need Tach help
03-27-2011, 12:02 AM
#1
Instructor
Thread Starter
need Tach help
The tach on my 91 reads exceptionally high...2200 at idle
and pegs out quickly. This started to happen a few months ago.
Have no idea what to check.. All advice appreciated...Thanks
Chris
and pegs out quickly. This started to happen a few months ago.
Have no idea what to check.. All advice appreciated...Thanks
Chris
03-27-2011, 02:12 AM
#2
Safety Car
so are you saying the actual rpm is high or just the tach reading.
anyhow, I had a vacuum leak issue when I got mine. would flash to 2000+ rpm when you started it rather than the 1400-1500 it normally does. I had the big hose under the plenum pop out of the purge solenoid along with a little too much PCV valve air contributing to a high idle.
what I did for diagnosis was to take a stiff box and block off the trottle body while it idled. If it doesn't nearly stall, theres a vac leak in there somewhere.
anyhow, I had a vacuum leak issue when I got mine. would flash to 2000+ rpm when you started it rather than the 1400-1500 it normally does. I had the big hose under the plenum pop out of the purge solenoid along with a little too much PCV valve air contributing to a high idle.
what I did for diagnosis was to take a stiff box and block off the trottle body while it idled. If it doesn't nearly stall, theres a vac leak in there somewhere.
03-27-2011, 12:07 PM
#4
Instructor
Thread Starter
The tach reads too high....The idle is normal while tach reads between 18-2000r. When I get on it the tach passes 8000 r and hits the stop while there's still hard pull.
03-27-2011, 06:28 PM
#5
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Had the same thing happen with a 90 I had was a bad tach filter.
