Surging engine, to tachometer, no power - TCCoA Forums
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post #1 of 3 (permalink) Old 06-11-2014, 06:45 PM Thread Starter
Join Date: Jun 2010
Location: DuPont
Posts: 5
Question Surging engine, to tachometer, no power

This is probably been addressed before, but here I go;
This has been a recurring problem with my 90 SC, start up and start driving, depending on speed (surface streets), engine warms up gradually, there are no issues. However if start up and immediately get on freeway within 5 to 7 miles engine runs rough, tach stops reading (drops to 0), engine still running, jerky (will rev) but without any serious muscle (note oil pressure steady), usually within the next 1-1.5 miles tach pops back on, serious power back, can continue to drive for next 200 miles no worries.
What is going on??

What module controls the tach? ICM? This is frustrating, I hate to just throw parts at something. Help!
John Cohen is offline  
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post #2 of 3 (permalink) Old 06-12-2014, 07:16 AM
T6Rocket's Avatar
Join Date: Nov 2004
Location: Raleigh, NC
Posts: 1,761
May be the crankshaft position sensor. Is it ever hard to start, like cranks over and over?

When I had a bad one on a 4.6, it would crank over and over and the tach would read 0 instead of 200 RPM while cranking. Then other times it started right up.


97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
04 CVPI- Brenda's car - 76k miles
Previous Fords:
95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles
T6Rocket is offline  
post #3 of 3 (permalink) Old 06-12-2014, 02:36 PM Thread Starter
Join Date: Jun 2010
Location: DuPont
Posts: 5
nope, always starts within seconds, this has only happened while driving, and so far only while warming up. Is the crank sensor where the signal comes from for the Tachometer?
John Cohen is offline  

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