Persistent low idle after hit restart
03-27-2018, 06:26 PM
#1
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Thread Starter
Persistent low idle after hit restart
1982 911sc
I've changed the WUR and O2 sensor but I have an odd idle issue. I've recently had the mixture set on a CO emissions machine.
The car will now idle around 950rpm, after initial warm up, but, when fully warmed up, if I turn the car off for around 20 minutes then restart the idle will drop to 3-400 rpm. It'll then stay at 3-400 rpm unless I change the idle control screw. The next morning the same scenario will occur all over again.
For example, if I drive off to a pub for lunch the idle will be fine. But when I restart the car after lunch the idle rpms will have dropped to 3-400, even if I drive for 30 minutes (with occasional stalls due to low rpms).
Any ideas?
I've changed the WUR and O2 sensor but I have an odd idle issue. I've recently had the mixture set on a CO emissions machine.
The car will now idle around 950rpm, after initial warm up, but, when fully warmed up, if I turn the car off for around 20 minutes then restart the idle will drop to 3-400 rpm. It'll then stay at 3-400 rpm unless I change the idle control screw. The next morning the same scenario will occur all over again.
For example, if I drive off to a pub for lunch the idle will be fine. But when I restart the car after lunch the idle rpms will have dropped to 3-400, even if I drive for 30 minutes (with occasional stalls due to low rpms).
Any ideas?
03-28-2018, 08:21 AM
#3
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Thread Starter
I have been thinking about the cold vs hot discrepancy in the idle speed. I am thinking about changing the vacuum hoses to eliminate any leaks. I have used Propane to check for leaks but I cannot find any using this method. While shopping for the 3.5 x 7mm tubing I have noticed the distinction between reinforced and un-reinforced hose. I wonder if I might have some un-reinforced hose somewhere on the system that might be collapsing when it becomes warm and less rigid? Would this cause this issue?
03-28-2018, 09:30 AM
#5
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Thread Starter
Nice idea Iceman, however, my wife is still 'adjusting' to the idea of another car and I need to keep her upbeat about it. As it is, I spend some time every trip with my head in the engine bay adjusting the idle so that the car doesn't stall and become thought of as "unreliable" for ever!
03-28-2018, 12:19 PM
#6
Team Owner
the real expert for these is Tony over on Pelican. he know CIS in and out . be warned, the first thing he will have you do is get gauges and tell him fuel pressures. 