Cat plugged maybe?

[n_bannerman]

Ive got an 88 with a 2.9 in it and have been having issues with it running fine for a bit then all of a sudden the rpm's will drop and if im stoped or at an idle i have to keep my foot on the gas pretty good to keep her running, it is almost acting like I have a compression brake on but i dont have one. I am wandering if any one might think that maybe my catalytic converter is gone out and keeps getting plugged causing my truck to almost stall then backfire and leave a nice cloud of smoke. I know it is illegal to huck the cat for a strait pipe but im short on funds and am thinking of doing that to see if it will solve the backfiring and power loss issue. my other thing is, my truck is running really lean and I havent been able to figure out what would cause that, I am open to suggestion and am just trying to get my truck running as cheap as possible where I am currently out of work.

 

[mudnsnow]

If your CC is plugged your truck will never run good. An easy test is to remove a o2 in front of cat and put a pressure gage at is place. Idle you should be near 0 at 2-3000 RPM steady you should be near 0 too. Let the truck idle and do a brief WOT the pressure should rise a little but return to 0.
Hope it will help

 

[IMenriched]

Ive got an 88 with a 2.9 in it and have been having issues with it running fine for a bit then all of a sudden the rpm's will drop and if im stoped or at an idle i have to keep my foot on the gas pretty good to keep her running, it is almost acting like I have a compression brake on but i dont have one. I am wandering if any one might think that maybe my catalytic converter is gone out and keeps getting plugged causing my truck to almost stall then backfire and leave a nice cloud of smoke. I know it is illegal to huck the cat for a strait pipe but im short on funds and am thinking of doing that to see if it will solve the backfiring and power loss issue. my other thing is, my truck is running really lean and I havent been able to figure out what would cause that, I am open to suggestion and am just trying to get my truck running as cheap as possible where I am currently out of work.

Best 1st approach is to get codes. you can have codes tripped without the CEL on in the dash.

the harsh idle/running condition... is it only after it up to operating temp???
how does it run when cold?
does it runn ok going down the road??

when was the last time it was tuned up??

 

[n_bannerman]

the problems start to happen after its been running for about 10 minutes. The list of things i have done are:
replace the air intake with a cone
new spark plugs in july, pulled them today and they look horrid with only 500 miles sense being replaced
new fuel filter
new fuel pressure regulator.

when i get a chunk of cash again i will be getting new spark plugs, wires, distributor cap and rotor and having a buddy chop out my cc to see what happens.

 

[The Fox]

What do the plugs look like?

Also, it seems that it could be a bad o2 sensor as you say it is fine when the engine is cold. The computer is not doing anything but using predefined amounts and not using most of the sensors.
Nick

 

[IMenriched]

the problems start to happen after its been running for about 10 minutes. The list of things i have done are:
replace the air intake with a cone
new spark plugs in july, pulled them today and they look horrid with only 500 miles sense being replaced
new fuel filter
new fuel pressure regulator.

when i get a chunk of cash again i will be getting new spark plugs, wires, distributor cap and rotor and having a buddy chop out my cc to see what happens.

by horrid..what do you mean??? all carboned up, or burnt??? both?? shouldn't be going thru plugs that fast...something is amiss

I'd start by rechecking the grounds....and for vacuum leaks and cleaning the AIC

 

[turbo cat]

what kind of plugs were used

 

[n_bannerman]

the plugs where covered in carbon, but when i changed them this summer, the old plugs where burnt. I used some off the shelf spark plugs from the local carquest when i first changed them, but am planning on using motorcraft 42 with 8mm wires when i can get new ones.

 

[turbo cat]

brand?

 

[n_bannerman]

I cant remember the brand, I was in a hurry to get my truck running so I could drive from anacortes to wallawalla that day in it. Must have thrown the box's out with the old plugs. They were pretty cheap though, half the price as the ones I used to get for my old f150.

 

[IMenriched]

I cant remember the brand, I was in a hurry to get my truck running so I could drive from anacortes to wallawalla that day in it. Must have thrown the box's out with the old plugs. They were pretty cheap though, half the price as the ones I used to get for my old f150.

If they were not in the correct heat range...that would maybe explain the quick carboning. Certainly a good set of wires couldn't hurt. In the Tech library there is a suggstion list of tune up componets.

agreed with checking the O2 sensor.
if everything is ok spark wise and your still fouling the plugs then your over fueling.

Have you done a compression check?

 

[n_bannerman]

I havent done a compression check yet. I talked to a friend today and he told me to try checking for vacume leaks so i got a thing of starter fluid so i can check once the engine has cooled off a bit. I forgot to mention that I also replaced the valve cover gasket because I got tired of smelling burning oil as it was leaking pretty well at the valve covers when i got the truck.

 

[holyford86]

either is a bit too volatile to use for checking for vac leaks, use carb cleaner.