99MUSTANG5.3L

The car is an 01 Mustang that I swapped in a 5.3 from an 04 Avalanche w/ a 4l60e from a 2000 Camaro Z28. I did the harness myself.

The problem is when driving the car 1st gear seems fine, but when it shifts into second it starts stumbling real bad. I tried disconnecting both O2 sensors and that made no difference. I haven't driven the car on the road yet(only in the alley) to see if once it gets out of second gear if it changes at all. When it sits in park it revs fine and souds real good ,very responsive. It has a mailorder tune on it.

On another note, will a VSS from the above mentioned truck trans(I believe it was a 4l80e) work with the 4l60e? Thanks for the help,Mark.

deuce4935

iTrader: (2)

If the Avalanche was a 5.3 then the trans was a 4l60e. Did you wire a 80e trans plug into the 5.3 harness or are you using what was already there?

99MUSTANG5.3L

No I just used the plug that was there.

deuce4935

iTrader: (2)

The vss is the same for both the 60e and 80e transmissions. AC Delco pt#24203876

pdsq98gt

What do you have done to the engine? Check your fuel trims while driving it with the o2 sensors connected. Any codes?

99MUSTANG5.3L

No, there aren't any codes. The only parameters I can check are those available through my Actron scan tool.I'll hook it up and take a ride and see what info it logs.

The engine is stock no mods, truck intake and all.

99MUSTANG5.3L

Couldn't take it for a ride today because it's been raining all day. I will as soon as the weather clears up.

pdsq98gt

Since it's all stock check your fuel

pdsq98gt

Since it's all stock check your fuel pressure. You want about 60psi. Tape a fuel pressure guage to the windshield and drive to make sure you have suffecient fuel under load. If that is ok, there may be something going on in the tune.

99MUSTANG5.3L

Yea I was thinking fuel pressure also. Gonna go hook up scan tool and take it for a ride and see what comes up on the scan.

99MUSTANG5.3L

Ok, just took it out for a drive with the scan tool hooked up and it threw a P0300 code. I have to go get a fuel pressure gage now.

99MUSTANG5.3L

Well, I picked up a fuel pressure gauge,hooked it up,and took the car for a ride. Fuel pressure drops to about 30psi and picks back up to 60psi. I had to modify the fuel "hat" that the factory pump sits in and I think its going into fuel starvation from fuel slosh. I'm gonna fill the tank and see if it happens then.

pdsq98gt

Sounds like you're onto something.

99MUSTANG5.3L

Thanks for the suggestions.

Supernaut

So everything is a go?

99MUSTANG5.3L

Yes it is!!! I just took it for a spin down the alley and it runs perfectly. Puts a smile on my face every time I hit the throttle. It looses traction so easily.