Bouncing Tach
 

It just startd happening. Every time the car comes to a stop the tach bounces 2 to 3 times before it settles down to a steddy idle. What could it be? Bad O2 sensor. Is the a way to check or measure? A clogged injector? Or is it something else.

John

1985 3.2 Carrera

It's not just the tach that is "bouncing" it's also the idle. The motor will vrooom vrooom a couple of time before it settle to an idle.

800 rpm on those. much higher, and they can do that. wouldn't hurt to clean the idle stabilizer valve with spray carb cleaner. B12 chemtool works good.

That's not a bouncing tach, that's a bouncing engine.

Just to clarify, because there is a bouncing tach problem which does not follow the actual revs of the engine. :)

Just to make it clear, my motor is bouncing thus the tach is bouncing also.

if it bounces when steady running, check the alternator/ voltage

I'm told a rich mixture will cause this. I have an aftermarket chip, have replaced my idle valve, and still does it. Was told it might be the chip, and that going with a Wong version w/ more memory than the 2K would likely smooth out the idle & surging.

"Idle Surge" will yield better results in a search than bouncing tach for your situation.

OK, I have observed a few things. This only happens when the card is hot. Meaning the temp needle is about half way. I goose the gas a bit at a red light and the RPM will bouce a few time, about 5 or 6 time before it settles to a normal idle. I did put some Techron the the tank, thinking it might be clogged injector. If it is running rich, what can I do to fix this?

Thanks
John

Tighten the intake manifolds.

I tighten all that I could on the intake manifold. Everything was snug to begin with. The tempp gauge is almost at the halfway point. The RPM still bouces. Any other ideas??

ALso, I check the voltage of the battery while it's running. The voltage looks steady from cold engine to hot engine. I didn't see any voltage fluctuation.