Need to Learn Tuning 101 Quick!

[Mphiver]

Hi,
I am new to the Tuning DIY world and have decided to leap in with both feet! I have purchased the Moates AUD1 kit and GX2/EX multi-program stacker for my 1614299 ECU.

A bit of history: 1992 GMC K1500 P/U with highly modified 383 SBC (was original 5.7L, stroked); Edelbrock alum heads, small chamber; 8.1:1 C/R; Whipple supercharger with 454 TBI, 75# injectors. Dave Darge of Powertrain Electronics originally tuned it by burning an EPROM and the truck was turn key for years, passing smog in Cali every 2 years like clockwork. Somewhere as it aged, it would not pass smog and I let it sit. Preparing to move to Prescott, AZ where there is no smog requirements, I went through the setup to get it running again.

Things I found and fixed: One or both fuel injectors were dumping fuel erratically; I rebuilt the TB and replaced the injectors and had it bench tested and verified; I had the supercharger rebuilt, seals and bearings, rotors timed; I replaced the distributor with the GM Performance OE model; Replaced plugs, wires, O2 sensor, MAP sensor, TPS sensor. Compression test, fuel pressure, etc. all good.

This setup uses the factory fuel pressure regulator up to zero manifold pressure and an auxiliary multi-stage fuel pressure regulator takes over in a linear fashion as boost pressure increased... sent that to Dave Darge and had him install a new diaphragm kit and set it up again (not complicated, various spring tensions can be swapped to change the response to boost pressure).

The problem: After all this work, the engine fired up cold fine and idled down smoothly while I went through the ignition timing procedure (zero degrees with Electronic advance wire disconnected). Test drive was as it always had run right up until getting into positive/boost and power dropped off 20-30%... just no power at WOT.

I have pulled my hair out trying to find any reason why this turd wouldn't run as it used to and what I may have done wrong or overlooked in my cleanup work. I looked for vacuum leaks, none idles at -15psi (supercharger turning). I looked for fuel pressure curve as boost increased by attaching a fuel pressure gauge to my windshield and going for a drive; sent a video of that to Dave Darge and he said it was fine! Ramps up to over 40psi at 5.5psi boost. JUST PISSING ME OFF!

Further problem: NO ONE will help me with an old school OBD1 highly modified forced induction engine running TBI!!! Enter the Moates group.. I am no obsessed with learning and understanding the tuning process and able to make tuning adjustments independent of the Dyno shops.

I think I have an option to share data logged info and BIN files with Dave Darge as he is not fully retired yet but he is a long way away to deal with him personally! HELP!!

I am at the stage where i have 'read' the Powertrain d2732a chip into my Autoprom, stored it as a BIN file, Burned it to one of my new 27SF512 chips at the top address in the stack for multi-tunes. I am now soldering in the G2X adapter onto my ECU board and (fingers crossed) I don't screw that up, I will be installing the ECU back into the truck and attempting to start it with the "Original" PowerTrain tuning BIN.

Can any of you recommend a proper XDF file for my 16146299 ECU... I am assuming I will find NO BIN files close to my setup. Do I need an ADX or ADS file or does the XDF file accomplish everything TunerPro RT requires?

Thanks in advance for any and all help!!
Mark

[Mphiver]

-- forgot to mention, this truck has a 700r4 trans and the $99 XDF seems to reference a 4L60E electronic trans?? Want to find the correct XDF for my ECU?!

[In-Tech]

Hello,
As you and Dave and I know, unless something mechanically changed in the engine, there is no reason to alter the eprom. I am assuming this is a 3 port regulator? The fuel pressure in your application should ramp up from ~13psi stock to ~25psi at WOT at your boost level.

Based on experience I suspect your "new" injectors. I have seen many replacement tbi injectors work fine at stock fuel pressure and fail horribly under higher pressure(stick closed) The fact that your fuel pressure is 40psi kinda tells us that you have no fuel flow unless there is a problem with the regulator(doubtful).

The 99 ecu cannot control the trans except for TCC lockup. The xdf must be improperly labeled. I believe GM called them 4L60 when they went to electronically controlled lockup torque convertor instead of 700r4.

[WASyL]

Listen to what engine wants, avoid knock and get WBO2. that is true 101 of tuning.

[sherlock9c1]

Greg Banish has some great books on tuning. Agreed with above - fix the fueling first, then play with timing, then revise the fuel one more time and you'll be good.

[1project2many]

Hi Mark,

I would also suspect the injectors are not delivering sufficient fuel. Whether they are faulty or not they might not be able to operate properly with that much fuel pressure. Oscilliscope curves of the injector opening and closing could help determine whether or not they are the problem.