This past weekend I towed a boat through the mountains of western Va and Tenn about 700 miles each way. My load was about 15k lbs, and a lot of wind drag.

I have pulled this much before, although probably not as much windage.

I noticed on long grades I would get a "miss" from the engine. it was not a steady misfire like a gas engine with a bad spark plug wire. Less steady of a miss. duuuu......duuuuu.....duu...duuuuuuu......du..du.. .duuuuuu ( if this makes sense )

I had my Edge on 2, which is what I always run it on, and have always towed with it set on. I noticed if I could keep my rpm's above 2k it was better but not totally gone. I switched it to 1 and it was better, but still there. I had plenty of power, I could pull any hill as fast as I was comfortable. But had to baby the throttle to keep this miss at a minimum.

Happened at all boost levels, if I was hard on the throttle I could easily peg my gauge at 35psi, Egt's stayed pretty level at around 1,000 on long grades.

I did notice on the return trip, my fuel pressure has dropped to 12 under a load. So a belt driven pump in on the agenda. But I had almost 20psi all the way on the way down.

Engine did not make any funny noises, could only feel the miss, tach didn't drop or jump. On the way down, engine would run a bit hot on long grades (usually always runs 190, would go up to about 220 for short periods, but would come back down fast) On the way back weather was cooler and I never had temp go up at all. Never lost any coolant either.

Any Ideas? Fuel miss? Lean? timing? Head gasket?

 

my guess would be a fuel problem

 

But higher revs, lower gear helped the issue. And on the way down my fuel pressure was 20psi+/-

So not a supply problem, injector problem? What would be the fix?

 

Might be the beginning of the VP electronics going out. Under a load there's added strain which may cause this. I'd check/replace all fuel filters first and lift pump.

 

APPS?

Did it do it when cruise set?

 

I am getting a new lift pump, going with the glacier diesel belt driven pump. Should have it next week I hope.
The fuel filter was new at the beginning of the trip, but could be an issue if I got a bad batch of fuel I suppose.

I did not use cruise while I was towing. What would that have told me if I had?

Is that something I should try adjusting or just replace it?

 

Yea agree....do a search for "apps reset" and eliminate that as a suspect....it's easy to do and only take 10min. Another thing to check is the crank position sensor by the starter. Check codes CEL to narrow your search.

 

The APPS, if it is acting up, will smooth out the throttle when the cruise is on.

Mine had a low speed "miss" and I would blame it on fuel til I started seeing some apps threads and when I checked it with the cruise set it would disappear.

Just a thought...

 

I will check the APPS, have 120k miles and have never checked or adjusted it at all. Could be the problem.

 

If it is your APPS, for heavens sake buy a Timbo APPS, not a stocker. If you are unsure what a Timbo APPS is, search on it or ask and we will explain.