Idle problem when cold
07-07-2001, 09:12 AM
#1
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Idle problem when cold
My 90 C4 idles erratically-- 'hunts'after starting with the motor stalling at times.
I've been told the idle valve may need cleaning--can someone tell what and where it is.Much appreciate any help.
I've been told the idle valve may need cleaning--can someone tell what and where it is.Much appreciate any help.
07-12-2001, 08:25 PM
#2
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Trish,
Sounds like the same problem I am having with my '94 C2. It surges dramatically when I start it cold and sometimes stalls. My wrench did a diagnostic and couldn't find anything wrong
. It's more of a nuscance than anything so I didn't bother to have him start throwing parts at it.
Let me know if you get yours resolved.
Thanks
Sounds like the same problem I am having with my '94 C2. It surges dramatically when I start it cold and sometimes stalls. My wrench did a diagnostic and couldn't find anything wrong
. It's more of a nuscance than anything so I didn't bother to have him start throwing parts at it.Let me know if you get yours resolved.
Thanks
07-13-2001, 05:34 AM
#3
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Dear Trish,
Firstly you need to tell me if your C4 is standard or does it have lightweight flywheel, clutch, power enhancement (joke) chips etc installed. This is critical to know to really help.
However one thing you can try. Disconnect the battery. There is another way to reset the DME but I am not going to tell you this now because it will not reset if somebody has been playing with adjustments, which by the way never work.
So now you have the battery disconnected, wait for a couple of minutes.
Reconnect the battery (using approved procedures). Then hop in, start up and go for a drive for a minimum of 15 minutes. Do not shut the engine down in this time.
See what the result is.
YOU CANNOT ADJUST THE IDLE. The idle is preset and completely automatic. What causes the hunting is that the DME is getting a variable input which is causing it to vary the idle fuel schedule.
Now some basic advice with these problems. Idel problems are normally something really simple and not too expensive to fix. Do the simple stuff first. Please remember the DME only records faults of what inputs it.
First things to check,
Is the battery servicable
Is the altenator charging the battery at idle. DMEs are quite voltage sensitive. If the alternator is not charging (13.8VDC across the battery at idle) the battery then this will cause this problem.
Is the gas pedal free to move and in the correct position for start (foot off, do not touch, if you pump the pedal before start this problem will occur, only pump pedal softly and a couple of times if the 911 will not start when REALLY HOT).
Air filter is it clean.
Spark Plug leads are they all servicable
Is the secondary distributor belt still in one piece.
When were the spark plugs last changed. What kind of spark plugs were used. Titanium spark plugs can cause this problem when cold.
Ignition coil is this okay.
Now to the slightly more expensive.
Fuel Pump/DME relay can cause this problem.
Failing fuel pump.
Damaged fuel lines
Partialy blocked fuel filter
If all these things come up negative then you have to look at individual components such as,
Engine Temp Sensor (common failure)
O2 sensor
Mass Airflow Sensor
This I know is a long list but start simple and work towards more complex,
Ciao,
Adrian
911C4
PS: Check the connector on the DME which is under the drivers seat is correctly installed.
Firstly you need to tell me if your C4 is standard or does it have lightweight flywheel, clutch, power enhancement (joke) chips etc installed. This is critical to know to really help.
However one thing you can try. Disconnect the battery. There is another way to reset the DME but I am not going to tell you this now because it will not reset if somebody has been playing with adjustments, which by the way never work.
So now you have the battery disconnected, wait for a couple of minutes.
Reconnect the battery (using approved procedures). Then hop in, start up and go for a drive for a minimum of 15 minutes. Do not shut the engine down in this time.
See what the result is.
YOU CANNOT ADJUST THE IDLE. The idle is preset and completely automatic. What causes the hunting is that the DME is getting a variable input which is causing it to vary the idle fuel schedule.
Now some basic advice with these problems. Idel problems are normally something really simple and not too expensive to fix. Do the simple stuff first. Please remember the DME only records faults of what inputs it.
First things to check,
Is the battery servicable
Is the altenator charging the battery at idle. DMEs are quite voltage sensitive. If the alternator is not charging (13.8VDC across the battery at idle) the battery then this will cause this problem.
Is the gas pedal free to move and in the correct position for start (foot off, do not touch, if you pump the pedal before start this problem will occur, only pump pedal softly and a couple of times if the 911 will not start when REALLY HOT).
Air filter is it clean.
Spark Plug leads are they all servicable
Is the secondary distributor belt still in one piece.
When were the spark plugs last changed. What kind of spark plugs were used. Titanium spark plugs can cause this problem when cold.
Ignition coil is this okay.
Now to the slightly more expensive.
Fuel Pump/DME relay can cause this problem.
Failing fuel pump.
Damaged fuel lines
Partialy blocked fuel filter
If all these things come up negative then you have to look at individual components such as,
Engine Temp Sensor (common failure)
O2 sensor
Mass Airflow Sensor
This I know is a long list but start simple and work towards more complex,
Ciao,
Adrian
911C4
PS: Check the connector on the DME which is under the drivers seat is correctly installed.