05 cummins tuning

got a 05 cummins 48re muldoons fmvb 1000hp trans, s&s 100% sac injectors, S&S 12mm cp3, fass 290 stock turbo. ive got issues where my truck will surge hard when accelerating a bit between 1300-2000 rpm. the frp fluctuates between 13000 and 17000 psi during that time. this issue happens mostly when i have the tc unlocked. sometimes when this surging gets real bad, i can let off the throttle and the truck will continue accelerating while surging untill 2000rpm or i downshift. ive got the attached log and tune files.

another thing id like to figure out is how to get the reverse lights and prnd21 lights to work. Park light goes on when im in park or nuteral but id like all the lights to work correctly. id like the reverse lights to work so that i dont have issues with people not seeing that i want to back up etc.
thanks

Good luck getting tune help on here . For the reverse lights u can wire them up to a switch .

Timing issue

look at FCA duty cycle and fca current, figure out where it is surging and add to the DC to current table. when adding current makes the cp3 work less and wont overwhelm the fca

Timing is likely too low where the turbo is surging

His rail pressure is fluctuating thats causing the surge..

play with DC to current and/or base DC tables.....and reduce timing at cruising area.......and idle area.....0 to 3 at idle and 5 to 8 while cruising is enough

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Originally Posted by MAIDENCR

play with DC to current and/or base DC tables.....and reduce timing at cruising area.......and idle area.....0 to 3 at idle and 5 to 8 while cruising is enough

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This ^

My experience has been combustion too late in the cycle that pushes the turbo past its surge line thus surging and low timing was the culprit and everything else happening during surging was a byproduct of that. Not once have I ever heard of rail pressure cause a turbo to push past its surge line, makes no sense. But what do I know besides my experience.

But he have a big pump and still use mostly stock fca dc table....this will make rail surging....and he have 13? of timing at 1500rpm....way too advanced

Quote:

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Originally Posted by Jim P 2.0

My experience has been combustion too late in the cycle that pushes the turbo past its surge line thus surging and low timing was the culprit and everything else happening during surging was a byproduct of that. Not once have I ever heard of rail pressure cause a turbo to push past its surge line, makes no sense. But what do I know besides my experience.

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Never had that issue with tuning an engine with a bigger pump and bigger injectors. Never looked at the tune but 13 degrees of timing at 1300rpm and what? That’s not enough information or enough of what goes into injection timing. There is fuel quantity to factor in, there is still duration from pressure to factor in. Before going and pissing around with fine intricate stuff, start with basics. Stock tune and go from there. Does anyone realize when a turbo starts surging while trying to accelerate it’s chopping through air, messing up air flow into the engine, creating choppy air flow into the engine that subsequently causes erratic engine behaviour, choppy everything? That’s assuming he is experiencing surging and not the engine trying to roll backwards from too early of ignition in the cycle where the combustion is fighting against the rotation of the engine. My experience with legitimate turbo surge while trying to accelerate was injection timing, lower rpm and higher fuel quantity demand and timing too low and caused erratic behaviour in everything in the window the turbo surge was happening and that was on a truck with a 12mm injection pump, large injectors, etc etc. and I didn’t have to start pissing with FCA current. Basics of good desired rail pressure, good timing and good pulsewidth table for the size of injectors for the airflow being produced is the start of a solid foundation of a good tune before fine detailing of things like FCA current in my opinion. Any of those 3 items aren’t right it can cascade into other things and make it appear to be caused by something else, seen it many many times over.

Even if it’s a combination of pulsewidth, rail pressure and timing that needs to be changed, a combustion event carrying too far down into the downstroke of the cylinder cycle is going to result in excessive drive pressure to the turbo and push it past the surge line, chopping air, choppy air equals airflow getting cut on and off into the engine equals choppy engine behaviour. Logic paths.

When it surge timing is 13? for like 600us at like 1500rpm....its too advanced...its not causing the surge but it still too advanced...the issue is rail pressure im 98% sure of that

Possible timing is too high, but again more to it and surge comes from high drive pressure on the turbo. Combustion fighting back against engine rotation is not surge if that’s what’s happening and will have a similar effect and just goes back to what I initially said, timing issue. Fix where the combustion cycle is happening and 100 percent things will sort themselves out. Start at the beginning, not the end, begin with the basics not the advanced. I’ve never had to mess with FCA on the 3rd gen 05-07 with large pumps and injectors unless trying to squeeze every bit out of it possible. Begin with a proper pulsewidth table for the injector size being used, a good rail pressure table and a good timing table for a starting base and there shouldn’t be any issues, but what do I know, only been doing it for 12 years.

Troubleshooting starts at the beginning. Plug a corded drill and pull the trigger and it doesn’t do anything, you just start tearing the drill apart to figure out what’s wrong with it? No, you start at the beginning and check to see if you even have power. I’ve seen people stare at a program from machinery for hours trying to figure out what’s wrong for this most basic of things where they should have started at, checking for power.

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