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Odyssey of the bucking and surging


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Hey guys,

I've been fighting a heavy bucking and surging issue for some time now. My truck is essentially undriveable, and Id appreciate any insight on where to go from here.

 

Symptoms:

Ranging from light to heavy throttle input as long as the engine is under some load, it will develop a violent surge at about 35mph plus. It surges and bucks very badly and on my test drives within a couple miles of my house, its all I can do to nurse it home. It sounds like the footage youve seen of a WWII fighter getting shot down, when it starts to sputter before it catches fire. It idles just fine, and once I get it down to about 20mph it starts to behave again. It seems to worsen when the truck is warmer and the weather is colder.

There are no error codes present.

I believed I had fixed the issue previously, because the #2 injector line was not sealing correctly and air was getting into the line. I discovered a marred crossover tube which was replaced and now all the the lines are bone dry. I had one successful test drive about a week ago, where I went about 5 miles without issue. If I recall, it wasnt super cold that night (40's or thereabouts)

 

Recent repairs and relevant performance modifications:

Industrial injection Silver 62 turbo and II 120hp injectors

Quadzilla Adrenaline Iquad running the stock V2 tune (I have a clue that the timing here could be low for the injectors, its about 13 at idle, and I have not been able to keep my eye on the phone while driving to see what it is at when it starts to miss)

Newish ECM from auto computer specialists

New VP from DAP

All upgraded Battery cables and WT ground mod done

Alternator testing at .03VAC

Timbo APPS

New Cummins MAP and Cam position sensors recently as preventative maintenence

Fuel pressure rock solid (perhaps even a bit high) at 22psi with the fleece dual intank system and fresh fuel filter

Fresh fuel

All ECM VP grounds etc are new and clean I have checked and rechecked power and grounds to the vp and ecm many times.

 

Id greatly appreciate any ideas on what to test next. I miss driving my truck!

Edited by JHFIII
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Most likely need to configure your timing for your engine. 

 

What is your current timing on the Quadzilla. Pay attention to the RPM and the engine load when your load is low and cruise timing is enabled you could possibly be over advancing the timing. It would help if you uploaded your current tune settings or at least post the Max Timing and the other timing parameters so we can see. Yes bucking is cause by too much timing advance.

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There is no way to see the default tune that is shipped. You'll need to create a tune to make it what you need. Not hard nor long to do. 

 

You want roughly, 13° @ 1.5k RPM, 17° @ 2.0k RPM, 21° @ 2.5k RPM, 25° @ 3.0k RPM, 26° MAX for starting. I know this might be too retarded but safer to be retarded than over advanced...

 

Here is what I'm running for my set up. Be aware with the cruise timing high like I run it does buck a bit on low RPM's just drop that to between 2 to 4 degrees on the cruise timing.

Screenshot_20201128-072355_iQuad.jpg

 

Screenshot_20201128-072434_iQuad.jpg

Edited by Mopar1973Man
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Here is a video of how its behaving. This is just driving in my field in circles at 20mph, so in this instance it's at a lower speed than the original post, but it will for certain do this on the road, but rarely driving slowly. Sorry about the angle.

https://youtu.be/Zc4xUhwguho

Edited by JHFIII
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2 minutes ago, Mopar1973Man said:

Disconnect the Quad CANBus connector and see if it goes away if so the Quadzilla is having either power or communication problems. 

Will do. I'll report back. I have no idea what firmware version the unit has right now. I bought it about a year and a half ago. Might have to give that a shot as well 

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My last Quadzilla failure was similar. I found that my ring terminal for ground was lose and created the same problem you had. I've seen one other vehicle with a bad set of red and red/white wires so the Quadzilla wasn't getting good power. Disconnecting the CANbus just stops the Quad from talking to the ECM and VP44. If it straightens out then look into the wiring more so and double check all the connections. 

 

DO NOT hook directly to the battery for either the RED positive or the BLACK ground wires. In the PDC box there is a red wire stud in there to get power. Then hook the black to a the body or engine block it doesn't need to be on the battery at all. 

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Interesting...I havent noticed any funky behavior on the iquad, but that doesn't mean anything.

Btw, I have the power and ground set up like you suggested. Actually, after the wt mod, I made a copper bus bar from the pdc b+ to the unused stud, so now I've got two. The ground is run to a blue seas common ground bar on the fender which is referenced to the body and b-.

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Well, no joy so far. I unplugged the CAN cable from the quadzilla and its still doing the same thing. Worse tonight actually. Always nice when it acts up right by your house instead of 2 miles down the road. Surging under even very little throttle and at idle tonight.

The one thing I did notice is that the thing at idle seems very high. It was 16.5-17deg at idle. I dont know if this makes any difference but when I did my short test drive tonight, I did have the quad on, pl0, with the can unplugged.

Hers a vid of it struggling for idle. This is after I plugged the CAN connector back in so I could get some data logs.

 

 

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6 minutes ago, LorenS said:

Whoah, mine is 13.7ish.

What I dont get is, obviously thats a problem, but is it THE problem since it was misbehaving with the Quad can unplugged? Wouldnt it just default to stock timing?

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16.5 to17 is long term idle tap the throttle it will drop to 12.86 typically. This is normal. 

 

Being the Quad CanBus is unplugged it something else like VP44 to ECM. CanBus is the data line Quad uses so if it unhooked and screwed up yet the the Quad is not to blame. You gave Vp44 or ECM problem.

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11 hours ago, Mopar1973Man said:

You gave Vp44 or ECM problem.

Thats the conclusion that I'm reluctantly coming to as well. Im thinking the ECM the more likely culprit just because the vp is a DAP unit with new PSG. Obviously new parts can be bad though. Looks like I'll have to pop the reman ECM off and send it over to Auto Computer Specialist. As luck would have it, its just past warranty.

10 hours ago, dripley said:

Had you ever run the reman ECM trouble free prior to the issues arising? Or the VP for that matter.

 

No, I technically have not. When I did the ecm repair it was  September last year. I was preparing to move across country, so I just installed it and idled and ran ok just riding around the neighborhood so I turned my attention away from the truck. For the record, the vp wasn't changed out of necessity, I just had an hrvp44 in it that had a lopey idle which I hated. Before the oem ecm went out, I never had a lick of trouble out of the truck.

Edited by JHFIII
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2 hours ago, JHFIII said:

 

No, I technically have not. When I did the ecm repair it was  September last year. I was preparing to move across country, so I just installed it and idled and ran ok just riding around the neighborhood so I turned my attention away from the truck. For the record, the vp wasn't changed out of total necessity, I just had an hrvp44 in it that had a lower idle which I hated. Before the oem ecm went out, I never had a lick of trouble out of the truck.

Same here when my ecm crapped the bed. One day fine and the next pretty much undrivable. Mine surged with mind of its own. But did spit out a lot of codes, none for the ecm. Had it rebuilt and the first one set just one code p0606, ecm failure. Sent it back and worked but just ovrr year wit no cruise. It was a crappy adventure for me. 

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  • 2 weeks later...

I ended up sending out the email to Auto Computer Specialists (where the reman originally came from).

Below are all the faults they found. I have no idea how it even drove at all. Releived they found the problems because I was tearing my hair out, but this was a unit that was about a year and a half old with maybe 40mi worth of driving. 

Strange thing as well was I had 5 volt ref, all gauges working, as well as proper lift pump circuit function.

 

OUR FINDINGS: No Communication to Lift Pump, Lift Pump and APP Circuit in Short, No 5 Volt Reference, No 9.5 Volts and Lose CPU!

 

REPAIRS PERFORMED:

·         Replaced Lift Pump Circuit

·         Replaced Flash Chip

·         Resoldered CPU

·         Replaced APP Circuit

·         Replaced 5 Volt Driver

·         Replaced 9.5 Volt Driver

 

 

Edited by JHFIII
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