92 5.0 rough idle issue

[5.0Flareside]

Ok guys. running into an issue with the Flareside.

I've been through 3 TPS's. Each time they've tested bad after some miles. now i have a new one on and it tests good.

New(used) MAP sensor as well.

The truck will have hard startups and will smoke real bad at first when finally get running.

when i get the truck running it'll run ok for a few miles and then start bucking extremely bad and die at times. confused.

Constant Power from the MSD coil. New plugs. Checked the Fuel pressure a few weeks back. checked out fine within specs.


I'm lost on this issue.

HELP!!

 

[SuperCab]

What color smoke?

Also, to go through 3 TPSs you may have a short/bad ground/etc. that made them go bad.

Do you know if your MAP sensor currently tests good?

You mentioned new plugs, but IIRC you have new wites, cap & rotor, etc? correct? so we can rile that out...

 

[5.0Flareside]

yeah wires cap rotor everything spark wise is new.

the original TPS went bad before i got truck. replaced it.. the one i replaced it with was bad out of box.

warrantied that one out and the new one lasted 3 months and like almost 4k miles.

the MAP sensor is good.

the smoke is white and thick..

 

[Ridgerunner]

Did you pull the codes. I found a total of 5 codes that showed up all were emissions and fuel related.

 

[5.0Flareside]

i dont get any right now.. forgot to mention that.. i havent driven enough since reset after TPS swap..

its undrivable..

 

[Ridgerunner]

I would think you would find some codes. How do you pull your codes? I used this method and my multimeter to get my codes.

http://oldfuelinjection.com/?p=13

 

[5.0Flareside]

no i've pulled codes... i have a ford OBD-I code reader...

nothing just 11.. all systems clear..

 

[Ridgerunner]

Might not hurt to try this way too. I used a code reader too and guess what it showed no codes at all.

 

[5.0Flareside]

was able to keep it running long enough to get the codes to pop up..

(22) MAP sensor and (34) EGR valve

gonna reset computer and go from there.. havent been able to do that yet..

 

[Ridgerunner]

So you did the KOER test which is good. I did the same to back up the codes I found with the engine off.

 

[5.0Flareside]

no those are the codes i got KOEO test...

i drove the truck around enough to set off codes.

only thing i got KOER was cyl 8 balance test fail

 

[primetime]

Didn`t blow a head gasket, did you?

 

[5.0Flareside]

nope.


got it running right...

never allowed the ECU to reset after swapping out the MAP sensor..

it was going crazy and dumping tons of fuel in.. it was thinking the MAP sensor was still bad...

driven 50 miles today in it..

 

[primetime]

Sweet. Glad it`s being all it can be.

 

[5.0Flareside]

only so much a lil ole 302 can do lol... in stock form...

 

[sticky58]

A couple of things to try, check for vacum in and out of the soup can on the psger side fender well,that operates all your vacum controls,second, if plugs are fouling up with fuel,check coolant temp sensor on the manifold by thermostat,this tells the computer its 40 below and dumps fuel, hope this helps....nice truck by the way, I`ll have to post pics of mine..