2002 LB7 P1093 not CP3 - test? - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 13 (permalink) Old 08-03-2019, 10:12 AM Thread Starter
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2002 LB7 P1093 not CP3 - test?

I have a 2002 LB7 with about 175K miles and the injectors have about 30K miles (replaced by shop before buying the truck). Over the last couple of years when towing I would get a P1093. Most threads pointed to CP3 getting weak and since there were no other symptoms (truck started and idled fine, no smoke, balance rates at idle were good, etc) I decided that must be the issue. I didn't really start noticing lack of pulling power until last March but still day to day unloaded it ran fine so I just let it go until I had time to tackle the job. Last month at the end of a camping trip my crankcase overflowed with diesel (vibration at idle in stop and go traffic and the whole underside of truck dripping with oil/diesel when we got home). Admittedly I don't check my oil that often since every time I have it has been fine and there are no leaks and I don't drive the truck that much - so for all I know it had been slowly filling for quite some time. On this trip I did notice the oil pressure being lower than usual but not in any danger zone.

I read CP3s can leak fuel into the crank case so I figured since it was on its way out I should change it and see if I continued to get diesel in the crankcase but at lest my P1093 would be taken care of.

So it is all back together and runs fine - actually it runs EXACTLY like it did before - I have about 700lbs worth of large yard rocks in the bed so it is under a load and the P1093 came back when running an errand. No sign of diesel in the oil but I have only put 20 or so miles on it and if it was just seeping in before I think it should take a while to show up to where I could see/smell it - yes? BTW I replace the fuel filter at each oil change - but not this time after draining all the oil/diesel out - so I am pretty doubtful that it is that since I have changed the oil after I first started getting the P1093 code - but I might change just to be safe.

So... cracked injector body? Broken return line? Anything else it could be that I can throw a part at without removing the valve covers? I have a lift pump that I put on when I started getting the P1093 and made no change.

I really really don't like taking my truck to shops - quoted me +$600 to replace the belt driven vacuum pump that I ended up doing my self for about $100 - so ANYTHING I can do in my driveway I am game to try.

Thanks
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post #2 of 13 (permalink) Old 08-06-2019, 09:06 PM
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It really bothers me when I seen posts from new folks like you (5) who make time to do a thorough write up of your situation, then get no replies.

As Iíve said before, I fear many old timers here have moved on to new rides and the ones who are still around are beginning to weary of answering the same questions, over and over...

Where was I?

Oh yea, starting with possible ďfuel in oilĒ search this forum for ďoil spotĒ test which will give an indication if that problem persists.

Also, search is your friend (on this forum or Google) with many suggestions and tests that are fairly straightforward.

Hope I havenít insulted your intelligence, but in the current state of our forum, Iím afraid DIY is the order of the day .

Best

2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k
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post #3 of 13 (permalink) Old 08-06-2019, 11:11 PM Thread Starter
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Hi stevewaclo - I appreciate the reply.

Yes, search is good and I have used it quite a bit. But I haven't found anything that seems to fit these symptoms (after CP3 replacement) - and to be honest looking through search results threads gets tedious quickly. I like to think forums have those that don't mind repeating them selves or pointing to something specific where they answered the question previously - but I guess like you said most of those folks have moved on.

The more I think about it the more I think I didn't need to change the CP3 and that my leak is probably at one of the high pressure line to injector connections. I know if it is an injector I would replace those lines at the same time so I am probably going to replace them first and see if the code P1093 returns or not. On the high pressure side there aren't that many places to leak and get fuel in the crankcase. I haven't had time to do the paper towel test (no, seriously) but will when we get back from vacation on Monday.

Thanks again
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post #4 of 13 (permalink) Old 08-07-2019, 07:43 AM
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Thanks for your understanding.

Let us know about results of the paper towel test and weíll speculate further.

2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k
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post #5 of 13 (permalink) Old 08-14-2019, 07:52 PM Thread Starter
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So via the paper towel test diesel is in the crank case again. I'll be ordering new high pressure lines and see what that does.
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post #6 of 13 (permalink) Old 08-14-2019, 09:09 PM
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Thinking out loud...always dangerous.

The most common issue of fuel in oil I read about here is trouble with return line fittings and that would obviously not throw the P1093 since those lines are just low pressure plumbing, directing unused fuel back to the tank. On the other hand, high return rates, due to failure of the return ball/seat inside one or more injectors might disrupt rail pressure, but would not fill your crankcase with diesel.

Early in the production run, LB7 injectors had metallurgical problems that resulted in cracked and leaking bodies, but I believe all of those injectors are long gone from the gene pool.

Regarding your thoughts about replacing HP lines, if you look closely at your engine you will see those lines from the common rail to each injector are external to the valve covers and any fuel leak there would result in diesel escaping the system (and a P1093) and soaking the top of the engine, but not getting under the upper valve cover and into the crankcase.

Something else I should mention in regard to replacing those lines. If you look at the HP connection atop each injector you will notice there is a small gap around the nut and the line. That gap accumulates water and then rust and when the line is removed, all that debris inevitably falls into the top of the injector, where there is a screen (for all the good it does) and is impossible to remove without injector tear-down. Since most folks who have dived that far into their engine are there to R&R injectors, the junk doesnít matter, since the old injectors become cores.

In your case, that rust is going to be there (unless someone sealed around the aforementioned gap) and you know where itís going to end up.

Back to bad HP lines, there should be external diesel somewhere if one failed, but again I havenít read of that often, although the connection to the injector has been known to leak. But again, where are signs of external diesel and how is it getting past the seal around the injector and upper valve cover?

Any failure of HP lines should be identifiable by using tissue or somesuch to absorb any leaking fluid.

I donít need to remind you, but I will, high pressure diesel is DANGEROUS so check with utmost caution.

Well, Iím afraid Iím not being much help here and sure wish someone else would join the conversation.

Only thing that comes to mind is maybe you do have a cracked body (as unlikely as that would seem) but you said the engine is running fine. (???)

There are inexpensive apps for iOS and Android that can be loaded to a smart smart phone and, with a comm device in your OBD2 port, read balance rates (plus lots of other useful 411) and would tell you if a cracked injector is bleeding off rail pressure. TECH2 is what the big kids use in shops, but very $$$.

Finally, you mentioned that ď...since March...Ē towing performance is degraded. Other symptoms?

Címon gang, help this guy out!

Best

2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k
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post #7 of 13 (permalink) Old 08-14-2019, 10:30 PM Thread Starter
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Wow! - thanks for the comprehensive and thoughtful reply.

So I guess I don't know or understand how the high pressure line connects to the injector. It looks like the connection is well below the upper valve cover even though the nut is outside so if that connection is bad the fuel would spray down at the injector or fan out but still be contained by the valve cover. I am thinking I could blow that space you mentioned out with compressed air before loosening. I am in Norcal east of the bay area which means low humidity etc. so maybe there isn't that much rust.

I have Torque on my phone and have checked the idle balance rates and they are all very close together. Although I have read lots of contradictory info on what they should actually be and what is good or bad - but since they are low and consistent from one to another and there are no other injector symptoms I think they are good - oh and only have 30k miles. Is there any other app that can do more I should look into?

As for the truck's performance the reduced towing power was just on the long grade leaving Pismo on 101 - slowed to about 45 when I could hit 55-65 when it wasn't throwing the code. After that climb there isn't much to climb the rest of the way home and it did fine cruising at +65 and I think I actually got a little better mileage (?) that trip. I am pulling a 35 ft 5th wheel that weighs about 11K. The truck is bone stock except for the lift pump I put on trying to mitigate the need for a CP3 I thought I needed.

It starts, idles, and drives fine or what I consider normal with no smoke. I have owned the truck about 6 years and put +30K miles on it with no problems beyond glow plugs until now.

Cheers
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post #8 of 13 (permalink) Old 08-14-2019, 10:32 PM Thread Starter
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Just remembered I did replace the belt driven vacuum pump too - so not quite as trouble free as I said above.
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post #9 of 13 (permalink) Old 08-15-2019, 12:22 AM
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You are correct!

Been a while since I did my injectors and I forgot how the HP lines connect to the injectors .

As you can see from the first photo, the connection to the injector is long and does indeed extend down through the seal on the upper valve cover.

The next photo shows injectors as seen going into the upper valve cover, HP lines on. Notice the gap between the tubing and the fitting where water collects.

Another photo of the injectors peeking through the upper valve cover, with HP lines off.

The last photo shows my concern about rust buildup in the HP connector and as you can see, it falls into the top of the injector when the line is removed. Many folks arriving at this moment think the rust is the source of their problems, but it is not on top of the injector until the line is removed. Left alone, it stays out of harms way.

And the junk in the picture is only what is visible to the eye. Remember, our fuel filters are sub-10 micron for a reason, and Iím afraid there is no way to keep that mess out of the injector once the line is disconnected.

I fear replacing just HP lines may ruin any injectors that are functional.

Excellent you have discovered Torque and read your balance rates. Unfortunately, without knowing return rates, balance rates may not tell the whole story since they only tell you the difference between injectors. In other words, the Fuel Injection Control Module (FICM) may be maxing out the pulse width (ďonĒ time) of every injector and BRís would be in spec and close to each other.

But in your case, that would mean every injector is dripping instead of shutting off and your engine would be hazing up a storm at idle! And unless you have injectors stuck wide open (and with similar BRís, it would have to be every one!). Also, a stuck open injector can be a disaster due to hydro-lock of a piston, as well as fuel in oil.

Arghhh .

This is just not making sense.

One final thought, there is a seal in the CP3 which can fail and leak fuel into the oil. But why the code!? Does that seal, if defective, compromise rail pressure? Iíll let you check that out.

Iím going to bed...
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2003 GMC Sierra 2500HD SLE ExtCab CA Emissions; 155k; Allison 1000 w/Transynd X2 Flush & Fill; 8' bed; AFE/CAI; MBRP 4" Exhaust; Side Tint, 33% VLT, rear, Limo; Smittybilt Stainless Side Nerf Bars; Sprayed-in Bed Liner; MadJack Fuel Filter Access Door; Regular Used Oil Analysis (latest available on request), Blackstone Labs; EGT/Boost Gauges; Dual Chrome Dipsticks, JC Whitney; Stainless Steel fuel filter head bleeder screw; New WP and Hydroboost; Billet Aluminum Fuel Filter Housing Spacer; Professionally repaired instrument cluster (new steppers and lamps); Does anybody ever read this s%#t?; Injectors under warranty @ 70k; 2nd set DIY @ 155k
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post #10 of 13 (permalink) Old 08-16-2019, 09:48 AM Thread Starter
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Regarding your last comment about the CP3 seal - recall that I replaced the CP3 because of the P1093 and had read the seal could leak which would explain the fuel in the oil. But since it is new (reman) and has the exact same symptoms I am very doubtful the CP3 is the culprit. I went ahead and ordered replacement high pressure lines and valve cover seals. When I take off the first one I will learn a lot about how viable changing them out without doing the injectors will be. I will post how that goes if there aren't any other thoughts from the community.

Cheers
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