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-   -   5.0 mustang low RPM miss (http://forums.mustangworks.com/showthread.php?t=49297)

Jeff Stockham 12-30-2006 10:45 AM

5.0 mustang low RPM miss
 
I have a 1990 5.0 Mustang that has developed a high-load, low-RPM miss. The miss is most noticable at WOT below 2000 RPM and goes away with increasing RPM. My guess is that it is ignition related. I have replaced the plugs, wires, distributor cap, rotor, coil, and the TFI module with no success. It has slowly gotten worse over time.

Any suggestions would be appreciated.

Thanks,

Jeff

Mr 5 0 12-30-2006 02:32 PM

Re: 5.0 mustang low RPM miss
 
This is a tech question and should be moved to the Windsor Power forum.

Capri306 12-30-2006 06:29 PM

Re: 5.0 mustang low RPM miss
 
No problemo. :D

Mebbe you're leaning out. Is it just when the engine is at operating temperature, or all the time? Have you tested the MAF sensor?

Jeff Stockham 12-31-2006 10:48 PM

Re: 5.0 mustang low RPM miss
 
The miss appears to be independent of engine temperature. The mass airflow sensor was replaced a couple of years ago. It's the most noticable in 5th gear.

USMC302 01-08-2007 12:54 PM

Re: 5.0 mustang low RPM miss
 
Sounds like timing. What's it set at right now?

Coupe50h 01-08-2007 10:17 PM

Re: 5.0 mustang low RPM miss
 
Any mods?
If you have aftermarket rockers, adjustment could be out, you could be losing compression? just a guess.

Also, sounds ignition related, but it could be a weak fuel pump, you need to be sure your getting fuel pressure.
And that you dont have a defected coil, even if it's new.
Check engine grounds, and see if you can run a code scanner, and pull codes. could be a number of things, clean the maf, i dont care if it's new, and make sure all injectors are squirting.
good luck..

Unit 5302 01-09-2007 07:07 PM

Re: 5.0 mustang low RPM miss
 
Is it an audible misfire (backfire?) Does it clear itself out after a few pops?

Either one of those scenarios sound you could have a broken or failing fuel injector.


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