Im posting this up for my buddy he has a 01 ram 1500 5.2 somewhere around 135k on engine mods are K&N intake,Jet stage 2 chip and exhaust chopped off at cat. This problem has gotten much worse. Just did plugs,cap and rotor last weekend wires are only have couple thousand on them. Anyways when the truck is cold you can either be driving it or just let it idle and it will start to miss and the rpms will go up and down almost like someone is tapping the gas. Its really bad if its just idling it sounds like it has a crazy cam in it. When it does it you can hear it really sucking for air and can smell unburnt fuel. I've drove it couple times when it does miss. Its when you get on the gas it will do nothing and kinda want to die out so you have to let off and it will come back to life and it will be fine. Now its to the point where he said it is starting to miss while driving under normal conditions like if its in a high gear it will buck. Also its not throwing any codes. I've got a code reader and im going to put it on this weekend see if anything is unusual. Any ideas guys. I thought maybe injector but its got to be missing on more than one cylinder what about crank sensor? or maybe pcm going? Just what stumps me is normally only does it when its cold. Any help is appreciated!! Btw if you guys want a vid let me know and ill get one.

 

Might be any number of things. Bad plenum gasket. Failing IAC motor. Bad TPS, or crank sensor, or cam sensor, or even the O2 sensor. (none of which will set a code.) Might be as simple as plug wire routing. (there is a technical service bulletin in the FAQ section here, that shows proper routing to 'fix' a misfire situation. Probably should start there, and see what happens.

 

Well can rule out plenum gasket cause it was just done.

 

Did the manifold bolts get replaced? (they are not re-usable.) Might have a vacuum leak somewhere. Might want to explore that as well.

 

Really? well we never replaced them is there any reason why you have to replace them?

 

Those intake manifold bolts are torque-to-yield so are stretched the first time and worthless the second time. NEVER reuse TTY bolts.

Replace those because it needs doing anyway, and see what happens. It might not fix the problem he's got now, but if not it'll prevent the one that's on its way.

 

That right! NEVER reuse torque-to-yield bolts. First, change the bolts out cause you probably have a vaccum leak...thats a good start. No codes sucks...makes it harder to hunt down the prob....What spark plugs did yall put in? The next cheapest things to change out would be the IAC and TPS sensors off the throttle body..about 30 a piece right there...MAKE 100% sure the wires are routed correctly!

Report back and let us know an update...

 

First thing! Remove the POS Jet chip and put the motor back to stock tuning.. And second, is the precat o2 sensor installed.

 

Ok ill tell him and also checked the IAC as long as it moves its good right? and I think tps is ok have to check it with a meter and find out. He did re route the wires also. When he gets new bolts will he need another gasket or will it be fine?

Yes i've told him many of times to get rid of it I heard the computer goes back to stock tune after so long anyway so its prob useless now. Both o2's are installed.

 

Thought I would give you guys a update. We got new intake bolts and redid all the gaskets so basically we did the job 2 times lol anyway while he was getting another tube of rtv I was looking under the hood and low and behold I found part of our problem. I noticed the the distributer was loose on the one side causing part of the cap to lift up about 1/8 of a in so I tightened it down and the miss while driving went away but still has the weird idle missfire during cold starts. We still cant figure out whats wrong IAC and tps are good. Ill get a vid this weekend so you know what we are dealing with.