Cold Start problem
09-04-2001, 11:54 AM
#1
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Cold Start problem
I have a 1992 C2. When the engine is cold, it doesn't start immediately. It almost always starts on the first attempt, but it seems to take more then a normal amount of revolutions on the starter before it catches. The RPM's also drop for about a second when it does start. Once it gets by the momentary stumble at the start, it runs great. I just recently had the plugs changed, new fuel and air filters and the caps and rotors inspected.The car starts fine, when the engine is hot.
Any suggestions on what it could be and how to test for the problem?
Any suggestions on what it could be and how to test for the problem?
09-04-2001, 01:20 PM
#2
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Hi Jon,
I would start by looking at the battery and ensure that it has enough cranking charge.
Try recharging it overnight and giving it another go. Is it the correct battery.
Is the engine in good condition? compression etc. Has this prob. just started.
Has the oil been overfilled recently. Sometimes that can upset things for a while.
Good luck
Ade
91 C4 M
I would start by looking at the battery and ensure that it has enough cranking charge.
Try recharging it overnight and giving it another go. Is it the correct battery.
Is the engine in good condition? compression etc. Has this prob. just started.
Has the oil been overfilled recently. Sometimes that can upset things for a while.
Good luck
Ade
91 C4 M
09-05-2001, 04:33 AM
#3
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There are a zillion potential causes of this problem. The most obvious has been mentioned.
Battery. When you are cranking have somebody check the voltage of the battery. Should be greater than 9.5VDC at the very bottom of the tolerance.
If the battery is okay,
Check the belt drive on the secondary distributor.
The most common component failure at cold start is the Engine Temp Sensor. It is mounted on the engine. It is not supposed to be grounded. I have know people who short them out. This tells the DME that the engine temp is about 300 degrees.
If the sensor which is a Negative Temperature Coefficient (NTC) has failed at a low resistance it is actually causing the DME to feed too much fuel.
Another common problem is the much mentioned DME/Fuel Pump relay R41. These relays are somewhat unpredictable in their operation when they fail.
The fuel pump itselfs of course. When cold it may not be up to operating speed.
Can you hear the pump running. It should crank up the instant (within one second) of turning the ignition on. Just wait, do not start, leave the ignition on and listen for the fuel pump.
I would check the obvious first and then look for the more complicated.
Ciao,
Adrian
911C4
Battery. When you are cranking have somebody check the voltage of the battery. Should be greater than 9.5VDC at the very bottom of the tolerance.
If the battery is okay,
Check the belt drive on the secondary distributor.
The most common component failure at cold start is the Engine Temp Sensor. It is mounted on the engine. It is not supposed to be grounded. I have know people who short them out. This tells the DME that the engine temp is about 300 degrees.
If the sensor which is a Negative Temperature Coefficient (NTC) has failed at a low resistance it is actually causing the DME to feed too much fuel.
Another common problem is the much mentioned DME/Fuel Pump relay R41. These relays are somewhat unpredictable in their operation when they fail.
The fuel pump itselfs of course. When cold it may not be up to operating speed.
Can you hear the pump running. It should crank up the instant (within one second) of turning the ignition on. Just wait, do not start, leave the ignition on and listen for the fuel pump.
I would check the obvious first and then look for the more complicated.
Ciao,
Adrian
911C4