LLY: Rough inconsistent idle with #5 injector +5

[rmacdon375]

Hey all.

I'm new to the Diesel world and was recommended to join the forum from others who have had nothing but benefits from your assistance!

Bought a 2005 LLY not long ago and since I've gotten it, it's had an inconsistent rough idle; it's not too noticeable but enough to make the truck shake oddly every now and then.

Originally took it to my local BD dealer who said everything checked out fine so try an EGR Delete. EGR delete did not Help the problem and I brought it back a couple months later. This time, they said balance tests showed #5 injector was +5 so they recommended a new one and glow plugs due to codes.

I did the injector myself (and glow plugs) but this minor rough idle is still present. I haven't gotten a balance test done again but did do the icepick trick and checked the FICM wiring while under the hood.

Do you think a +5 would be enough to show any signs like a rough idle and if not, any ideas of where to go next? Possibly air in fuel or Fuel pressure regulator?

Thanks all!

 

[rmacdon375]

Hmmmm and it looks like my amateur user skill for this forum showed up in full colors with my posting of this thread in the intro's...my apologies. I would fix it if I knew how

 

[dmax711]

Make Sure you check wiring very well. Could be a few things if injectors and wiring check out.. first I would pop out the crank sensor and Make Sure the reluctor Wheel isnt half hanging off. You Really need to kool at fuel pressure, desired vs actual. Your f.p.r could be on its way out.

 

[rmacdon375]

Thanks! I may just take a better look at the wiring to ensure I covered those basis first. As for the actual vs. desired, I am going to take it into a diesel shop and see what they say so will get them to do that for me.

Thanks again!

 

[Kappa9012]

Has anyone checked out the fuel pressure regulator on the Cp3? Fill out your signature so we know more about your truck.

How many miles are on your truck?

Welcome to the sight.

 

[rmacdon375]

Has anyone checked out the fuel pressure regulator on the Cp3? Fill out your signature so we know more about your truck.

How many miles are on your truck?

Welcome to the sight.

Thanks for the response.

I took my truck to BD and they spent about 15 minutes with it, came back and said it needed a new injector (#5) and glow plugs. They based this off of the balance test and I specifically asked about the FPR and I was told it was good.

Does that make sense that they would be able to diagnose a fuel injector just off of the balance test and test the FPR all in that time frame? I am still thinking it has to do with the FPR myself.

 

[skintback]

You say #5 was at +5 and you changed it but the ruff idle is still there you might want to check compression just to rule that out and i have seen the ice pick job not work and #5 does not have to be the problem it could be trying to make up for another one thats not putting out enough firing order 12784563

 

[rmacdon375]

You say #5 was at +5 and you changed it but the ruff idle is still there you might want to check compression just to rule that out and i have seen the ice pick job not work and #5 does not have to be the problem it could be trying to make up for another one thats not putting out enough firing order 12784563

I was worried about the compression issue...I am thinking BD should have spent a little bit more time diagnosing than assuming changing #5 out due to high + balance was a little premature.

I'm gonna bite the bullet I think and pay $200 and get Bernhousan Diesel to play with this and diagnose it.

Thanks for everyone's input.

 

[baddaddition]

Hey fellas I know this isn't the place to post a new question but still getting use to the forum. have an lly in the shop cranks but wont start no security light tried relearn no go I installed a cts and it says csps crank sensor. long story short a customer called me and said he put a high idle switch on and now it wont crank......... after two days with the truck im beginning to think it had problems before but insist it started AFTER THE INSTALL. then he tells me he remove the connectors off the ecm but didn't disconnect batteries.. ok???? its an 04.5 lly with only 80k on it any advice would be great. gonna hit the hay for a bit but hopefully some direction will be presented over night. Thanks in advance.

 

[ALLY Fox]

Thanks for the response.

I took my truck to BD and they spent about 15 minutes with it, came back and said it needed a new injector (#5) and glow plugs. They based this off of the balance test and I specifically asked about the FPR and I was told it was good.

Does that make sense that they would be able to diagnose a fuel injector just off of the balance test and test the FPR all in that time frame? I am still thinking it has to do with the FPR myself.

High balance rate doesn't automatically mean that injector is bad, it could mean the injector is trying to compensate for low compression in that cyl etc. I don't know anything about BD, but some mechanics are fooled by the fact that Duramax cyl numbering is not the same as GM gas motors, cyl1 is on the right side. Seen a lot of wrong injectors replaced because of that.... I think EFI Live V2 uses the same convention. Do a "bottle test" to check FPR, a search should tell you how.