Car loses power, tach goes off then comes on again...need assistance.

[kylereece22]

Hey all,
I am fairly sure that the crank sensor needs to be changed however I thought that I would ask here first to pick your very knowledgeable brains.
I have an 89 SHO with a 3.2 swap and I am currently experiencing some intermittent ignition/electrical problems.
Sometimes the car will lose power and idle extremely poorly and stall. The tach goes off and on again at random and the car will then run perfectly fine with no tach and then the tach will return as though nothing has happened. I cannot verify whether or no the crank sensor has been changed and based on my searches I think this is the best thing to do. Car has no codes posted.
What do you guys think? Thanks again for you help!!

Cheers.:thankyou:

 

[intimdatr]

Yup sounds like you're on the right track. Time for a 60k. While you're in there might as well do a timing belt and Cam sensor to get it all over and done with.

 

[Dirk37]

+1 for the cam sensor. I had the same symptoms and after replacing a bunch of parts it ended up being cam sensor.

 

[rubydist]

tach coming and going is a symptom of a bad cam sensor. a bad cam sensor can also cause all sorts of timing issues, with symptoms like you describe.

I would replace the cam sensor asap, and do the 60k at a convenient time.

edit: if the tach goes away completely (even for a short time), then you should have a code for the cam sensor being bad. if not, you could have a pcm problem.

 

[Dirk37]

if the tach goes away completely (even for a short time), then you should have a code for the cam sensor being bad. if not, you could have a pcm problem.

Strangely in my car I never got a code for the cam sensor being bad, I'd lose my tach about 3-5 times a day and never got a code or CEL.

 

[Storm-Chaser]

The way to differentiate between the crank/cam sensor is by how far the rpm drops.

Even very brief crank sensor issues will result in the rpm dropping to zero until it starts sending a signal again.

My experience with a bad cam sensor was the rpm would drop to half what is was before - but never to zero.