1FZ-Fe power loss (1 Viewer)

[Anvil]

I've read a few threads on this subject, but my situation is a little different. Though one thread was similar... but I didn't understand a wiring harness issue. So, I'm starting this thread, and REALLY need some help diagnosing.

I have a 1997 Fzj80 with 175K miles. Over night the engine has substantial power loss. One a road I routinely drive at 70 mph, now the rig struggles to maintain 50. The engine does not miss, and the timing is correct. There are no CEL's.

In the past year, I have replaced the following

Dizzy cap and rotor (OEM)
Fuel filter (OEM)
EGR (Denso)
All vent hoses (OEM)
MAF hose (OEM)
All coolant components (OEM)
Spark plugs and wires (NGK)
All A/C components (OEM)

I have not replaced the exhaust system, though it is next on the list.

Any help diagnosing this loss of power issue will be much appreciated! Thanks!!!

 

[Box Rocket]

Get the cats checked out. I had similar symptoms. No misfire, no CEL, injectors were clean, new fuel pump. Ended up being clogged cats.

But check your fuel pump and injectors too.

 

[Anvil]

Thanks Box Rocket! How do I test fuel pump? I ordered a MagnaFlow 23120, this morning. The y pipe needs replacing.

 

[Box Rocket]

Thanks Box Rocket! How do I test fuel pump? I ordered a MagnaFlow 23120, this morning. The y pipe needs replacing.

There are probably more accurate ways to test it than what I did, but I used my Ultragauge to check my fuel trims and could see that it was running very lean. My injectors had been cleaned not too long ago so I didn't think the injectors were the problem. I replaced the pump and the fuel trims looked good. So I might have thrown parts at it without total knowledge of the problem but a good suspicion that it was the pump. The fuel trim numbers confirm that was part of the problem.

New pump didn't cure the power loss which is what led me to check the cats. I was a bit surprised that the cats were clogged because they weren't really that old.

 

[Candy Man]

I am having similar issue of power loss when accelerating up long hills bogging sound like insufficient air flow, starving for fuel/power. may be clogged cat or muffler. Runs great all the time otherwise. Can a bad fuel filter have this effect?