bucking and farting... ***?

[jlayne]

my truck has been doing this wierd stuff for a long while now but it is starting to get a lot worse it would just do it every now and then but now it's doing it more often than not and i have decided i need to do something about it

sometimes when i take off from a stop it will pop just like a backfire and feel like it misses a beat then will drive normally untill the truck shifts.. then when the rpms drop and the motor loads up at part throttle (doesn't do it as bad if you let off the throttle or have it full bore) it will buck a few times and then drive fine untill it shifts... then it repeats

all the gauges read normal... i thought i had a fuel pressure issue but it stays between 55 and 60 psi all the time, i have tried multiple times to get codes off of it with a genisys system and with some other machines but don't get anything... it does it on all settings on my evolution and stock (although not near as bad)

any help would be appreciated... i have had the suggestion to replace the ICP sensor but they wasn't entirely confident that was the problem and neither am I... it has crossed my mind that maybe the HPOP has issues or possibly i have a injector doing something it shouldn't

 

[Swany]

A couple things come to mind. A clogged up fuel filter or bad injectors? I'm gonna assume you already checked your fuel filter so we could probably rule that one out.

 

[jharvey]

A couple of things come to mind..

1st CPS is one the way out
2nd IPR is not functioning 100%

 

[jlayne]

its been doing it to some extent over the last 3 fuel filters (20k miles) and i have been using powerservice thinking i has some nastiness in the fuel system as well, but i have pretty much ruled that out

i might have to run a cyl. cont. test on it, assuming that would tell if they are the culprit... I have seriously been wondering about the injectors myself, atleast that problem would give me a excuse to upgrade

what does a IPR act like when they call it a day?

 

[Dieselmaster]

Have you checked the harness going into the PCM and the IPR?

I had a friend who's IPR harness was loose and hos truck would do what your descibing... He used to say it seemed as though someone shut off half his engine. He tightened down the harness and hasn't had a problem since.

CPS is also a possibility... When my CPS was going out it, the truck would just die out of the blue... it seemed to happen when I was stopped or coming to a stop... but it happened one time as I was pulling through an intersection, and that's what finally made me change it. But I drove it for at least a month with it acting goofy...

 

[Dieselmaster]

Actually I was thinking of the IDM not the ICP... on my buddies truck...

 

[jlayne]

i'll check that harness DM tomorrow... i'm going to the lake for some crappie/stipped bass fishing tonight

hopefully thats it.. i really don't like the idea of spending a bunch of money right now

thanks fellas

 

[Doggy Daddy]

I think that the CPS will leave a code if it is that bad; P0340 and/or P0344. The Cyl Contribution Test (I believe) will only compare the idle quality and not tell you anything about your symptoms. If the CPS has not been replaced it could be worth doing. I heard a rumor that the International supplied ones are upgraded and the Ford supplied ones are the old spec; I can't prove it one way or the other.

 

[jlayne]

well the harness wasn't loose... figures

guess i'm going to have to through some parts at it and see what sticks... i have about decided that have a injector going bad though... when i nail it with it tuned up it surges with more smoke coming out with every surge like a injector is coming on and off... and every now and then it knocks a little at idle

sometimes i think it would be more efficient just to burn my money, although the small fire might be discouraging as well

 

[Sandman]

CPS... Mine would pause or miss or fart... every now & again.. then the cps failed.. stopped doing it with the new CPS..

 

[jlayne]

update: checked, cleaned, and put some dielectric grease on every connection under the hood i could find after it rained one day and my truck really showed its butt... it has stopped all bucking and farting... not sure which connection it was though because i did them all the same time and none of them seemed to be any worse off than the others and they really didn't look that bad, i have added greasing the electtical connections to my normal maintenance list though, i think the stuff i wash my engine with (every time i change the oil) removed the grease therefore causing a bad connection due to corrosion

 

[kwazyca]

I would still recommend keeping a spare CPS (and 10 MM wrench) in the glove box.

Hate to see anybody get stuck with a big tow bill for a 15 minute fix.

Tom

 

[jlayne]

tom,

thanks, is that the only one under there that would leave it dead in the water and not limp home/somewhere?... i guess what i'm saying is, are their other spares i need to get so i don't end up stuck on the side of the road... the truck is getting a few miles on her

 

[towcat]

This is not just for PSD's but any vehicle....spare serp belt, upper and lower hoses(just in case if the belt slices the hose in half when it takes off) couple of spare feul filters and the tools to get the job done. As far as getting greasy under the truck, if you don't want to do the job, there's always a truck mech you can call to do the job, but having the parts on hand is golden

 

[jlayne]

thanks