slight miss/skip at idle no codes where do i go from here?

[ScottyP5947]

Hi I am looking for some advice and some help.... I posted this in trans issues before because that's what it seemed to be at first but here goes with my issue....
I noticed it when it was really loaded down with firewood. It seemed to be hopping or pulling when I was at a stop light and rolling just off idle. It made the truck almost bounce as I was pulling away. It gets 16 mpg no matter how I drive it, it pulls hard and I would never say it lacks power. I have no codes, no check engine light, etc. Fuel and air filter changed less than 500 miles ago. Oil is right about 5000 miles on rotella 5-40. I plan to change it between now and 6000 miles and have a blackstone oil analysis done on it. My issue happens when flashed with superchips and when not, nothing seems to affect it. I keep reading about a buzz test and cyl contribution test, I don't have the means of running those right now, but I may in the future. It doesn't run bad enough to even dream that its a bad injector, but this my first stroke, but far from my first diesel troubleshooting situation <VW, mercedes, detroit, cat, cummins, gm all in my past> I keep reading about the UVC harness and how that can make for issues like this. Do I dare tear in there and check for a loose one? Do these things normally throw a code when they miss bad enough or does it take a lot? How much of a pita is it to pull the valve covers and is this where I should begin? Maybe its the hpop oil that hasn't been changed....lol. is is worth my time to get a buzz test and cyl contribution test done? How much should a shop charge me for this? Thanks. I'm going to try and put a video up of it running. Maybe that will help. - Scott

[atvquadsport]

CHeck your Exhaust Back Pressure sensor tube for blockage. Sensor is located at the top of the motor in front of the fuel filter housing screwed to a metal tube that runs to the passenger exhaust manafold. Some people clean these but they don't cost much to replace. If you clean it do take it off-you don't want to send a love chunk though the turbo.

[ScottyP5947]

I will say that I pulled the sensor just now and yup... it's clogged with soot. Are my symptoms indicative of this being clogged? I sprayed out the sensor a little and with it out, started the truck. I would have expected for something to be coming out of that hole (exhaust gas) and there was zero. Plugged up. Looks like I will be cleaning this tonight. I don't have a code for it and I don't like things plugged that shouldn't be, but will this be worth my time?

What else do I have to look forward to by cleaning it out? Somewhere I read better economy... who knows! Thanks!

Scott

[ScottyP5947]

Cleaned the tube out with compressed air and some carb cleaner. It was pretty easy to do, and I cleaned the sensor out too. Makes no difference with the idle issue at all, but I am glad to have gotten it taken care of before it causes me a problem.

Any other ideas?

Scott

[Dirk]

Originally Posted by ScottyP5947

Cleaned the tube out with compressed air and some carb cleaner. It was pretty easy to do, and I cleaned the sensor out too. Makes no difference with the idle issue at all, but I am glad to have gotten it taken care of before it causes me a problem.

Any other ideas?

Scott

It will help with chugging, that's about it. The miss/lope/skip you are speaking of is injector related. Get a contrib/balance and buzz test.

[ScottyP5947]

Alright! I have a buddy that works at the ford dealership in town (Thanks Matt!) and I had him run a buzz test - passed with flying colors. I had him run cyl contribution test and it came up with # 8 being out of balance. He's not 'the' diesel guy at the dealership, so when the guy who does diesels all day long came out he said "thing sounds great - what did you say your problem is?" I explained my situation and he said that it was more than likely the IPR (I may have the letters off -IPD?) he said it's a $350 part, and for me to 'run the snot out of it and don't worry about anything'. He said his truck does it too, and has for 5 years - no worries. When I asked about the # 8 injector, he said the same thing - not to worry, it's nearly 'normal', just get stage one or two injectors in a year or two when I feel like upgrading. He must have been able to tell that I wanted to do that someday anyway, but who doesn't?

What do yall think?

Scott

[DieselSVT]

Did you have the CPS recall done? Personally I'd make sure I had a black CPS in. Do the Cylinder Contirbution test again. If it passes Change the IPR and then maybe look at injector o-rings. My truck ran like poop. I put injector o-rings in it and they were shot. My skipping and sputtering is gone and it idles a hell of a lot better and it didnt really idle to bad before just seemed nervous.

[ScottyP5947]

Sure did about the CPS- this article seems to go closely with the other miss/skip article in this section. A lot of folks seem to be betting on IPR orings, IPR, etc. Someone even said it was the rotella 5-40 they were using. I am using that oil too... ? I am about to change the oil soon, and I may very well try something different - $90 oil changes every 5k is spendy!

Geez - I should just drive it until it gets worse? I guess that is better than throwing parts at it. I have also read to disconnect the ICP and see if that makes a difference, I have yet to try that, the wife has the truck in Tacoma now. Hopefully it doesn't get broken into this time! As for IPR orings - wouldn't there be some leak I would notice or would it be internal? I have already looked for oil in the ICP plug, BTW and there is none.

Scott

[atvquadsport]

The only way i see an oil like rottella causing a problem is if they were slacking on thier oil changes( i have been using mobil one but only because i can borrow it from work). I would check my fuel pressure at this point.

[ScottyP5947]

Yeah - sadly I changed the oil to delvac 15-40 and it seemed to make my mis/skip even worse. Seems like great oil and is rather quiet in the truck, but now it seems to have the miss a slight bit more than it did. I am guessing that is due to the move from 5-40 to 15-40 more than anything else.

Does that spark any ideas for anyone?

Thanks!

Scott P