weird mustang acceleration

Mustang5oh

Mustang5oh

Forum Member
So, my mustang is a mostly stock 91 hatch with a 5 speed. From what I was told when I bought it, it was a stock rebuild. It has the usual, exhaust, pulleys, cold air, etc. Heads, cam, intake are all stock. Also the smog crap was all removed. Here is the problem. When accelerating at about half throttle, when it hits about 3000 rpms it feels almost like an extra boost of acceleration. It is very noticable in 2nd 3rd and 4th gear. Also not all the time, but more so than not, it falls flat on its face at 4600 rpms and other times it will pull to the normal 5100-5200 rpms. Does anyone have a clue what could be causing this. any help would be appreciated.
 
Fuel pump or ignition drop out. Rarely it could be a vlavetrian issue. Would not be unheard of.
 
Could be worn out valve springs. Have you checked the Base Timming and TFI module ? TFI modules burn up like candy.
 
sounds like a bad mass air to me i had one that did that thought it wasthe tps but ended up bein the mass air
 
The valve springs are on the to do list, and I'll look into the mass air. I was hoping to be replacing it with something better not to far in the future.
 
Sean said:
Are you getting a check engine light ? If so what codes ?
Click to expand...

Check engine light comes on for a few minutes every other week and then goes off again. I do need to see what codes are coming up though. Thanks for all the suggestions. I'll give em a try this week and report back...
 
my8950 said:
I would check the timing, and also make sure the distributor is tight when you're done. By the way you describe, its not repeatable 100% of the time. Also, I would think that its not TFI, usually when that fails, they usually fail from heat, so once they get hot and run a bit, then will crap out, stall and cool down, starts back up until heated again, and so on...
Click to expand...


I checked the timing and it is at 13 degrees.

How do you check the mass air sensor?

I have had a TFI go bad before and the car barley ran because of it. The car seems to run fine, then it acts up on just acceleration...

2 scenariors: 1. under partial acceleration for the extra added "boost" at 3,000 rpms
2. full throttle fall off at 4600 rpms
 
You must log in or register to reply here.
Back
Top