Ok, here is the story. I have to trip to Wichita Falls TX from Phoenix to fetch my lovely bride home. I got 3/4 tank of fuel left so I top it off at a at Circle K on the way out of town. The weather was cool and damp from Tuscon through NM. Now I am not letting the grass grow beneath me and have the cruise set at 80 mph. The engine temp is at 180 and stable, Trans Temp at 145 and stable, oil pressure at 70 and stable, EGTs at 600-700 consistantly. Just outside of Lordsburg NM headed towards Las Cruses I thought the engine noise starts to increase, but I turn up the radio a little more and keep the hammer down -- guages show no changes, outside temp at 42 degrees F.


About 40 miles from Las Cruses NM, I can hear the engine, and now it sounds like a Cummins! Trans Temp is now at 160, Engine Temp no change, Oil pressue no change, but I did notice that there is now a head wind. Noise is getting louder (no radio now http://www.dieselplace.com/forum/smileys/Unhappy.gif) and the Trans Temp is at 165, everything else is No Change. Fuel guage is at just under 1/4. Plan was to fill at Las Crusis so I pull in. At idle engine sounds normal. 21 gallons of fuel (16.8 mpg @ 74 mph ave), no oil used (changed oil & filter about 500 mile prior to trip), air filter sensor is still at 0, trans fluid smells ok and level is normal.


I crawled under her, smelled, looked, & scratched my head. Jumped back in and started her up and headed to El Paso and points East. She ran like a champ, no noises, everything acts and sounds normal, trans temp back to 145. Fact is, I caught a tailwind at El Paso that stayed with me clear to Amarillo. Next fill up she got 19.8 mpg at 77.6 mph average for 460 miles http://www.dieselplace.com/forum/smileys/Big Smile.gif. No rattle/clatter Cummins noises again the rest of the round trip.


Ok, so if it was 'bad fuel' how come it went 300 miles before it started to act up? What else might have caused it? The head wind was maybe 20-30 mph, but the terrain is pretty level in that part of the world, so I am not sure how much of a factor that should be.


I am not really worried right now, hell she is running like a top right now, but should I be looking for something else and should I be concerned? http://www.dieselplace.com/forum/smileys/Ermm.gif


Thanks, MitchEdited by: hoot

What RPM were you running in the headwind?


I believe above 2,700 or 2,800 rpm the pilot injection shuts off and the engine is much louder, more like a Cummins.


Just a thought.

Thanks for the reminder, I was going to mention that the RPM never got above 2400. Also, forgot to mention that I run my Hot Rod Diesel at level 4 with the regular juice unit, unless I am towing.

Yep, probably running like a top with the pilot injection turned off. I could be wrong, but thought it turned off at about 2650rpm.


On edit: But who knows how Edge has it set up?Edited by: Ray403Dmax

Ok, lets say the pilot injection was turned off, 3 things - why did it not do it again, even though I was running a little faster later in the day? and with the pilot injection off would would that have any effect on the transmission temp but not the engine temp? and finally, what kind of performance change would that bring on? I mean, other than the noise, the truck seemed to run fine it was just noisy.

I was thinking the engine rev's were up to over come the headwind, with the cruise set at 80mph. With a tailwind you don't need as much power.


You indicated you were traveling at 2,400 though, so not sure.


If you want to see how it sounds with the pilot injection off, run the truck in 2nd or 3rd around town and run the rpm up to rev limiter. If it sounds the same then that's it.

SS396, Thanks for the suggestion, Hell I dont want to have any surprises right now. Had this truck about 18 months and this trip brought the odometer to 32500. Yea I got the GM extended waranty, but still dont want any surprises.


Keep ya posted

The Juice has some strange pilot injection operation when the truck is cold, so it seems to depend on more than just RPM. Just guessing here, but I'd bet it's something to do with turbo boost. So less wind resistance (load) required less boost and maybe pilot injection wasn't turned off when you were going with the wind.


For the tranny, of course more load (or wind) increases temperature. If you're going 80mph with a 20mph headwind, the truck is working through 100mph equivalent wind resistance. Seems reasonable for pilot injection to turn off and the tranny to heat up a bit (neglecting possible flow regulation through oil cooler).


As a side note, I can picture that stretch of road as I've driven it many times. http://www.dieselplace.com/forum/smileys/Approve.gif

Once the pilot injection is 'off' what does it take to turn 'on'? I did vary my speed from 80 to 55 to 80 on that last 40 mile stretch and the engine noise level seemed to stay about the same, with variances in the RPM of course. Is this on/off/on of the pilot injection a digital occurance (immediate) or is a gradual thing, i.e., slowly on/off/on?

Ray,


on a side note.... the highest freeking price for diesel or gas is in this valley! its cheaper in Casa Grande by 15-20 cents a gallon. Once I crossed the AZ-NM border the prices dropped almost 50 cents! Delivery costs my butt! http://www.dieselplace.com/forum/smileys/Disapprove.gif

Sounds like ya got a Juice problem, Cool wet damp problem....Was it throwing gray smoke, Did it sound like you threw a rod?????. Did the pedal disappear, or did the noise get worse as you got "on" the pedal. Did you smell raw diesel. Did your EGT's dive??? Tell me more


Been here before almost 2 years ago now. Sounds like a problem I had with my juice box.


Wont ever happen again unless its cold/damp/rainy.........


Bill

Stupid question? What the heck is pilot injection? And someone please tell why it is necessary? http://www.dieselplace.com/forum/smileys/Confused.gif

I'm betting it was just the headwind making the engine work harder to maintain your speed. I seriously doubt there's anything wrong. Your RPM's wound be exactly the same whether you've got a headwind or a tailwind, your torque converter would be locked. The tranny temp. gauge probably went up due to the engine working harder due to the wind as well.

Stupid question? What the heck is pilot injection? And someone please tell why it is necessary? http://www.dieselplace.com/forum/smileys/Confused.gif


Pilot injection is necessary because it is the reason that the Duramax is such a quiet engine! The difference between the Duramax and the "rock crusher" Ford, Dodge and previous 6.5TD GM diesels is pilot injection - which shoots a small pre-ignition injection shot before the main injection to start the combustion and silence the injection burn wave front which creates the standard diesel rattle. At high rpms, the piston dwell time at top dead center is too short for a double injection shot - so the event becomes a single shot (pilot injection off) which produces a wave front and the diesel rattle.

Sounds like a Juice thing to me, not having one and all. Last month I drove down to San Diego. On the way down I noticed my Pyro was reading higher than I'm used to seeing and the boost guage was also elevated. The tranny temp was normal. The only change in engine sound was a more prominent whine from the turbo. I knew from these indicators and the way the wipers were skipping over the glass that I was in a ferocious headwind. Sure enough, when I fueled up at the Frazier Park off ramp, my mileage was way below normal. On the way back in more reasonable weather the temps and sounds were normal as was mileage. I don't know why your engine sounds would change unless it's just an affect of the juice under load (again, only guessing).

TC

I echo Bill, other than the cold. Texas summers as well!


Went round and round for well over a year with a Juice/rain (intermittent wipers, in my case) issue. Several Juice versions, boxes; all did it.


Were you running wipers when you noticed the noise?


FWIW, changing wiper control module fixed my problem.

Ok, now I can see that all the information I provided was only part of the story http://www.dieselplace.com/forum/smileys/Ouch.gif. Thanks for the reminders guys.


Ok, yes I was using the wipers, but on intermittent. There was not enough rain to justify a constanst wiper except when I was passing another vehicle. Also, I forgot to mention that I was thinking that it might be the Juice control and/or level setting, I did switch between Tow/Haul and normal and paid attention to the engine noises. I have the Tow/Haul setting at Level 2 and the normal at Level 4. There was a minor, but discernable difference in the engine rattle. I kept in Tow/Haul for about 3 miles at one point and noticed that the Trans Temp did drop about 5 degrees, then stabilized.


TheChevyHDMan....


No Smoke at all, either if I did WOT or throttled down some. Peddle response seemed normal, yea it did sound like a rod knock. Yea, the noise did get worse when I "got on it". No I did not smell diesel, but that might not have been possible since I drove with the windows up, I did not smell diesel when I stopped at the truck stop either. EGTs stayed stable between 600-700 degrees

I think it was the pilot injectioin too. I know wiht my truck it turns off when I put my foot in it regardless of RPM. I think the combination of speed and headwind caused the pilot injection to be turned off. My turck will do it at 2K RPM if I give it enough foot. Seems to do that alott.http://www.dieselplace.com/forum/smileys/Big Smile.gif

Bingo!


Prior to figuring out what the root cause was, when I had what you are describing, I had to pull over and shut the engine off. Restart, and back to normal.


Very intermittent. Would sometimes go for weeks without acting up. I had two distinct independent modes of acting up. One involved what you describe, and would last for extended periods of time. The second involves what Bill described, and would only last for a few seconds; it would either go away, or the motor would die, and I would either have to re-start at highway speed, or coast to the side. It is a good thing it only lasted a few seconds, as it sounded like the motor was grenading big time!


As I said, in my case, changing wiper control module solved my problem.


Feel free to pm me if you want to compare notes further, or to discuss the solution.