Hello-

Late DME/AFM in an early car. Stock DME/AFM some 180 miles away.

Took DME out to put stock chip in for smog test. Now, car won't start. Put other chip back in. Still, no start. Swapped fresh DME relay. Same.

Some symptoms:

Bouncy needle
Almost turns over/cuts out/surging when just switched on
hear fuel pump
sporadic spark

Newer motor sensors
Static(ie) day.

Thanks.

Michael

 

Check the orientation of the chip you put in, make sure notch on chip lines up with notch on socket or notch print on board.

Also, it's possible that flexing on the DME plug could have broken loose a solder connection, inspect the boards carefully for cracks in the solder connections to the plug pins, and also on the plug itself make sure one or more contacts isn't sunken more than the rest and all are clean.

Regards,
Russell

 

Thanks Russell.

Chip is oriented correctly but I will take your suggestion and examine the contacts and plug carefully.

 

How confident are you in the speed and refrence sensor connectons on the back of the engine?

If the refrence sensor signal isn't there, you'll still see the tach bounce, you'll get a spark and fuel, but the timing will be off. Try holding the throttle wide open while cranking, if it starts and runs poorly, keep on the throttle; see how it runs around 3-4k rpm. If it goes from running like crap to almost normal with a bit of speed, it's the refrence sensor.

There's very little you can do to a DME to break it, short of something really stupid like reversing the polarity or physically breaking something. I suppose if you're swapping chips it may be possible to jostle a marginal connection, but chances are it's something else...

 

Thanks. I will try that in the morning light.