11 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
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Discussion summary
YOUR RESEARCHEngine dies at low idle with A/C on.
Leading reported evidence
Check also
Suggestion or failed attempt
No successful repair reported for this finding.
0
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0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Suggestion
If ICV works, check for voltage at plug and go from there...
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Suggestion
Do a search in this forum for "clean idle control valve".
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11 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Newbie, first post. I bought my first 911 last week and am working out the bugs. All help is appreciated. I'm a shade tree mechanic at best and more familiar with bikes.
1999. 996 coupe, manual. 92k.
Engine dies at low idle /low speed with A/C on after warming up on a warm day (75f). Turn off A/C and all is well. It is an issue in parking lots and coming to a stop with clutch in.
According to the tach, it is idling ~850 with AC OFF and ~600 ON.
Any suggestions? Thanks for any help.
These cars get an input from the AC controller that tells the ECU to bump up the idle speed when the AC compressor is on. You need to find your if that signal makes it to the ECU. I am not sure if it is a wire or a CAN message. A scanner might be able to see.
As others have suggested, likely to be a problem with ICV or its signal.
Easy to check ICV with a 9v battery.
When A/C compressor kicks in, the extra 5-8hp load bogs down the engine. So the ICV is suppose to kick back up the idle to 750-800 rpm or so....
iirr, unplug the valve, remove it. Middle terminal is ground, one side terminal closes valve other side terminal opens valve. Easy to see inside of valve when its removed.
Use some jumper wires for this test. Connect neg - 9v battery terminal to middle ICV pin, touch +positive from 9v battery to either side of valve and watch it open/close, do same to other side terminal. If no action from either terminal ICV is bad, (gummed up, seized, or whatever). If ICV works, check for voltage at plug and go from there...
After a thorough cleaning with carb cleaner it did not respond to the battery test. Reinstalled and it seemed about the same.
This is a Bosch part. I'm curious if those were OEM? Or if this has already been replaced at some point.
I've looked at replacement ICVs and they range from $20 to $225 for aftermarket. Any recommendations?
After reviewing the price of the part I decided to give it another go. This time I realized the valve could be opened with a screwdriver when working properly. Mine was rock solid and didn't move at all. No wonder the battery diagnostic was unsuccessful. So I invested more time saturating the valve with carb cleaner and it finally moved a bit. From there things moved quickly. Didn't take long and the valve was snapping back in place because it is spring loaded.
Installed, works perfect. Bumps up RPM when AC compressor kicks in. No more stalling in parking lots.
Thanks for all your help.
