LBZ: P0090 That will not Clear

[Sgp93gsx]

Ok guys, been searching for 2 days. I seem to find a lot of dead end threads. I can't believe these past problems weren't fixed. I'm sure they found their issues and just not updated.

I have an 06 LBZ. Airdog II 165. PCV reroute. Dsp5- Idaho Rob. EGR delete. 4" through a muffler. Everything else is stock.

This all started about 3 weeks ago. Intermittent loping only at idle. Couldn't duplicate it to diagnose. As time has gone on, it's gotten worse. Added some 2 cycle oil seems to help. Didn't have any left to add on this last tank. I have also noticed, while the truck is idling odd or surging while at cruise, my temperature gauge is fluctuating between 160/200 quickly. Not flickering, but sweeping. The issues started getting worse again. Right up until the engine limped and threw a P0090 code that will not clear. I did not get any other codes. No low or high rail pressures. I have battery + voltage on the the purple wire going to the FPR seems like 2.5 volts across the purple/yellow wires. And 1.25 V- on the yellow. Obviously the purple wire is lighting a test light. But not the yellow with the test light lead on the + . I am not noticing ANY difference in the running of the truck with the FPR unplugged. (Like an old diesel)

I guess my question really would be, Is it possible to have a FPR that is shorted internally causing all my issues? Even the temp gauge? Never did this before. I cannot even clear the code without the truck running. So I am assuming I have a wiring issue. I went over every area that I could get near looking for anything rubbing. All harnesses look great. I cannot get my probes down to the FPR to ohm the internal coil without disassembling the truck. I have a new FPR on its way as I figured I would need it sooner than later as the 2 cycle was a bandaid. Just didn't think I'd need it this soon. I would rather not pull it apart as I can still move it around until the new FPR get here.

Any help from people that have been through this is greatly appreciated. I have just read too many threads where others have replaced their FPRs and still had the same issues. Although most of those turned out to be worn through harnesses.

Thanks in Advance

 

[Sgp93gsx]

Bump. Just looking for someone that has had FPR issues. Anything close?

 

[motoking_1990]

Can't believe no one has commented on possible solutions.

Sent from my C811 4G using Tapatalk

 

[Sgp93gsx]

Can't believe no one has commented on possible solutions.

Sent from my C811 4G using Tapatalk

It may just be, the people that have dealt with this issue are busy enjoying their repair At least I'd like to think so.

I have a new FPR on its way. Hopefully will be here Friday. If it fixes my issue, I'll be sure to post it. Would surely have made my search for answers easier.

 

[JoshH]

The most common cause of this problem is the connection at the jumper harness that runs down to the FPR from the top of the intake neck.

 

[Sgp93gsx]

The most common cause of this problem is the connection at the jumper harness that runs down to the FPR from the top of the intake neck.

Parked the truck where it can sit and started pulling it down. I found the harness you were talking about. It's a little odd. I have 3 wires in, 2 out? I'm assuming a possible diode back for a sensor. Either way, none of the wires in the jumper harness are shorted to each other. I checked the FPR ohms directly on the FPR not through the harness. I am getting 3 - 3.4 ohms. Does anyone have a known good one that they can ohm out so I know if I need to keep digging into this thing?

The truck just turned 170K should I just replace the FPR because I have one on its way and it'll be due sooner than later? Are these things known to go bad by mileage? I do plan on keeping this thing for a LONG time. also, any recommendations on what is necessary to remove? I hate taking off more than what is needed to do a repair.

 

[BobbyBDirtyMax]

Sounds to me like it's the FPR itself if all the wiring is checking out good. My LLY did the same thing early last year, I'd replace the FPR and be done with it. They wear out over time just like anything else, and make sure you replace it with the one for your motor, LB7, LLY ect ect, in your case LBZ

 

[Sgp93gsx]

As bad as that sounds, Awesome... I hope that's it.

Thanks for your help.


Can someone tell me if the pipe that moves in the Y bridge comes out or do you just remove the bridge itself?

 

[Andrew]

It comes out but be careful not to cut the o rings when you put it back in

 

[BobbyBDirtyMax]

It comes out, has a rubber O ring. Just wiggle it and it'll come out and give you plenty of room to get to it. I use a T25 torx bit and 1/4 inch gear wrench. Works pretty good

 

[JoshH]

Parked the truck where it can sit and started pulling it down. I found the harness you were talking about. It's a little odd. I have 3 wires in, 2 out? I'm assuming a possible diode back for a sensor. Either way, none of the wires in the jumper harness are shorted to each other. I checked the FPR ohms directly on the FPR not through the harness. I am getting 3 - 3.4 ohms. Does anyone have a known good one that they can ohm out so I know if I need to keep digging into this thing?

The truck just turned 170K should I just replace the FPR because I have one on its way and it'll be due sooner than later? Are these things known to go bad by mileage? I do plan on keeping this thing for a LONG time. also, any recommendations on what is necessary to remove? I hate taking off more than what is needed to do a repair.

One of the wires is a shielding wire.

 

[Sgp93gsx]

Went back to it this evening. Pulled the pipe out, not too bad. I just didn't want to force anything and have to buy more parts than needed.

BobbyB Thanks for the tip. I ended up having a short T25 bit and used a magnetized drill adapter (helped hold the screws also) and 1/4 socket on a 1/4 ratchet. Viola, the FPR was out.

Has anyone ever had their FPR out, hooked to their harness and seen if it "clicked", moved, made any noise at all, letting them know something was actually happening with it?

I will say again, when I unplugged it and ran the truck, it sounded no different than when it was plugged in. So basically doesn't that mean the FPR is not opening at all and the rail is running at max pressure? Would a locked up FPR throw a P0090 code? Can the ECM "see" too much load through the supply wire with the FPR locked up?

My new one will be here tomorrow so I may be able to answer my own questions. Either way I'll report back in case someone is searching for an answer in the future.

 

[Robby Avery]

Good read here hope the internally faulted fpr is your problem install the new one first to see if that fixes your problem if it does dissect the old one so you'll know for future reference what burns and or shorts out just some food for thought :thumb:

 

[Sgp93gsx]

The new FPR arrived. It Ohms out at 2.8 Seems like more of a short. I guess it really depends on how the ECM controls it. When I get it installed I'll post the results..

 

[Sgp93gsx]

Here to update... The new FPR did nothing but show me exactly how to install one. Maybe give me the piece of mind that it is new...

My first clue was the water temp. Sweeping and the truck surging basically in unison. If you are having multiple electrical issues, than look for an electrical, not mechanical problem.

Turns out. After installing the new FPR and it not changing a thing, more searching went on.

This thread: http://www.dieselplace.com/forum/63-...got-worse.html

Which lead me to this thread : http://www.dieselplace.com/forum/63-...hip-later.html

If you look at the loom coming from the ECM. It's laying right up against the drivers side inner fender well. I checked every wire that was remotely close to the FPR and the water temp sensor and everything looked great. Never did go that far from sensors. Either way, I've never been so aggravated and happy at the same time.

The trucks running great, I have a new FPR (that I didn't need) just have some insulation to fix now. Definitely going to add some extra protection in that area. If you're reading this, a short piece of foam insulation against the fender well, around the harness, will stop any of the issues I've just encountered.

Also, if you've searched and found this thread, I wish I would have. Surely would have saved me a lot of time and aggravation...

 

[Sgp93gsx]

Here are a couple photos so you can see just how small of an area can screw you up. The first pic here is what I found when I flipped the harness over that was up against the drivers side inner fender well.

 

[Sgp93gsx]

This is what it looked like when I cut the tape open. Notice the brown/ tan twisted wires. The brown wire is rubbed through.

 

[DIESELMAFIAPER.LB7]

Nm you added the second pic