Hey, I,m new to this site but am in need of some help. I recently purchashed a 2wd 96 f-350 with a 5spd, 370,000 miles on truck 200,000 on motor. I have replaced the batteries, cables, valve cover gaskets and wiring on both sides, fuel pressure shim and gauge, changed all filters and fluids. Now the truck is running much better up until 2100 rpm where it starts missing, I unplugged the MAP sensor and the truck runs WAY better, the turbo actually works! Bought a new MAP plugged it in and now we are back to running like crap again! Check engine light has only ever came on once, and that was when the MAP was unplugged, fuel pressure is running 50psi. I am at a loss here, obviosly the MAP is gettin a bad reading but im not sure what to do next, any help would be greatly appreciated, thanks.

 

If you unplug the new map sensor, does it run great again?

What do you mean by "the turbo actually works"?

The only thing I can think of is to check the square cut O-ring at the exit of the turbo.

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Maybe check anywhere boost can leak and check the compressor wheel for "dusting".

 

Yes, it runs better when I unplug it again, it seems like with the MAP hooked up its starving for fuel which in turn isn't spooling the turbo as it should, I'm getting much more reaction out of the turbo with the MAP disconnected . I am just at
a loss for ideas. Thanks I will check that o-ring tomorrow

 

Is it blowing any white or blue smoke?

 

Yeah, white

 

When and how bad? it sounds like a fueling issue, the motor is getting to much fuel. If its only doing it at higher rpms i would think it might be a cracked injector nozzle

 

Smokes all the time, if anything more at idle, hard for me to tell under load,I cant see tailpipe. Is there any way to make sure its an injector before pulling? Also, I'm assuming with the miles on the truck, if I have to replace one injector I "should" replace all of them ?

 

It could be injectors, it really sounds like a cracked nozzle, you have to be very careful though because that broken nozzel can turn into a cutting torch and cause MAJOR engine damage. How does the truck start in the morning? does it sound like it has a miss? The only way your gonna tell which ones are bad is too have them tested on a flow bench. And i would change all the injectors. I have ran injectors to 300k miles and the truck ran very poorly and would smoke blue and white really bad on cold starts.

 

O boy, pulled valve cover,injector 7 isn't pumping oil but 5 is!

 

the injector is bad, replace it. How are all the other ones? are they pumping oil?