Engine/Transmission (1998.5 - 2002) Update one bucking issue after rv275s and ez tuner

[woodtrucker]

I thought I'd update the few of you that have responded to my issues after installing the 275's.
Originally, i had a bully dog torque dog. Swapped that out for edge ez and it was a good upgrade. No fueling issues.
Added the rv275's and notice some bucking especially on level 3 on tuner.
Mod's were done in november and I had a suspicion that the bucking was ambient temp related after driving on some warmer days versus cold and some forum reads.
Today was a great day to check things out again. 44 this morning and 70 now. This morning I noticed the bucking as usual. Out for lunch today and it seems to fuel much better.
Some forums have mentioned the vp44 24v's with performance mods not playing well in cold weather.
Can anybody provide a somewhat scientific reason for this? I'd love to know. Or if someone thinks I have a serious issue, please chime in! Whoo-hoo! 70 degrees! I'll take it!

 

[RustyJC]

Where do you experience the bucking? At very low load conditions like idling along or with very light throttle applications at a constant speed in 1st gear? If so, I had the same experience with DD2 injectors and an Edge EZ on my 2002 ETH/DEE 3500 that dynoed 347/762 uncorrected at the rear wheels on a Dynojet. It's a phenomenon of the larger injectors. The governor function of the VP44 is trying to maintain a constant engine speed based on throttle position. If the engine speed drops, the VP44's "brain" sends a command to give the engine X more fuel to bring the engine speed back up, but the bigger injectors will deliver 1.5X (for illustration) more fuel - therefore, the engine speed will overshoot the commanded value. In response, the governor function will give a command to cut Y amount of fuel to bring the speed back to desired value, but the bigger injectors will cut 1.5Y amount of fuel, so the engine speed will undershoot. And it will continue in this overshoot/undershoot cycle until more throttle is applied or you clutch it and let it settle back to unloaded idle. It sorta sounds like a 60's musclecar idling along with a long duration, high lift camshaft. I really didn't experience it as much when towing our 5th wheel RV under these conditions because the load on the engine was higher and the weight of the RV damped out the increase/decrease in road speed. I finally grew used to it and just accepted it as a characteristic of a "bombed" truck.

If you're familiar with control systems, the larger injectors increase the gain in this closed loop system. The surging is an excessive gain cycling event.

If your surging is happening higher up in the load range, ignore the above....

Rusty

 

[woodtrucker]

Thanks for sharing that insight. It's happening only in the low rpm bands of 5th and 6th gear.
Nowhere else really. And i tried several times to male it happen coming back from lunch in warm weather and its running like a champion right now! Might still have something to do with what you stated above though?!?!?. I'm headed to MB, SC for a few days at end of april, so I'm gonna take camper on a short interstate test run later this month to be sure the problem isnt worse when towing. I expect if temps are in 60-70's I will not experience a single issue.

 

[klcammie]

I run rv 275's but no edge or any other box, and do not have the issue you are having. Regardless of the temp. Try unhooking the edge and running without it. There could be a problem with it. Also check your intake air temp. sensor if there is a problem with it reading cold temps it might retard timing to much then the edge is trying to advance the timing.

 

[woodtrucker]

Great tip. Thanks!

 

[VolsFan]

I run rv 275's but no edge or any other box, and do not have the issue you are having. Regardless of the temp. Try unhooking the edge and running without it. There could be a problem with it. Also check your intake air temp. sensor if there is a problem with it reading cold temps it might retard timing to much then the edge is trying to advance the timing.

I just recently installed an EZ on my rig as well, also with the 275s. I've had a handful of different boxes, and none of them have this surge like the EZ does. It only does it when I'm really getting on it pushing 30+ psi boost. I'll have to check the IAT sensor.

 

[SnoKing]

I ran a edge comp in the EZ mode and Jammer 1 (Stage 1) injectors for years without issues with both stock HY35 turbo and a PDR35-12W turbo. Snoking

 

[woodtrucker]

Update on my bucking issue:
Anytime I'm traveling loaded or unloaded at 55 degrees or higher, I have absolutely none of these bucking symptoms. Very strange but the truck runs like a top now that we are in warm spring weather. I wanted to be certain so I intentionally drove it on some colder days and the bucking issue came back so I know it's ambient temperature related.
I even towed to Myrtle Beach and back and running EZ on level 2 pulling fancy gap, I didn't have to down shift until about halfway up the mountain when EGTs got to about 1150. I topped the mountain about 55 mph so I was very happy towing about 9k lbs. No hesitation or bucking whatsoever. I have not checked out the IAT sensor yet. Still need to do that.

 

[Regcabguy]

I run rv 275's but no edge or any other box, and do not have the issue you are having. Regardless of the temp. Try unhooking the edge and running without it. There could be a problem with it. Also check your intake air temp. sensor if there is a problem with it reading cold temps it might retard timing to much then the edge is trying to advance the timing.

My '98.5 had Mach 1 85 hp injectors and was a hot running dog. I added an Edge EZ with boost elbow and it was a freight train.
As predicted this required a DTT trans upgrade.