Severe Power Loss/missing

[Suburban Guy]

95 Suburban, K1500, 5.7.

 

Symptoms;

Truck ran fine until I filled with gas (Bad Gas? Don't think so), fule level was really low......ran perfectly prior to filling with gas . DID NOT fill with E85 or Deisel.

 

After ~ 2 mins of driving after cold start the motor goes into like a limp mode only worse. Need to give full accelerator to move, max speed ~ 55 mph. Shifts really hard.

No ODB lights, no bad sounds but I can really feel it's missing.

Gradually, at ~ 100 degrees (1/2 warm up) it starts recovering and @~ 170 or so I get "normal" operation again. Normal acceleration with only an occasional miss. Stays that way as long as it doesn't cool all the way down.

 

Checks/repairs:

New plugs, no help (not a surprise but did them anyway).

Wires looked good, only have ~ 20k miles on them, cap and rotor anayway.

Cap had corrosion, cleaned, no help. No arcing trails, wires seated fine.

Oil level, coolant fine.

No off roading, daily pavement pounder.

Charging system normal, temp normal.

 

Possibilities are?

 

02, MAP, ECM? Stuck EGR? Fuel Pump (doesn't sound like it but??),Stuck valve (s)? Doubt it but?

 

Thoughts?

I can't let the family use the truck since I can't trust it and right now in the upper mid west we've got some single digit temps outside.

 

Thanks

[fataugie]

I would also add fuel filter to the list, but that would not address how when it warms up it gets better. Changing a fuel filter would not change based on temp.

 

Good luck

[Suburban Guy]

I will add that the (heated) 02 sensor has ~180k rounds on it and I got a 44 code last night out of the jumpered OSB (A- B) port. It's leaning towards a very expensive 02 sensor ($111 at the local dealer).

 

There was a TSB regarding putting too much oil on the aftermarket reusabale K & N airfilter and the MAF but I don't see that as an issue since it WAS running fine after a recent reclean/reoil.

 

Engine temp is normal, plugs (old ones) were nice an tan..... Fule pressure at the TBI was a steady 10 lbs..

 

Looks like the sensor went bye bye..

 

Wendell

[Suburban Guy]

So, I finally get the truck to actup while in the garage - fuel pressure is rock solid 10 lbs. Look at the pass side injector and I'm getting no spray. Unplugged them and switch injector connections and the failure follows to the other injector. Now it appears to be the PCM. I reseat the PCM and the problem promply goes away. Time for a new PCM?

Is this typical for a PCM thats gradually failing? OR, simply the need for a reseat?

 

Anyone have expereince with this?

[XLi]

So, I finally get the truck to actup while in the garage - fuel pressure is rock solid 10 lbs. Look at the pass side injector and I'm getting no spray. Unplugged them and switch injector connections and the failure follows to the other injector. Now it appears to be the PCM. I reseat the PCM and the problem promply goes away. Time for a new PCM?

Is this typical for a PCM thats gradually failing? OR, simply the need for a reseat?

 

Anyone have expereince with this?

 

I would check if you have an electronic throttle body. If so, replace it. I was told if your in limp mode this is the solution.