The more I accelerate, the less power I have

[Chris Estes]

It all started when my 2006 TJ started acting like it had a rev-limiter at around 3200-3500 rpm. I had a code that said my cam/crank was miss aligned, I drove it like that for a while, then it started acting like it wasn’t getting enough fuel the more I pressed the accelerator. It idled fine and ran ok just easing on the pedal but when I pressed down it sounded like it’s sucking air. The harder I press the worse it is. I changed the cam sensor first, then I changed the OPD assembly. Still have the problem with no code.
I tested the fuel pressure just turning it on and also running and it’s good. Does anyone have any tips on what to do next?
Please help!!

 

[TJ Jim]

tested the fuel pressure just turning it on and also running and it’s good

Welcome to the forum. What is the pounds of pressure? Good is relative.

 

[JMT]

Have you checked your throttle body to make sure it’s opening and clean?

 

[freedom_in_4low]

Sounds like classic fuel starvation. Just because it has fuel pressure at idle doesn't mean it will with revs and throttle. I would rig up the pressure gauge where I can see it from the driver seat and go for a ride before throwing any more parts at it.

 

[GoldenGorilla]

If you are still having a check engine light, the 2005/2006 models have a limp mode that limits them to I believe 2800rpm.

If your OPDA or crank position sensor is going bad, you might be hitting that rev limiter.

If you can get a OBDII bluetooth reader on it and the use an app like Torque to scan the O2 B1S1 and B2S1 voltage up to and at those rpms it can provide more info

 

[TJuser]

It all started when my 2006 TJ started acting like it had a rev-limiter at around 3200-3500 rpm. I had a code that said my cam/crank was miss aligned, I drove it like that for a while, then it started acting like it wasn’t getting enough fuel the more I pressed the accelerator. It idled fine and ran ok just easing on the pedal but when I pressed down it sounded like it’s sucking air. The harder I press the worse it is. I changed the cam sensor first, then I changed the OPD assembly. Still have the problem with no code.
I tested the fuel pressure just turning it on and also running and it’s good. Does anyone have any tips on what to do next?
Please help!!

How's the catalytic converters? Mine would hit 3500 rpm tops, but idled fine when they were clogged. Sometimes it'd have power, sometimes it wouldnt.

 

[CharlesHS]

IF all else fails... as TJuser posted above; the catalytic converter(s) may be getting plugged which will limit engine power.
The harder you try to accelerate the more the engine power loss is felt.
You can have the incoming and outgoing temperatures of the catalytic converters(s) tested.
You can take your Jeep to a shop where they will test exhaust pressure before and after the catalytic converter(s) looking for pressure drop.

 

[JKP]

Weak fuel pump, weak coil, or plugged cats.

Check the fuel pressure while revving the engine.

Unlikely all 3 coils in the rail are going bad, but you may be losing 2 cylinders if one is going bad.

 

[macleanflood]

Could it be a misaligned OPDA causing the PCM to go into limp mode?

-Mac

 

[Strizzo]

manual or automatic? when i was getting the cam sensor code, it went into limp mode, which would limit rpms to right about where it would be if you were trying to pull out into traffic quickly, and then it would fall on its face. it would drive fine otherwise below 2800-3000 rpm.

 

[TJ Jim]

@Chris Estes must have solved his problem or given up. One post and ghost

 

[Chris Estes]

Sorry everyone for not replying back or posting an update! I got the problem solved. A friend who is a great mechanic, and who was helying me with this when he had time, told me it had to be a fuel problem or a catalytic converter problem. Since we had checked the fuel pump and everything seemed fine, I bought a exhaust pressure tester and checked it at the sensor in front ofthe converter closest to the rear of the exhaust. It was stopped up. That was the problem with no power, not the rev limiter problem. So I reset the timing and everything is working great. Thanks for all of your advice!
Sorry for not posting sooner but I actually just got this fixed last weekend!

 

[Chris Estes]

@Chris Estes must have solved his problem or given up. One post and ghost

I did! Sorry for not responding sooner!

 

[TJ Jim]

I did! Sorry for not responding sooner!

Awesome!! Thanks for coming back and sharing your experience with us!!!! Glad you fixed it

 

[Zorba]

...I bought a exhaust pressure tester and checked it at the sensor in front of the converter closest to the rear of the exhaust. It was stopped up. That was the problem with no power, not the rev limiter problem. So I reset the timing and everything is working great. Thanks for all of your advice!
Sorry for not posting sooner but I actually just got this fixed last weekend!

I just checked into this thread - that was exactly what my '06 had going on, a clogged rear cat. I have an in-cab vacuum gauge, vacuum would drop to about 5, and no power at all! Engine got hot, but cooled right off at idle. No codes.

 

[dbbd1]

I just checked into this thread - that was exactly what my '06 had going on, a clogged rear cat. I have an in-cab vacuum gauge, vacuum would drop to about 5, and no power at all! Engine got hot, but cooled right off at idle. No codes.

We did you tee into your vacuum line for your gauge?

 

[Zorba]

We did you tee into your vacuum line for your gauge?

About a foot or 18 inches from where it connects to the manifold.

 

[freedom_in_4low]

interesting. I recently noticed our 4runner seems down on power (2010, 235k miles, no CEL) and on fuel economy as well. it doesn't fall on it's face like a fuel issue, it just seems to require more throttle (and sometimes all of it) to get to the power levels I need to pass, or accelerate at highway speed. I'm going to do an exhaust backpressure test when I get back next week, and I may just replace the O2 sensors while I'm at it, since I have to take them out to do the test anyway.

Some googling suggested the exhaust pressure upstream of the cat should be less than 1.5psi with 2500+ rpm and 3 psi would indicate severe clogging. Do those numbers check out?

Really crossing my fingers that it's just lazy, ancient O2 sensors as I really am not looking forward to a cat replacement on that thing. The first pair are part of the manifold assembly and they're not cheap.