Cam 0 Posted July 27, 2009 Lo all, Have a bit of a problem here and hoping someone can help. My G60 (1991 J plate) is suffering from a misfire. She starts up fine, however when she starts to reach running temperature, its starts to misfire. Not so bad when you driving along at speed, though there is hesitancy, but you have to keep your foot on the gas when stationary otherwise she’ll stall. I’ve had her in the garage for a few days now and they have changed the Idle control valve and Fuel Temp sensors in the hope that this would cure it, but to no avail. One other thing they said was that one of the leads from the ecu is missing so they cant even get a reading to ascertain the problem. Has it fallen off the back? ANy reason why it would be removed? The garage (which is a small VAG approved place) reckon it’s a mixture issue, however they don’t really want to spend hours and hours trying different parts in the hope one might cure. I’m not that technically minded despite having driven cars for almost 15 years, so really need to pass it to someone for a check. I’m based just outside Glasgow if anyone has any thoughts at all. Cheers Cam Quote Share this post Link to post Share on other sites
Supercharged 2 Posted July 27, 2009 Hello there and welcome to the forum! When you say misfire what does it actually do? I assume they have ruled out HT leads / injector wiring etc and think it's a sensor issue as the fault occurs when hot? When they say a lead missing from the ECU.. do they mean the vacuum connection from the back of the throttle body? If this is the case and it's missing then I'm surprised it runs at all, this is absolutely critical and needs to be 100cm long exactly - worth replacing this anyway tbh to rule it out. Assume is was the Blue Coolant temp sensor they have replaced? If so, wait until the fault occurs and then plug the old sensor back into the wiring (so the engine switches back to a cold map), if it then returns to normal then you almost certainly have an issue with the Lambda / O2 sensor or the CO Potentiometer (these become the key sensors on the warm fuel map) Have you tried running it with the lambda probe unplugged? Quote Share this post Link to post Share on other sites
Rustynuts 0 Posted July 27, 2009 This does sound very like running with the vac hose to ECU either disconnected or on the wrong nipple to the throttle body. Quote Share this post Link to post Share on other sites
law262 0 Posted July 30, 2009 Is there a way to test the CO Pot? Are there set values to compare it to when the engine is cold, 50c and 80c? Quote Share this post Link to post Share on other sites
