, and how do I get both TC and normal engine idle simultaneouslat
