4.6 2V - not making power

Booboo

Member
Joined
Jan 30, 2022
Messages
106
Reaction score
16
I have been struggling with this problem for a long time and need to get it figured out. Hoping someone here will have an idea.

I have a 1997 NPI short block that I put PI heads on out of a 2001 Mustang. I had a local machine shop rebuilt he heads with +1mm stainless valves, new seals, bronze guides, new OEM lash adjusters, new ford performance followers, BTR springs and XE262AH cams.

When we were tuning it, it was down on power, the tuner estimated it was making about 160hp at 3000 rpm, buy the amount of airflow.

I have done the following since, sent the heads to another machine shop to check them out, installed a new MAF and computer, checked fuel pressure, double check the degree of the cams, swapped out the injectors, put a test light on each injector and spark plug to make sure they were firing. Put in a known good x-pipe and disconnected the mufflers (to make sure there wasn't a clogged exhaust). Installed a set of stock PI cams and removed the XE262AH cams. Compression tests have been good.

We put a tune in it from a similar car with a similar setup so it should be close but it is running 30%+ rich. Its like the air is going into the engine but not making power. It's like the air is bleeding off somewhere. Possibly out the exhaust? Is it possible to have two machine shops mess up the heads? Could they have the valves installed wrong or possible the wrong valves (too long, or short)??? Any ideas?
 

07GtS197

Well-Known Member
Joined
Mar 16, 2015
Messages
3,361
Reaction score
2,040
Location
Fort Myers, Fl
Did your tuner ever get power numbers? I would take my car and go elsewhere. A good tuner would’ve at least been able to help you zero in on the problem. There are too many variables to say for certain but I don’t think it’s the motor. How did it drive? That’s if you were able to put some miles on it.
 

Joeminnesota

New Member
Joined
Jun 24, 2023
Messages
18
Reaction score
17
I agree with both of the above comments. On my rebuild last year, the car was drivable but rough at idle and tip-in until I went to the dyno. My brand new MAF sensor was bad - right out of the box. They replaced it and tuned the car successfully. Your tuner should be able to sort that.
 

Latest posts

Forum statistics

Threads
78,343
Messages
1,525,840
Members
15,690
Latest member
happliye

Members online

Top