I have an 89 302 AOD Bronco, when in cold loop it runs very strong. When it warms up and I assume goes to closed loop, it runs poorly and lacks power. Acceleration is poor, it does not knock more than once or twice as I accelerate. Cruising seems to surge somewhat. It seems like I have to use a lot of pedal to get little result. I changed the fuel filter this past week but it still runs like garbage. I ran a code scanner and got an idle out of spec (suprise to me) and thermactor inoperative. ???? Also 2nd gear when at operating temp seems to hang while cruising until more gas is given and then it upshifts.

 

There is so much to check. Check fuel pressure first when its acting up. If the thermactor code is 44 you could have an air switching concern . The smog pump blows air upstream and the hego see's all this air and says hey I need to add more fuel. Thats something to check. I was telling another guy about battery acid shorting to the hego harness. If your bronco is one of those years where the baterry cable and hego harness are all wrapped up together it could be an issue. Cat resrictions are possible, more so when hot and under load. Idle speed codes are pretty normal and wouldn't be an issue for your symtom. See if you still have computer timing when the truck acts up. Once in a great while I see a Module or stator cause some pretty wild concerns. Norm.

 

As soon as my friend comes home from space shuttle duty at the Cape, I will borrow his fuel pressure gauge. I had one more thought about my motor trouble. When leave a stoplight when warmed up, there is always a stumble at take off. It also will stumble when it downshifts to accelerate which makes the shift rougher. Can't wait till I put the pressure gauge on it.

 

[updated:LAST EDITED ON 27-Jun-02 AT 10:03 AM (EST)]Well I check the fuel pressure and no problems there. Had to buy a pressure guage. No big deal. So I wiggled the dist. cap, surely it would be snug. It was LOOSE! Previous owner never tightend the hold down clamp. I clocked it back where I found it, pulled the spout, and put the timing light on it. It was beyond 40 deg ATC! I marked 10 deg BTC and set the timing. Run like a raped ape now!!! Sometimes I assume it is the complicated things. I kept saying since I bought the truck, I need to check the timing. DUH

 

>The smog pump blows air upstream and the hego see's all this air and >says hey I need to add more fuel. Thats something to check.

I still don't understand this. Doesn't the air pump pump into the 2nd cat? How can it pump air upstream???????

 

 

Same thing happend to me, never checheck timing, changed a lot of stuff.

Well my mechanic says the timing was off 15% retarded, I always thought is was timing related but never checked as I thought is was computer controlled. He thinks the timing chain could be stretched, any ideas on that. I haven't drove it but he says its got tons of power now. Fuel preasure was good, volume good and cats not clogged.

93 XLT 5.8L Stock 110k miles