Power loss below 3000RPM

[Carpcommando]

1996 with Champion truck plugs and wires...175K miles

I have noticed for quite some time (several years)that my engine is some what doggy until it hits around 3000 RPM then it really cranks well with substantial power well to 4500 rpm. Kinda like when a turbocharger kicks in after a bit of turbo lag...

Also, if I floor the accelerator from a stop, the engine bogs down and runs stronger if I back off slightly to about 85-90% of full on throttle.

I changed plugs, wires, rotor, and cap with no difference in performance.

No difference between stock air cleaner and K&N replacement.

CAT was replaced 30K miles back did not seem to make any difference in performance.

Muffler is a hi flo replacement

Replace intermitant TPS...no difference on the performance.

Could it be time for injectors? I use injector cleaner every 3-4 tanks of gas.

How about the distributer? I replaced the OEM with a NAPA rebuilt one several years ago...

Any suggestions appreciated.

Mike

 

[4xBob]

You didn't mention oxygen sensor replacement- it sounds like a fuel/air mix ratio kind of problem, so I would suspect first the O2 sensor, then the MAP sensor. If you have a 1996, can you get the error codes with the three on/off cycles, then count the flashes? The error codes might help nail it down. 4xBob

 

[Eagle]

4xBob has a good suggestion. I also didn't see any reference to the CPS. A bad CPS usually shows up as an intermittent miss or a no-start, but it's possible it could be sending a weak signal to the injectors or to the ignition if it's beginning to fail.

 

[logdog]

Ditto on the o2 sensor. Also, be carefull not to use too much fuel injector cleaner, it can damage your fuel injectors.