Now my truck on some days will run great no ruff idle or miss and some days it will ruff idle die at lights and shake the truck at low rpms.

I hooked up my AE while running. No codes. Icp and hpop pressure seem all to be running In good numbers. Fuel pressure is right around 60 70. Hpops full also.

Any ideas what could cause this? if the weather holds up after work im gonna take my chip out and maybe even switch idm and com. Ive got a spare set I can try. Besides that I also have a new international cps I thought about trying. But can anyone give me some places to look?

 

How about your valve cover harnesses? Make sure there are no burnt pins.

 

+1 on uvch

 

Now I had them replaced when I first got the truck 3 years ago. Unsure of the brand. When I get under the hood what should I look for in the uvch the pins themselves the wires going to injectors? Will there actually be burnt pin ends?

 

FIRST thing to do is see how it runs WITHOUT the chip.

Automatic or manual transmission? If automatic, when it does this at lights, are you in Neutral, or in Drive with your foot on the brake?

 

Automatic. When im slowing down. The rpms go below 500 and it'll rumble and buck to keep the idle. Sometimes it'll die sometimes it'll idle out or it'll die. Or a couple times I dropped it down in neutral and gave it throttle to stay running then took off ran fine.

 

The way it dies out at lights is almost like how it would act if your cps was going bad. Ive gone through that. But sometimes it won't do it at all other times it does it just idling.

 

Try dropping it into neutral, but don't hit the go-pedal. See if it holds an idle. If so, then it's _possible_ that what you're experiencing is the torque converter not unlocking sufficiently.

How old is the oil? One thing I've found is that when she gets crabby about idling, esp. dropping to idle after a high speed run, that's a sign that she's (over)due for an oil change.

 

Ill give that a try and see what happens. Oil wise I changed it in early march and it only has about 3k on it. There has been small drops on the ground after driving around a bunch but I've been pretty good with keeping it full.

 

Ok. I took my chip out and ran the truck no change. I unplugged all the wiring harnesses and looked at the prongs and the plugs. There was the front passenger side where the far right prong was melted slightly. I believe thats a glow plug socket if I remember right.

 

Are you talking about the UVCH connectors? The outermost terminals are for the glow plugs. But if a terminal is burned, it's at least somewhat likely that the corresponding terminal under the valve cover is burned, and quite possible that it has damaged the injector terminal next to it. I would pull that valve cover and check the terminals on the gasket itself, and the wiring inside.

 

Yes the pig tail side was slightly melted. Also on all of the pig tails and pins there was oil on both the connectors and around the blue like rubber part as well. With the pigtails having oil inside if it is that sign of it going bad like an ipr or icp would?

 

Yeah if you have oil getting into the connectors, then its time for some new valve covers.

 

For valve covers themselves or just the wiring harness?

 

I believe Thomas is refering to the valve cover gaskets, not the covers themselves. You will have to check the wires inside the covers for melting, when you get them off. With the melted connector, and oil there, there is a pretty good chance you found the idle problem. The IDM is sensing a short there and shutting that bank down to protect itself.