Dear Forum Members,
I've posted a couple questions about this particular truck already.
We have a 1993 Ford F-350 Crew Cab Long Bed 4X4 with the 5.8 Windsor.
Recently the trans modulator failed (C6 3 Spd Auto) and the truck ingested transmission fluid into the intake.
After this the truck ran extremely weakly. We repaired the original issue by removing the catalytic converters, bypassing the vacuum pump, changing the plugs, and cleaning the ACT sensor and the truck still ran extremely weak and would not accelerate even after shifting down with high throttle. The truck runs better at lower throttle but the power comes in little jerks and it still runs poorly. The fuel pressure KOEO was only 30 PSI and KOER with 32 at idle, 25 with a load, and 32 with the regulator unhooked! I changed both pumps as the pressure was only slightly different between front and rear, replaced the FPR, and the fuel filter. Now the pressure is up to where it supposed to be (I don't remember exact readings) The ACT was nasty and failed a resistance check so it has also been replaced. The only code we have is 172 (Lambda Sensor Right Too Lean)
I do not have the tools to check the MAP unfortunately. The timing is spot on (10Deg with Spout Disconnected)
Does anyone have any thoughts?
As I said the power is reasonable but still weakish at low RPM (up to 2500ish RPM) and it comes in little bursts with steady throttle. The engine might occasionally miss but certainly not badly enough for me to notice without focusing on it.
Please let me know!
I feel like a failure of a mechanic but this is how we learn!
-Mahoney
The parts used are quality, mostly Carter, Ford, NGK, and Standard Motor Products.

 

I'd suggest you change that O2 sensor. The MAP could also be contributing but if the cats were clogged good chance the O2 is also dead.

 

Conanski,
Good suggestion! Are there any O2 sensor tests I could try? I know its not testable with a mulitmeter.

 

I have ran the truck with the o2 disconnected to see if keeping the system in open loop helped. It really didn't help much. I have cleared the codes since then and retested.
-Mahoney