put some two stroke oil in your fuel, worked for me...

 

How much two stroke oil and what did you use. like chain saw stuff, or the kind you used to put into your dirt bike fuel. any recommended brand?

What does the 2-stroke oil do if you dont mind explaining just bit?

 

I didnt want to replace my fuel pressure regulator so I ready so thread on here about people putting some two stroke oil in their fuel to lube injectors and fuel system as a temporary fix.

I ride sleds so I had some arctic cat apv oil (45.95/gallon RIPOFF) laying around so i just said screw it and poured a moderate ammount in. About the same ammount that is recommended for a standard fuel addititive.

 

I 2nd the two stroke oil suggestion. The white smoke wouldnt indicate a bad FPR, the rolling idle could. Does it sound loud at idle...and what I mean is the injector "knack knack knack knack knack.." Is it louder than other LB7s you have heard? If your FRP sensor is bad, it could be adding too much pressure at idle which makes the injectors loud and starts to F up a smooth idle. My 03 is quiet at 35kpa idle rail pressure, my 01 is loud and has a rough idle, if I turn my rail pressure down, it quiets up and smooths out.

And someone else chime in here, a cracked injector wouldnt neccesarily show a bad balance rate. White smoke says your getting too much fuel at idle... so either leaky injector (cracked, bad seat, whatever) or FPR sensor.

My guesses.

Start with the bottle of 2 stroke.

 

It was not louder than any other LB7 at idle IMO, but it did have a surge, and like I said, desired would not follow actual rail pressure at idle.

Cracked injector or leaking ball/seat would show a bad balance rate because it would be injecting too much fuel into a certain cylinder...which would cause a bad balance rate as the ECM tries to compensate for a cylinder that is overpowering the others.

If you look up in eSI (gm factory service manual that the dealers use), the diagnostic flow charts all point to a bad regulator, and say to replace it...I realize those arent always right, but every other LB7 ive had with these symptoms had a bad regulator.

 

well along with that I have some Ski-doo 2 stroke oil, ill run some through it and see what happens. and try the 2 stroke oil first.

Daschae, as far as your comments. the FPR is brand new just put it in on sunday. I dont know if my LB7 is loud in comparison to any others but I will take a look at the rail pressure. And so far last resort is possible cracked injector or bad injector I will keep that in mind. And I completely agree with too much fuel at idle. I guess were all just trying to figure out where its coming from.

Out of curiosity I'm going to try the 2 stroke oil, but i do run diesel clean additive every fuel tank. but if the oil works then it works. hahha.

 

subscribed....and bump for you phatfox77

 

My cousin's LB7 had a bad wire going to the FPR.

I think it sounds like injectors though.....My 2001 started loping at idle worse and worse along with white smoke......I swapped all the injectors and it has been running like a champ!

 

Andrew I sent you a PM regarding this.

For the people who are suggesting the two stroke oil...the reason you run 2-stroke oil is to free up a sticking regulator, if you read, you'll see he just replaced the regulator with a brand new one...so why would it be sticking?

The injectors all looked good, there were not any other codes, and the regulator command current (mA) and duty cycle (%) seemed right on what normal values should be...I am really surprised/confused a new pressure regulator did not fix it, all of the other LB7's that ive worked on that had these symptoms was for a bad regulator. Considering the miles, it was about time for it to go out anyways. Desired rail would not follow actual rail at idle, etc...

As I said in the PM, could also be wires going to the pressure regulator, but not REALLY likely in my opinion. Early 03-04 6.0 powerstrokes had an issue with this. Ive had to replace ICP (injection control pressure) sensors on early 6.0's because what happens is the sensor leaks oil into the connector, and the crap in the oil seeps into the wires and changes the wires resistance enough to not give a proper feedback signal to the ECM/FICM. But like I said, thats on 6.0 PSD's...Im not sure how oil or anything else would contaminate the connector on a duramax pressure regulator.

Andrew and anthony- the next step would be to check for good connections on everything, and trace the wires from the ECM connectors all the way to the pressure regulator with a multimeter to make sure there isnt anything causing resistance in the wire. Give me a call or let me know if you want me to email the wiring diagrams to you so you can trace them out to make sure the wires have perfect continuity/0 ohms.

Ben

 

So here is What Ben At Diesel works Said in regards to this post and he is the one who ran all the tests on my truck.

Ben's Responce:

Hmmm very strange. I cant see it being a CP3 issue because when we commanded 23,000psi at idle, it was able to sustain it. If the CP3 was bad it wouldnt have held 23,000psi.

Does it still throw any codes? Other than a fuel filter, I cant really see what else would be causing the issue. There isnt any electric fuel pump or anything on it, just the mechanical gear pump on the back of the CP3; thats what sucks the fuel all the way from the tank. Provided there arent any blockages in the line or anything, but then again at wide open throttle, we would see a drop in pressure if the fuel lines were blocked.

Bad ECM is possible I guess, but very rare. I wish we had updated with the latest dealer updates when you guys were here....not that that would have fixed it, but at least then we could 100% cross the ECM off the list of other potential problem spots besides the regulator. When he pulled the connector off the regulator, was there any oil or anything in it? Did the terminals on the connector look clean and dry?

As far as the injectors, they all looked fine, no fuel in the oil or anything so there shouldnt be any leaks or anything that could make the pressure do funny things.

Theres no computer reset or anything, every other LB7 ive had with those symptoms, cleared right up with a replaced fuel pressure regulator.

 

Just so it is covered.

2003 LB7. Two sets of injectors replaced before 42K. 102K miles now with no rough idle, no smoke, no white haze. Nothing but a smoother running, quieter Dmax that pulls like crazy. I use a combo of Diesel Concentrate AND Cetane Booster from Amsoil in every tank. IMHO it is worth testing, most that have tested this combination have had great results. I have heard zero negative feedback from those that have used the combo according to the instructions.

Anyone who would like to test it for themselves, let me know and I will get a couple of bottles of each sent so that you can decide for yourself whether they work as well as we claim....

Have a GREAT day and good luck with your issues.

 

Duratothemax,
I agree with you with everything that has been happening. I really wish the FPR had fixed the problem. I guess we just need to figure out whats cause that surge at idle and dumping the extra fuel....

 

Sent you an email with the schematics. The ECM is kinda a PITA to remove on the LB7's, let me know if you get stuck on anything.

Ben

 

I still think it is your injectors......

Injectors are the only thing that could cause the white smoke, unless you have a coolant leak.

 

the white smoke was unburned fuel; thats what the smell was.

 

Did the Injectors

I did the injectors this weekend. took me saturday and sunday. job went well, Duratitus injector replacement post was very helpful. Once again the idling white smoke problem has been solved by changing injectors. I changed all 8. Not too bad of a job, truck is running amazing!!!...

 

Glad you got the problem fixed, and good to hear my injectors worked good for you!

Congrats!

 

im having very similar problems with my 02 lb7 ive had it for three months now,it has 147xxx and i noticed the injectors have been replaced once already,but the smoking problem with it stumps me,when its nice out and sunny it wont smoke at all but when its damp and rainy or snowy out itll smoke,no loss in power,no loss in mileage,doesnt idle rough and no injector knock...and its only been doing it for about a month since i have owned it, i drive it a half mile down the road and the light smoke clears right out :help
thanks

 

:help so im having a similar problem... i have an 02 lb7 with 147,xxx and the injectors have been replaced .the smoke has got me stumped. it only really smokes when its snowing or raining (damp out) and when it does smoke it only smoke at idle and at drive for about a half mile down the road and itll clear out. i changed the fuel filter because that was real dirty. i have no loss in power what so ever no loss in mpg,its no louder than it was before it started smoking,no injector knock or abnormal sounds so i dont know.....:cookoo[1]:

 

How much of the 2 cycle oil should u put in the tank?

 

I have the same issue minus the smoke, 2002 lb7, had the P0089 code, surging idle, replaced the FPR and still have the surging and code. Must be the connection to the FPR or somewhere down the line?

Thanks Guys,

Spencer