Help from all DMAX Techs needed

[tx dave]

Situation: 01 DMAX: I put it in the Dealer 0ne Month ago: Previous Post: Here's What they did: new injector cups and seals, new head gaskets, valve job and pressure checked , new FPR, new fuel filter: The truck will run but is very none responsive, NO Codes set, Pedal to the metal and the back tire won't even spin on gravel, You can hear the turbo working (which I very seldom heard before). The dealer service manager doesn't want me to have it back until it is right but they are at a loss since no codes are being set and the TECH 2 has everything working. I told them I would ask you guys and see if maybe someone has had this happen to them and knew how to or where to start looking.

[Mark Rinker]

If power is down, but no black smoke when floored (unburned fuel without enough air present to burn it) then I'd say you aren't getting proper fuel pressure. Not sure why it wouldn't be setting a code though...maybe one of our GM techs can chime in here and suggest a test or two to confirm/eliminate this.

The truck was really apart under the hood for all the parts they threw at this old girl...maybe something simple like a blocked/crimped air inlet duct?

What else could it be?

[Duramaster]

Do you have any numbers that you can post? Just because they replaced the FPR doesn't mean all is ok. How much fuel pressure is the pump actually developing? Low fuel rail pressure could be injectors returning too much fuel, worn out injection pump plugged fuel filter or even a "GAS" cap that has been installed in place of a "DIESEL" cap. What kind of boost pressure is being made? Are there any transmission codes? Have the tech actually go into the TCM and check for codes.

Here is another idea.............. When the tech had the engine apart, did he/ she put any rags over the Charge Air Cooler tubes to keep dirt out of the CAC itself? Have they performed a pressure test of the CAC? Is there any kind of restriction in the CAC system?

Is the truck in 4WD by accident? How about a PTO switch turned on which will limit the engine RPM's?

Hope some of this helps. ;)

[tx dave]

Duramaster: I was at the dealer ship everyday with the mechanic ( not all the time but for a couple of hours aday) Fuel pressure was 13000 before and 26000 after fpr. Boost pressure initially by Tech 2 was at 13 and raised to 14 at full throttle. The boost sensor was replaced (right side of intake or valley) Boost went to 33 after. Not sure about the CAC but we did check all the clamps (search here showed I think MR had this problem and that was the culpret. 2WD no PTO switch. I've owned her since 50k, my sister bought it new, so the cap is good. I had more stock power than I ever used and took it in for the bubbles in the coolant. Now it runs like a sick cow and I'm easy going but I'm still pissed, I want my truck back not this blue thing I don't know. To tell the truth, to me , it sounds like its not getting air, Isn't it with a diesel, fuel and air it runs, take away one and it doesn't.

All the other number from the TECH 2 I really can't remember

[Kennedy]

If all checks out OK externally: Injectors

If they didn't wire wheel the tips (screws them up) the junk that works loose from the lines when removed got into the injectors. This is something that I have seen/heard more than once. Enough that I don't think I'd ever pull one apart without replacing the injectors or at least having them thoroughly tested.

[madmatt]

I got nothin to add!!!! whats the fuel system vaccum? Act vs. Desired rail pressure? What happens when rail pressure is commanded to 160Mpa??? TPS read full range smoothly???

[tx dave]

I have ran a copy of all the replys and will give it to the service manager this morning. I didn't see the injectors cleaned with a wire wheel but one of the days I was there I looked at them and the tips were shining so maybe that happened. I'll let you know how it comes out.

[Duramaster]

Another brain FART...... How about the exhaust being plugged?

[Jake99Z71]

Is the waste gate broke? I've seen one that broke apart, so truck never built boost.

[tx dave]

Here's an update: still won't build power. The tech finished work on an 03 this after noon. We ran my 01 up to normal (test drove) temp. plugged a TECH 2 into each, side by side, the reading were real close on everything (except egr stuff) He's going to pull the exhaust apart tommorrow and check for restrictions. He said he blew air through the CAC this morning but will look at it closer after the exhaust. We are scratching our heads. TECH 2 says all is ok but its not. Fuel rail pressure commanded to 160 produced 158/159. The TECH is on a mission to find out what is wrong. I just wander at what point do they say this is the best you get back because the TECH 2 says everything is working right. And at that point what do I do knowing the thing is not right.

[tx dave]

Here's todays up date: Removed the exhaust pipes on the engine (all OK), pressure checked the CAC Held 30 psi for 30 minutes. They are going to get a vacumn gage from another dealer and vacume check the fuel return lines. New Fuel filter yesterday. If it still won't run tommorrow the service manage said he was going to take it to another dealer that has a lot of diesel techs for a second look. My opinion, the tech wheeled wired the injectors like JK said and screwed them up. Or forgot # 1 was on the right side and timed the vavles backwards. I don't know but we'll see. at least the dealer is picking up the tab on the rental truck starting tommorow. I just hate to see the bill they will probably try to stick me with. Already at $5k.

[madmatt]

WOW,,, they don't even have a fuel system vaccum gauge???? At this point I think I'd do a cylinder leakdown to make sure all valves are seating properly,,, after verifing a good fuel supply of course and was sure everything looked good on tech2.

[tx dave]

Up date: They wanted me bring in my Edge /juice. I hooked it up Saturday morning and I was only getting 3 for boost @ 3000rpm. The Tech 2 had my boost at 30 or so the other day. The mechanic wasn't there so I left it hooked up. This morning the service manager said they were going to drop the fuel tank and check the sock filter in the tank. This truck was running fine when I took it in and now it is a real dog on take off but will go 70 and 80 mph but feels like it is dragging or just lacking. I was told they were going to get in touch with the detroit boys ( or someone like that ) for tech assist but had to do everything first and record all the data. The parts man said he watched the mechanic clean the injector with the wire wheel. I'm beginning to think they are doing all this just to put off the inevidible of having to replace my injectors at there expense. Can any of you guys tell me the truth, Am I getting the run around or is all this really what they have to do to cover all the bases for my piece of mind and their justification for screwing up my truck. I haven't been told but do you think I'm going to be expected to pay for all these hours of looking for the problem it didn't have before I turned it in.

[madmatt]

If they find something wrong not related to anything they did, then i would say you will be expected to pay. If it goes back to something they laid a hand on,, they should most def eat this bill.

[tx dave]

Final update: Got my truck back today. It's still not running like it did but I am building 19 on boost and with the edge in level 2, it runs almost like it did. With all they did to it (especially new head gaskets) I should be able to get a million miles out of it now. I'm going to pull the 5th wheel this weekend and see what it will do. Many Many thanks for all the help and comments you guys gave.;);):eek:.

[madmatt]

well what did they find?

[tx dave]

Matt, They didn't find anything. The Tech 2 still said everything was OK. He cleaned the pickup screen in the fuel tank and the fuel heater. The mechanic did say he thought I still had a fuel delevery problem ( maybe injectors ?????) I'm kind of between a rock and a hard place. After 35 days of having my truck and going through everything and rechecking everything there is still nothing I can put my finger on BUT I'm open to any suggestions. I'm thinking about puting a new waste gate solinoid on just for my piece of mind and a new K @ N filter in my Volant housing. But at least I have it back and it won't cost me anything to tinker with it over time.:cool::rolleyes:

[Duramaster]

What kind of MAF reading are you able to get while observing with the Tech2? You should see around 400 gs depending on year/ engine/ and mods. Sometime more. I had a 2007 LBZ the other day with big exhaust that was consuming 460 + gs according to the MAF. The usual readings on the LB7 with stock exhaust is 390 or so.

[DmaxMaverick]

The LB7 does not have a wastegate solenoid. The WG actuator is driven solely by compressor housing pressure (purely mechanical). The WG is spring-loaded closed, and opened by compressor housing pressure.

[tx dave]

OK forget the waste gate actuator, No K &N maybe Amsoil (everything else is amsoil, through out) I don't know the MAF readings but I pulled it yesterday when I got home and cleaned it up really good. The Tech said it was working well. I also rerouted some wiring, and hoses that were touching the engine and added some split plastic pieces here and there. I'm going to run a tank with Sea Foam and see what that does. I've ordered trans fluid from amsoil and new filters from ebay so I'll be changing that this weekend. Other than that I'm going to drive it like I stole it , or like my X wifes husband is trying to catch me so he can give her back.:)