Very unusual '7747 .bin ~ 7.4 liter / 700R4

[dave w]

Mark,
That's about the same write up I gave the customer. His comment was "Fix It". The customer has a modest budget, so fix it I will! I'll post back with what I end up doing. For the time being, I'm going to disable EGR, disable ESC, inspect injectors (maybe some OEM numbers are on the injectors?), check timing, and check, fuel pressure. I'll start with a modified stock tune (7.4 engine parameters / 5.7 liter 700R4 parameters),and go from there. I have a vacuum referened fuel pressure regulator in reserve, if needed to fix the rich idle / lean upper RPM. It's going to be a long weekend.

I've had good results increasing BPW to about 145 on some '7747 applications.

dave w

[EagleMark]

Mark,
That's about the same write up I gave the customer. His comment was "Fix It". The customer has a modest budget, so fix it I will! dave w

Truck does not sound like a modest budget? Maybe funds were mis apprproiated on engine, tires, suspension and gearing and forgot a tune?

Maybe he can cancel a remote location journey to pay and get the truck running? Just one trip at 8 mpg tops would pay for the tune day with me...

You won't find much to be had from a 4lo tune espeasilly this ECM, I can't even see a dyno work in 4lo with 46 inch tires or a dyno owner trying? Those tires would only need 20PSI for the street, drop them down to 10 for a load on data.

I've noticed in some OBDII cals that torque managment really restricts 4lo, probably to save drivelines. Real easy to break any and everything in driveline 4lo... double torque.

[dave w]

Truck does not sound like a modest budget? Maybe funds were mis apprproiated on engine, tires, suspension and gearing and forgot a tune?

Maybe he can cancel a remote location journey to pay and get the truck running? Just one trip at 8 mpg tops would pay for the tune day with me...

You won't find much to be had from a 4lo tune espeasilly this ECM, I can't even see a dyno work in 4lo with 46 inch tires or a dyno owner trying? Those tires would only need 20PSI for the street, drop them down to 10 for a load on data.

This thing is so "over-the-top", it is most likely towed on a flat bed trailer to the play grounds. It's so "over-the-top" ramps to load / unload on a flat bed trailer are optional!

My idea of modest might not be the same as yours. I won't earn a full mortgage payment for my services, but something close.

dave w

[EagleMark]

I thought the modest budget meant he spent all his money and couldn't afford a tune...

How much motor work is done? Your lucky it seems to have the fuel to support WOT to begin with. That is usually overlooked on builds... should actually be easy with this done.

[dave w]

Pics as promised.

dave w

[PJG1173]

yeah thats a big one. not too big though.

[EagleMark]

Oregon Sand Dunes tires!

[1project2many]

"Mystery" bin is ASDU with small changes. Basic stuff... injector constant, max BPW, main spark, main fuel, PE AFR and target idle speed. 317 bytes total.

Edit: As Mark mentioned, cal is out of fuel early on. VE in main table has values 20% to 30% greater than stock. Cal is out of fuel but engine may not be. Injector constant is larger than any stock 7.4 cal which limits fuel. Very large difference... why? Wrong injector size during calculations? Screwed up and assumed later injector flow rated at 12 psi instead of measured 30? Engine obviously swapped in (454 + 700R4 = dead 700R4). Was 350 running on 454 TB and I briefly before larger engine put in?

High spark peak at 1k rpm and idle speeds in the 750 rpm range. Auto trans doesn't typically like high idle. Hopefully that converter is pretty loose, esp. with those tires. Tight converter and high idle plus big drivetrain means engine is constantly fighting to "drive" truck at idle. Bad combination. That would mean high spark plus high idle is just trying to keep engine idling in gear. Much harder to tune. Still doable, use IAC park/neutral adder adder to increase idle speed in drive. OTOH if loose converter then fast spark ramp is good idea. Snap hard as soon as throttle is opened to give "hit" and help get truck moving. But tailor it to match stall speed and back it down if throttle is released and MAP comes back down. "Digital throttle" effect (you know, all off or all on, no in between) is a result of too much spark too soon in too many cells.

I would not change injectors. 30 psi injector does better... better atomization, better burn. That's just me. I don't know how the truck is built but if the engine is near stock with maybe headers and mild cam, converter's loose, and truck isn't street driven very often I'd be looking forward to it as an easy job. Hardest part is connecting DVOM and scope to get "real" readings from the sensors.

Happy tuning.

[dave w]

"Mystery" bin is ASDU with small changes. Basic stuff... injector constant, max BPW, main spark, main fuel, PE AFR and target idle speed. 317 bytes total.

Edit: As Mark mentioned, cal is out of fuel early on. VE in main table has values 20% to 30% greater than stock. Cal is out of fuel but engine may not be. Injector constant is larger than any stock 7.4 cal which limits fuel. Very large difference... why? Wrong injector size during calculations? Screwed up and assumed later injector flow rated at 12 psi instead of measured 30? Engine obviously swapped in (454 + 700R4 = dead 700R4). Was 350 running on 454 TB and I briefly before larger engine put in?

High spark peak at 1k rpm and idle speeds in the 750 rpm range. Auto trans doesn't typically like high idle. Hopefully that converter is pretty loose, esp. with those tires. Tight converter and high idle plus big drivetrain means engine is constantly fighting to "drive" truck at idle. Bad combination. That would mean high spark plus high idle is just trying to keep engine idling in gear. Much harder to tune. Still doable, use IAC park/neutral adder adder to increase idle speed in drive. OTOH if loose converter then fast spark ramp is good idea. Snap hard as soon as throttle is opened to give "hit" and help get truck moving. But tailor it to match stall speed and back it down if throttle is released and MAP comes back down. "Digital throttle" effect (you know, all off or all on, no in between) is a result of too much spark too soon in too many cells.

I would not change injectors. 30 psi injector does better... better atomization, better burn. That's just me. I don't know how the truck is built but if the engine is near stock with maybe headers and mild cam, converter's loose, and truck isn't street driven very often I'd be looking forward to it as an easy job. Hardest part is connecting DVOM and scope to get "real" readings from the sensors.

Happy tuning.

Thanks for the input! I was thinking the mystery .bin was AMUR, similar to ADSU?

There is an aftermarket fuel pump and fuel tank, not sure what the ratings are for the fuel pump inside the gas tank. I think there is a very real possibility the fuel pump might need an upgrade? I can measure pressure, but figuring flow is not something I've done. The local "Dyno Tuner" will not tune a TBI 454 unless the stock fuel pump is upgraded. I'm hoping that the 80 lb. hr. injectors, with stock 12 PSI spring will work out, according to the WBO2.

dave w