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Car stumbling

Posted: Sun Feb 20, 2005 4:30 pm
by Charlie Hood
Yesterday I had to slow up for an accident on the freeway. Once I was able to speed up I stepped on the gas and the car started to stumble. Finally it caught and I was able to get to my destination. When I came out the store and got in the car the same thing happened. It was cutting out running rough, and surging. I looked at the air/fuel meter and any it was showing rich, as rich as it could show. So the car is flooding? After a couple minutes it settles down is fine until I stop it again. Every time I start the car, hot or cold it goes through this. I checked the AFM to see if it is sticking, cleaned it up and put it back. I checked and cleaned the AAV, and still have the problem. If it is the cold start system why would it do this on the freeway? (it only did once on the freeway, but then I only had to deal with one accident.) Could it be acting up and the slowing up just accentuated the condition?
'84 GTV-6 Calif.
Thanks and a tip of the hat from ole Charlie

Posted: Sun Feb 20, 2005 11:45 pm
by Michael
Hi Charlie:

One thing that occurred to me was the coolant temp sensor (there are a few of them in the collant manifold - you want to check the one which feels the LJet). An old tuning trick some guys used was to put a variable resistor inline from the output of that sensor - increasing the resistance would fool the LJet into richening up the mixture. Perhaps the sensor has failed causing the ECU to go full rich. I do know that (when I had LJet), leaving that sensor unplugged would cause the car not to start - so obviously it does a lot to determine what the mixture will be. Check the resitance when the car is cold and when its hot and see if it differs.

Best solution ... install Megasquirt/GoTech/Autronic etc :)

Cheers,

Posted: Thu Feb 24, 2005 10:25 am
by Barry
Hello Mike,Charlie-Alternatively bridge the plug(ecu goes full warm operation)and see if the problem persists.No-not the sensor,yes-possibly the sensor,but I would go with bad conductivity.These old harnesses are prone to that..

Stumbling

Posted: Sat Feb 26, 2005 4:09 pm
by Charlie Hood
Thanks for the help. Barry are you talking about shorting out the connection for the sensor that Michael mentioned? I'm confused
I checked the sensors etc. Only thing I found was that the vane in the AMF seemed to be catching a little bit. I got the wife's finger nail file in there and cleaned it up. (got it back before she noticed anything) Now it isn't doing it anymore. So I'm keeping my fingers crossed.
Thanks and a tip of the hat from ole Charlie

Posted: Mon Feb 28, 2005 9:39 pm
by Alfa GTV6 UK
I had exactly the same problems as you. It was the Bosch temp. sensor at the front of the engine that was faulty. Once replaced all problems went away.
Afa GTV6 in the UK.