• Hello there guest and Welcome to Fox Body Mustangs forum, This forum is intended to be used by enthusiasts of the Fox body Ford Mustangs (1979-1993)!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Engine lack of power

Gaelite13

New Member
I have a 92 5.0 with a rebuilt original engine, the transmission was swapped from a manual to automatic, there is a lack of power to the rear wheels, the engine was built by a quality builder and says it’s the correct transmission any help would be appreciated
 

broncojunkie

Well-Known Member
Any idea what transmission it is? OEM setup would have been AOD. You shouldn't see a lack of power due to that, I wouldn't think. If someone put in a c6... that could suck up some power. Those were tough transmissions, but not very efficient.

The manual cars typically got 2.73 rear gear. The auto, 3.08. This was probably a decision made by designers based on different transmission gear ratios. A 2.73 behind an auto might cause some noticeable lackluster performance (but good mpg on the highway!). Any idea if the rear diff gear has been changed?

If you have a nice upgraded gear ratio (usually 3.55, 3.73, or 4.10) and still a noticeable lack of power, and you're running a healthy AOD, the next thing I would check is fuel pressure, ignition, and timing. Have you had a timng light on it? And has the spout connector been replaced? You'll remove the spout connector to check timing and then plug it back in.

Another problem I've seen is with the throttle cable. Make sure nothing is stretched, loose, worn, or broken. Pay close attention to the throttle linkage and make sure you're getting full sweep. Check the throttle blade and opening for anything that might be keeping it from opening completely.
 

Gaelite13

New Member
Thanks for the help, not sure what transmission is installed it’s not factory, everything on the engine is new along with fuel tank and 3:73 gears, can it be a torque converter?
 

broncojunkie

Well-Known Member
Thanks for the help, not sure what transmission is installed it’s not factory, everything on the engine is new along with fuel tank and 3:73 gears, can it be a torque converter?
Definitely possible. Did you confirm 3.73 gears? And what about timing? Any idea where it's sitting? There's just a lot of things that can affect performance. You should be able to manually shift it and find the power band. But you'll want to find out if it's an aod first. If so, you'll be doing the 1-2 shuffle.
 

347HO

Active Member
Way too vague in description.

How does it start and run at idle?

What do the plugs look like after warm up, and a few wot hits?

Are all cylinders firing? Are all 8 exhaust manifold tubes same temp when running?

Did you check for vacuum leaks?

Did you check the throttle blade(s) open fully?

What does "quality builder" mean?
That is the shop name?

...


Good luck.
 
Top