I have a 87 2.8mpfi.. I replaced the motor with another 2.8 because it had no compression. Then had to replace the fuel pump and filter,as the car sat for a couple years.ran ok for a week or so but didn't have a lot of power,and would cut out on me after driving for a few minutes. Then it got to the poiny where it would idle,but if i pressed the gas more than 1/4 of the way it would bog down and not accelerate and backfire.so started replacing parts 1by 1.. I have replaced the fuel pump 3 times fuelt filter,fuel pressure regulator,fuel pump relay,injectors,oil pressure sending units,distributor, rotor,cap,wires, plugs. Car will run now,but idles rough and no power. I checked the sensors and the maf sensor didn't even affect the way it ran and neither did the 4 prong sensor. Only one that affected it was the tps... could this be a faulty computer or ground problem.. running out of ideas and money at this point.. any help would be greatly appreciated,thanks

Lee

 

So I've been told by a mechanic that it could be the computer that is faulty,or a ground wire. He already checked the cat converter. And if its not the computer then it would have to be one of the sensors that aren't working right? Really need some advice

 

What makes you think it's a fuel delivery issue?

With the symptoms you describe my first thought is cat converter.

Have you tried just disconnecting the exhaust system at the manifolds/y-pipe/pre-cat and see how it runs, other than loudly? lol

There are also pressure gauges that can be used in place of the O2 sensor to see if there is a blockage in the exhaust system.

 

Ya we cut out the cat and still runs the same. Wont get out of its own way lol

 

Six beat me @ the cat converter. But if you said thats free and the ex isnt pluged then look at other things.

See what the pluges look like now, how there gapped? Color...exc

Whats the base timing set at??

What codes is it tossing if any??

Have you literly got down and smelled the exhaust?? Burn your eyes? Or is it too lean?

Hook a vaccum guage up to the intake and see what its pulling.

Check and see what the Vts of the TPS sensor is. IIRC those 2.8L are adjustable on the TB. I know a friend that had a TPI formula and the car ran crappy just from him putting on a different intake and messing with the tps. That needs to be set correctly. But someone will go into that im sure, im no 2.8L guy.

Hook a psi guage up to the fuel rail and see what its showing at idle and when you free rev it or drive it.

Theres no sense in replacing multiple parts over and over again. Its either spark, air, or fuel. If you take it those steps at a time you should find the issue. And when it comes to the ecm issues. You need to pull the codes if shes got the CES light on. Start checking things off and work at finding the problem then proving thats the problem, not just replacing parts till the problem goes away. Just my 2 cents

Just some ideas.....

 

Heres a link on TPS IAC dio.
Read up and use a VOM and and see what it says.

https://www.thirdgen.org/tpimod2