Hi its a 1996 2500 V10. I have been trying to fgure out why I have rough idle and the engine bogs down occasionally. The idle is only rough sometimes, and by rough I mean the tach bounces up and down slightly and makes the truck shudder and sputter. The bogging happens when I am accelerating. Basically what happens is that I press the gas pedal down and the rpms will go down without the pedal moving and there is a huge loss of power, and then all of a sudden it will jump back up really hard. Sometimes it will do it over and over again,and sometimes only once. I have recently replaced my fuel pump, but that didnt fix anything. I have noticed that it bogs and idles rough specifically when I am up in the mountains driving on rock roads and when it is raining. That made me think it is the IAC because it could get some moistuure or dust on it and make it stick. I was wondering if there is aother sensor that could cause this same problem like the TPS or something else. Any clues would be appreciated, and does anyone know what kind of bolts and what size are holding the IAC on? I can't see the back and I want to take it off to see if it is filthy. Thanks! Oh yeah, I also have a really strong exhaust smell like its really rich. If I let the truck idle it begins to smell really strong like not fully burned gas, maybe thats just because this engine is really inefficient....

 

o2,,,maybe and also the iac

 

The o2 could be affected by rain and dust?

 

huge loss of power....plenum gasket?

and yes o2 sensor before CAT

 

Ok, I just drove it to the store, and it did the bogging thing. The tach doesnt move down, the power just goes away and comes back and then goes away and comes back again like something is loose and half of the cylinders are turning off and coming back on. The rpms don't change though....weird. It started this afternoon when I hit some puddles pretty hard, probably got a sensor wet, or maybe even the spark plugs. Ill see what it does tomorrow its supposed to dry up here in georgia.

 

The best way I can describe the bogging is that it feels like the engine is being deprived of either air or fuel by some sort of valve that is sticking or opening and closing when it shouldn't..... without changing the rpm....

 

sounds like the plenum gasket....look down into the throttle body and see if theres any oil

or could be the cat, bang on t with a hammer and see if you can hear the honeycomb movin around...obviously dont hit it to hard, dont want to break the honeycomb

 

Ok, I have looked in the throttle body before and there wasnt any oil, but ill check it again. I am going to remove the cat, I bought a y pipe I just havent taken it to the shop to have them install it yet. The o2 sensor that youwere talking about, is that the downstream or upstream? The plenum thing will cause the engine to only run like crap sometimes? Most of the time it's ok. Ill check it out tomorrow when I can see. Thanks for the help.

 

well i dont think to V10 has a Plenum gasket not

a bad cat could be right

and the post cat o2

 

Yeah I just did a search about a v10 plenum and it doesnt have that problem. I guess I will mess with the cat, I just don't know what to look for. Should it sound hollow?