Power Loss While Driving (2 Viewers)

[Seth_O]

1993 with no major modifications. I deleted the PAIR (10+ yo), and a couple thousand miles ago did a HG job on it. About 5yo I replaced the fuel filter with OEM. I recently replaced the radiator with all-aluminum 4 row. A couple months ago (couple hundred miles) the truck started experiencing a random power loss while driving. Seems to happen at random times, press the accelerator and no response, the RPM's drop precariously to almost dying. A few moments it will pick back up and drive normally. The issue got progressively worse until when the RPM's dipped it was not even driveable and the duration of the RPM drop got longer and longer. No CEL.

I replaced the in-tank pump and screen and that seemed to resolve the problem (inside of the tank was spotless.) Then a few weeks later it came back. I tested the TPS per FSM, and it tested good. I cant afford to throw parts at it, so hoping for some help to resolve the issue.

 

[voodu3]

1. Do you still have catalytic converters? Or are they original?
2. Have you checked if the air flow meter is working properly?
I had a similar issue I found out my cats were clogged and my afm wasn’t working properly. I had the afm refurbished and removed the cats and it runs great. I will replace the cats at some point but for now issue is resolved.

 

[ppc]

As in another thread this week, the described symptoms point to a damaged main engine wiring harness where it passes the EGR. Open up the harness and inspect wires for bare wires or other heat damage. There are several threads detailing the inspection and repair.

 

[Seth_O]

As in another thread this week, the described symptoms point to a damaged main engine wiring harness where it passes the EGR. Open up the harness and inspect wires for bare wires or other heat damage. There are several threads detailing the inspection and repair.

When I did the head several years ago I opened up the harness and then re-wrapped it with heat reflective wrap, I will check it again.

 

[Seth_O]

1. Do you still have catalytic converters? Or are they original?
2. Have you checked if the air flow meter is working properly?
I had a similar issue I found out my cats were clogged and my afm wasn’t working properly. I had the afm refurbished and removed the cats and it runs great. I will replace the cats at some point but for now issue is resolved.

CAT's are required where I live unfortunately, so I cant remove them. How did you determine your AFM wasnt working properly?

 

[efjayatee]

Shop can test for back pressure to determine if cats are clogged/clogging

 

[Batameez]

I'd pull the cats off and see how it reacts. With the amount of oil these 1FZs burn I wouldn't throw out this possibility.