Given:
TBI to MPFI changes.
16197427 PCM BHMH,
1995 GMC heavy duty 7.4 liter
Thorley Tri-Y header, with Gibson 3 inch single exhaust
K&N FIPK air intake
Edelbrock MPFI, 36 lb/hr injectors
604999 edelbrock performer high compression O-type heads, mild clean up port work, 9.2:1 comp
Rebuild block/bottom end:
Flat top pistons (vs stock dished pistons) (9.2:1
Machined for a roller camshaft
Comp Cams Xtreme roller cam, mild grind, roller lifters, roller rockers
http://www.compcams.com/Company/CC/cam- ... d=441&sb=2
Hardware changes Made:
PCM 16197427 BHMH
Change 1-shorting current sense resistors
Change 2- Jumpering memcal pin 3 to 6
RESULTS:
Tested after these changes and no check engine lights or error codes on the hand scanner and I did not thoroughly test it without further TBI to MPFI flag or constant changes to BIN file
BIN File changes
Prom reader/writer/emulator/data logger Equipment used is Moates APU1 with G2 adapter, emulator cable, and some homemade adapters to read the chips on the memcal (Hard to remove the chips because of interference with Knock retard board)
TunerPro data files used
$31 16197427
16156930 31.xdf
V5 ONLY -31_tpv5_v250.xdf
31.ads
V5 ONLY -
A219_0E_31_v250.adx
A220_0E_31_Trans1_v250.adx
A220_0E_31_Trans2_v250.adx
95 C/K Truck/Van 5.7/7.4L
95/96 Hummer H1 (Gas)
Stock/Edelbrock supplied BIN mask ID is $31 (edelbrock supplied Bin file)
Downloaded TunerPro XDF file from tuner pro -31_tpv5_v250.xdf
Downloaded TunerPro ADX file A220_0E_31_Trans2_v250.adx
Downloaded Edelbrock BIN 1389
Made the below flag and constants changes to BIN 1389as suggested in both the XDF file hack notes and as per a post by "ken at HP tuners" forwarded to me by Fast355 to utilize
http://www.hptuners.com/pub/PFI Memcal Mod.zip
And performed the following BIN changes on a separate chip to preserve the revision history with confidence
Flag changes:
1) Synchronous Fuel at Idle, location 400B-Bit 2, set to “0” for CPI/PFI set to “1” for TBI
2) CPI/PFI Mode, Location 400B-Bit 0, set to “1” for CPI/PFI set to “0” for TBI
3) Use Async Short BPW Offset vs. BPW Table, set to “1” for CPI/PFI set to “0” for TBI
BPW Parameters
4) Minimum Async to Sync ( Or PFI Double Fire) 1.495362 Msec
5) Sync to Async BPW<= 1.296998 Msec
BPW limits
6) ‘AE Max Aysnc or TBI Max Aysnc PW 6.10352 Msec
7) Low BPW Offset vs BPW Table Bias .0305176 Usec
Engine constants
Injector flow rate mpfi 36 lbs/hr9) Injector flow rate mpfi 4.54 gms/sec (calculated from Lbs/hr)
RESULTS:
Tested after these changes and check engine lights was illuminated and I was unable to communicate through the ALDL to check the error code with my hand held scanner.
Idle was at 1500 RPMS both cold and after warm-up complete (195F)
Throttle kicker solenoid was disengaged/de-energized after warmup (No vaccum to kicker)
Bypassed kicker solenoid with vacuum hose direct to kicker, kicker fully drawn in, idle fell to 1200 RPMs, still to high
Reinstalled unmodified “edelbrock” chip in the “TBI mode” and it did NOT have a check engine light on
NOTES
Did not thoroughly test or evaluate any further since I can’t read the faults related to check engine light. I will back out of flag changes one by one and check the “check engine light” illumination. Maybe time to learn emulating and evaluate these changes with burning and swapping chips… I’m nervous tho…
Any ideas? made the suggested changes and they resulted in check engine light and unreadable scanner/aldl port along with the above idle issues
