Cool engine stutter

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4babycar

Cool engine stutter

Post by 4babycar »

My recent issues with my 80 have renewed my efforts on my 82. I have managed to fix the oil leaks and coolant leaks but I have one nagging issue left to solve, at least for the moment. Once the car starts it runs and the idle is smooth but maybe a bit low. It will keep this idle as long as you stay off the throttle. If you attempt to rev the engine it will stutter and bog down. Let off the accelerator and a second or two later, it will level back out. Once the car warms up, the stutter goes away and it runs and revs smooth. I disconnected the AAR and it revs high for a second and dies. I know I have a failed vacuum advance but after blocking off the vacuum line, the issue still remains.

HELP!
So Cal Mark

Re: Cool engine stutter

Post by So Cal Mark »

what's the air/fuel ratio at that temp? Are the injectors clean?
JohnnyRaggs

Re: Cool engine stutter

Post by JohnnyRaggs »

I don't know much about the spider fuel injection systems, but I have seen this issue before on newer vehicles. They usually end up being the MAF (mass air flow sensor). I would check the air flow sensor, make sure that its working normally.
4babycar

Re: Cool engine stutter

Post by 4babycar »

Mark - I do not know what the Fuel/Air mixture is, how do I measure it? The injectors were cleaned and tested (although, just verifying they open and close) before installation.

I have checked that the AFM is clean and the door moves freely and since it runs well after getting warm, I don't believe that it is that.

I also failed to mention that I removed the AAR and at the ambient temperature of ~75F it is almost completely closed. I blew through it and only a trace amount of air was able to pass, either direction.
ClarkTheShark

Re: Cool engine stutter

Post by ClarkTheShark »

hmm could be a temperature sensor. i would try and ground the coolant sensor wire to the motor on start up.

also the L-jet system has a thermo-time switch under the intake manifold. this turns on and off the cold-start valve. an easy way to see if your cold start valve is working- place your hand directly on the top of the plenum. if it gets really cold during start-up then the valve is working.
4babycar

Re: Cool engine stutter

Post by 4babycar »

The cold start valve is working. I grounded the coolant sensor and no change. What next?
4babycar

Re: Cool engine stutter

Post by 4babycar »

Tonight I found out that if I disconnect the coolant temp sensor in the coolant T it runs and accelerates great. Does this indicate another problem or do I just have a faulty coolant sensor?
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