Low power on hills

[sussman00]

Hi All,

I've got an issue with my 88 2.9 I'm hoping someone can help with. The truck seems so sound fine. It idles great and doesn't seem to have a miss. However it recently started loosing power. On hills it is ridiculously weak. The gas milage has also dropped. I'm getting 10-12MPG now where I used to get 19 consistently.

At first I thought it needed just a tune up. So I put in new cap/rotor/plugs/wires. I also replaced the air filter and fuel filter. The new parts made it run better. But it didn't fix the power loss.

After reading up on this problem in past threads I have checked the following: FPR does not show any fuel in the vacuum line. I tested the fuel pressure and it looks good. Starts at 40 with the ignition on. Drops to about 33 when I start the engine. If I unplug the vacuum line to the FPR the pressure goes back up to 40.

I also checked the vacuum pressure. It holds steady at 19 which is just about right I think.

I also checked the codes. The only code coming up is 41 - lean condition during the KOER test.

The O2 sensor is not that old...so I am hesitant to replace it. Is there anything else I can try to diagnose the problem? Any thoughts on what might be causing this?

Thanks for your help.

 

[IMenriched]

Hi All,

I've got an issue with my 88 2.9 I'm hoping someone can help with. The truck seems so sound fine. It idles great and doesn't seem to have a miss. However it recently started loosing power. On hills it is ridiculously weak. The gas milage has also dropped. I'm getting 10-12MPG now where I used to get 19 consistently.

At first I thought it needed just a tune up. So I put in new cap/rotor/plugs/wires. I also replaced the air filter and fuel filter. The new parts made it run better. But it didn't fix the power loss.

After reading up on this problem in past threads I have checked the following: FPR does not show any fuel in the vacuum line. I tested the fuel pressure and it looks good. Starts at 40 with the ignition on. Drops to about 33 when I start the engine. If I unplug the vacuum line to the FPR the pressure goes back up to 40.

I also checked the vacuum pressure. It holds steady at 19 which is just about right I think.

I also checked the codes. The only code coming up is 41 - lean condition during the KOER test.

The O2 sensor is not that old...so I am hesitant to replace it. Is there anything else I can try to diagnose the problem? Any thoughts on what might be causing this?

Thanks for your help.

Checking Compression would be something to check....hopfully you're not week on a cylinder or two.
the other thing is to do is go over all your grounds and connections.

as far as O2 sensor goes....make sure the wires are good to it. Sometimes they get too close to the exhaust. & yeah....maybe it could be faulty.
http://www.therangerstation.com/tech_library/O2Sensors.htm

Presume that the fuel and air filters are resent as well?

 

[DisturbedMXer8]

I'm pretty sure that certain exhaust restrictions can have an effect when going up hills. I don't remember the exact circumstance, but I remember reading about it at school. Take a look into that if you haven't already.

 

[copperminer2002]

compression check. Mine is doing the same thing and the compression is pretty low. Won't be long til I have to rering it. Got it out right now, but don't have the money and need to drive it. lol

 

[sussman00]

Thanks everyone for your thoughts. I have had some time to do some additional checking. The tests I have done and the new parts have not seemed to have any effect on the amount of gas the truck is using, or its low power. Here is what I have done so far:

I checked the timing at it was right on.
Both the fuel and air filters were replaced.
I did a compression test and all cylinders are between 160 and 175.
I put in a new O2 sensor and there was no change.
Run a few containers of fuel injector cleaner through the system

The only issue I have found is that there is an exhaust exhaust leak at both manifolds, but worse on the passenger side. Could that be causing the truck to run rich and reduce the power?

 

[low_five]

clogged cat

 

[Big Jim M]

The answer is

Thanks everyone for your thoughts. I have had some time to do some additional checking. The tests I have done and the new parts have not seemed to have any effect on the amount of gas the truck is using, or its low power. Here is what I have done so far:

I checked the timing at it was right on.
Both the fuel and air filters were replaced.
I did a compression test and all cylinders are between 160 and 175.
I put in a new O2 sensor and there was no change.
Run a few containers of fuel injector cleaner through the system

The only issue I have found is that there is an exhaust exhaust leak at both manifolds, but worse on the passenger side. Could that be causing the truck to run rich and reduce the power?

YES! If the air leak is before the oxy's then they are seeing a lean mixture and reporting it to the computer.. which then enrichens the mixture to compensate for the air leak.

But! Hear this! A exhaust manifold leak allows noise which you hear on the exhaust strokes... BUT what you don't hear is the air that goes into the system when the exhaust valve is still closeing and the intake is opening.. The downstroke of the piston pulls fresh air into the exhaust valve and it does huge damage to the valve, the valve seat and the piston.. Exhaust manifold leaks should NOT be ignored.
Big JIm

 

[sussman00]

Thank you for the info. I'll get the exhaust leaks fixed and check the cats. Hopefully that will fix the problem.

 

[junkfixr]

newbie reply ... but ...

just went thru the same problem... loss of power climbing hills, fuel economy dropped from 18 down to 8 - 10 mpgs. Went thru sensors, wires, tune up... vacuum test & new intake gaskets....Checked the Cats & installed new muffler , then swapped computer and believe me this truck- -

Drove me nuts ! (without using a fuel pressure guage) but I finally ordered a $25 fuel pressure regulator from Autozone and it changed every characteristic of the truck.

FIRST I did a compression check to make sure I had no cracked heads or head gasket issues THEN decided on the regulator. Idles better, cold starts, warm starts....power & acceleration improved but .... if I had it all to do again...

I would locate a fuel pressure guage or take it to the local Autozone who will pull codes & test fuel pressure. Hope this helps 'cause without this forum I would have never figgered it out. I don't think it was returning the excess pressure back to the tank. My return line to the tank was not blocked so I replaced the regulator (which had none of the problematic symptoms described) and it did WONDERS for my truck.

I'm sure some of the Gurus will snub my opinion.. but it was a cheap,easy fix in a time of desperation. Here's the route I finally took ...1. Compression .2.Clogged exhaust 3. Fuel pressure and 4. Grounds & electical connections. Thanks Ranger Station for teaching me some of the basics ! ! ! Luv my 2.9 now ! Was just lurking and searching advice on fixing the dents I kicked in it . . .

 

[powerranger262]

Where is your regulator located? I think mine(4.0L) is in the tank.

 

[sussman00]

Low_five was correct. After all that troubleshooting the problem was a cloggeg cat. The exhaust leak was a symptom of the clog. After replacing the power is back it's performing like the truck it used to be.

It was the rear cat that was clogged. I had that one replaced 50K miles ago. I would expect the part to last longer than that.

Thanks to all on this forum. I have learned a great deal just looking through the archives here.

 

[177CIOfPureLove]

Thanks, I am having the same problem, I went about it the same way but was hesitant to clear out or replace the cats. I guess I will have to bite the bullet and spend the money lol. From what I can see the cat furthest downstream is melted and clogged, but has a hole punched through it. Can't see the first one, sure its crap as well.