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What did you do with your GMT400 today...or yesterday....

Welp. New issue just popped up on my dash! Took off to a friend’s house for dinner tonight and when I was getting up on the freeway on ramp my SES light came on! Still running fine I made it to my exit, let off the go pedal and the light off. Go a little further down the road step on the go pedal again and the light comes back on!! It did this several more times, press the pedal, light on, let off the pedal and the light turns off!! I’m assuming there’s an issue with the pedal sensor but my service pedal light isn’t turning on.
 
dbrannon79 said:
Welp. New issue just popped up on my dash! Took off to a friend’s house for dinner tonight and when I was getting up on the freeway on ramp my SES light came on! Still running fine I made it to my exit, let off the go pedal and the light off. Go a little further down the road step on the go pedal again and the light comes back on!! It did this several more times, press the pedal, light on, let off the pedal and the light turns off!! I’m assuming there’s an issue with the pedal sensor but my service pedal light isn’t turning on.
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Stop pressing that pedal!
 
dbrannon79 said:
Welp. New issue just popped up on my dash! Took off to a friend’s house for dinner tonight and when I was getting up on the freeway on ramp my SES light came on! Still running fine I made it to my exit, let off the go pedal and the light off. Go a little further down the road step on the go pedal again and the light comes back on!! It did this several more times, press the pedal, light on, let off the pedal and the light turns off!! I’m assuming there’s an issue with the pedal sensor but my service pedal light isn’t turning on.
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Code(s)???
 
Here's the codes. it's showing two codes. when I step on the pedal in park they will go active. no stumbling or anything, or no hard start. It seems to be running fine. I also looked at the data and the IP pulse width stays at 1.95 constant even when I rev up the engine.

IMG_4511.jpgIMG_4512.jpg
 
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I'm reading up on these two codes and see it can be a couple of things. failing PMD or the IP optic sensor! some are saying there is not enough lube in the fuel. I have been running Schaeffers summer diesel additive for the past couple of months without issue, same stuff we use at work.

I have a full tank of fuel in it now, so I can throw in some 2 cycle oil or some other lube in it if that's the issue.
 
the other thing that just came to mind is I just power washed the engine yesterday. I wonder if moisture got into a connector. I did hit the area around the IP fairly hard trying to get all the muck out of the valley under the intake. But it just started this this evening, the engine had had time to dry and it didn't do this any after washing it. I can't check it tonight. I will have to check all the connectors after work tomorrow. I get out a little early (4:30pm) for an appointment to get new work boots in town (company is sending me)
 
dbrannon79 said:
the other thing that just came to mind is I just power washed the engine yesterday. I wonder if moisture got into a connector. I did hit the area around the IP fairly hard trying to get all the muck out of the valley under the intake. But it just started this this evening, the engine had had time to dry and it didn't do this any after washing it. I can't check it tonight. I will have to check all the connectors after work tomorrow. I get out a little early (4:30pm) for an appointment to get new work boots in town (company is sending me)
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I would never hit that area with a pressure washer.
 
Well I didn't hit the pump directly, but got both sides down into the valley. I hope that's all the issue is. I surely don't need to become a member of a dead IP, though I know that will happen at some point.

After reading several other sites online stating it's lack of lube in the fuel, I just overdosed the tank with some power service lube I had left just so I have some piece of mind there's plenty of lube in the tank since it's full. I also just filled up on Saturday. I only have about 45 miles on this tank of fuel. I will have to remember to do 2-3 stopping jerks in the driveway in the morning heading to work so the tank is well mixed before hitting the road. my filter bowl is clear too.
 
dbrannon79 said:
Well I didn't hit the pump directly, but got both sides down into the valley. I hope that's all the issue is. I surely don't need to become a member of a dead IP, though I know that will happen at some point.

After reading several other sites online stating it's lack of lube in the fuel, I just overdosed the tank with some power service lube I had left just so I have some piece of mind there's plenty of lube in the tank since it's full. I also just filled up on Saturday. I only have about 45 miles on this tank of fuel. I will have to remember to do 2-3 stopping jerks in the driveway in the morning heading to work so the tank is well mixed before hitting the road. my filter bowl is clear too.
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If it dissolves in diesel, it will be full dispersed in less than 15 minutes.
 
Reading the safety data sheets, that is basically thinning out the diesel with non alcohol fuel lites (lighter than gasoline materials). It is designed for common rail engines how they can plug the filters easier because they have to be filtered so much finer.
Cant say its bad for the ip- but I would wanna see the friction/wear tests.
Bump in power/ mpg is easy when you add super unleaded to diesel- so don’t take that as evidence it is less friction.

Could it be the cause of the codes? idk. But I would be tempted to drain it and run straight fuel or fuel with stanadyne as a comparison.
 
Will L. said:
Reading the safety data sheets, that is basically thinning out the diesel with non alcohol fuel lites (lighter than gasoline materials). It is designed for common rail engines how they can plug the filters easier because they have to be filtered so much finer.
Cant say its bad for the ip- but I would wanna see the friction/wear tests.
Bump in power/ mpg is easy when you add super unleaded to diesel- so don’t take that as evidence it is less friction.

Could it be the cause of the codes? idk. But I would be tempted to drain it and run straight fuel or fuel with stanadyne as a comparison.
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which one? the Schaeffers summer additive or the power service?
 
The Schaffers is the one I looked up.
You have to be specific about the poser service- they MIGHT have one that is ok to add but all their stuff I know of has NO BUSINESS in our engine. That 911 stuff is an emergency use only just like the 911 implies as far as our engines go. Add it when you are willing to do slight damage to get the truck running. Thats it.
All that stuff is designed for COMMON RAIL high pressure.

Know which one extends the life of ours? Stanandyne. Imagine that. They built the pump and their oil works the best in it. The only other thing to do in a ds4 is moderate amounts of 2 stroke. Sorry but the best things that most the folklore is about with really helping mpg and crazy long life is in db2. We did dyno life runs at unical with straight atf and power was down less than 5%, fuel mileage was up nearly 50% and the ip life more than doubled compared to ulsd. It used to be common added service at semi truck shops to do flush/ cleanout of injectors and pumps. How did we do it? 100% dexron atf filled the fuel filters when doing the service. Cleans everything amazingly and the residule returns to tank assisted the rest of the tank full. But you simply can’t do that to a ds4. The Environmental Profit Agency put a stop to it by threatening and in some cases actually fined some shops for using a non ulsd fuel. This is why all the additives now days are rated as uls.

If your pump has been built for ulsd, great. You don’t need to add lube to get an acceptable life span from it. Adding lube to that pump doesn’t hurt it provided there isn’t any of the negative affecting stuff like fuel thinners (schaffers) or hydroscopic additives (diesel911) that outweigh the benefits.

How slippery is ulsd? Wanna use it in the crankcase? Transmission? Differentials? Why not? It is a lubricant. Oh, because it isn’t the proper lubricant to maximize lifespan of the component. Would it work using 5w20 in your differential? Yes. You could drive thousands of miles on it. But not 100,000 miles. ULSD is the same. It isn’t all snake oil- sometimes oil actually helps extend the lifespan of metal on metal friction.

Is the cost of the additive worth the added life of the ip and injectors? idk. You need to do the math and determine if it is for you. Working for oil & fuel company fleet full of 6.5s that many would crush 100,000 miles per year - we determined is was worth it. We tended to out trucks around the 300,000 mile mark regardless if it was 2.75 years old or 10 years old.

The reliability & mpg advantages of the db2 trucks was so much better that we ran many of them to almost 500,000 miles (Rebuilt major components obviously)
Lawyers had us dump them rather than risk a wreck on a rig over the 500 limit because it looks so horrible in court for a big company to do it if they find mechanical failure in truck/car causing the wreck. But it was no big deal to get over 300,000 miles from a db2 using atf with the fuel. Unical actually seriously considered selling a mixture of it as “super lube diesel” but marketing determined it would have negative affects on the other diesel. Plus they were already killing the more expensive chevron special additives gasoline by pricing.

One last consideration is water intrusion involving buggies. Oil saturated steel and aluminum is far less susceptible to damage from the munchers than raw fuel scenarios.
Plenty of testing done on that. Ive seen two 6.5 hummers fill up at contaminated place and one survived the other got a new ip within 2,000 miles. Wanna guess which one?
 
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Um ok @Will L. .... I think either I haven't drank enough coffee yet or you just talked in a circle.. honestly not sure which..
Are you saying additive good or bad?? I usually put ATF in my fuel during summer and Howes in winter.. (please nobody tell me it doesn't get cold enough in NY to gel fuel cause I've had it happen)..
It's been my understanding since joining TTS that ulsd doesn't have enough oil in it and therefore ruins pumps if you don't run a additive.. am I missing something?? My truck has 317k on it last I looked.
 
Thanks Will. I am with Stoney on it as well. my understanding since joining this forum and since owning this truck has been the same, ULSD doesn't have enough lube to keep our DB2's and DS4's alive and get their full expected life out of them without adding some type of lube. Stanadyne, power Service (not the 911 flavor but the everyday one) or 2 cycle oil and ATF. my rig has 295k on it and there is a date code sticker on my IP where it had been installed about half way through it's 28-29 year life, so just guessing the IP on it mow has about 150k give or take on it.

Will, I understand now what your saying about the fuel lites with Schaeffers and the 911 stuff. I will use up the power service I just poured into my tank and them switch over to Stanadyne (if I can find it locally) or just run 2 cycle / ATF in it at a 200 to 1 ratio.


Back to the issue at hand, I drove to work this morning all without any physical issues on the truck. starts up quick and easy, no miss, studering, no fish bite, nothing. I haven't noticed any power loss ether. only thing is that every time I step on the pedal and accelerate past 1400-1500 while driving, my check engine light turns on. as soon as I let off or get to a light cruising speed where I'm barley pressing the pedal the light turns off.

when I checked codes last night I am getting two codes. 35 - Inj. pulse width too short error and 36 - inj. pulse width too long error.

I will check all the connections on the IP and the PMD tonight clean them with a blow gun and re-apply some di-electric grease. then go from there.

I have a spare PMD ready to use behind my back seat all mounted on a headsink with an extension cable I can also try, but I will verify the engine harness first.

if all else fails to cure it, I can assume my IP is beginning it's decline to it's death. if this is the case, how much longer will it run... probably not much I would guess. if this turns out to be the case, this truck will get parked for a while as I can't afford to spend 1k on another IP right now.
 
Yes use lube additive- don’t use the mainstream crap being pushed for common rail diesels.
Use stanandyne, 2 stroke, or atf.
Don’t use anything with alcohols, hydroscopic compounds, power boosting compounds.

Realize that additives that will unfreeze or ungel (same thing) fuel is horrible for the ip. So is running gelled fuel so choose your poison. If an oopsy happens once in a while- fine. If you deal with it a 3rd time- make adjustments to your lifestyle like adding a fuel heater. The gm ffm was a huge improvement to the cube filter before it on the 6.2- but is by no means a good system. It is barely adequate for the majority of average owners. If you experience gelling- you do not fit in that category.
Upgraded liftpump with better filters is smart- and for gelled fuel adding the wazoo heater into that system is the best answer. The problem is not the fuel it is the temperature- so raise the temperature. Need a heating blanket on your tank- figure out the right way to do it. But adding liquid melting goo to fuel that makes it damaging to the ip is not the best solution.
 
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