dont worry about rewiring tps etc if it looks good in the logs.get it running and get the IAC controlling idle it could be retarding timing to try bring the idle down cause the iac cant.and fit an unmodded ecu and memcal that hasnt been converted for TPI
Thanks for the very good advise. Will remove the jumpers from the sense resistors. Then run the engine and watch to see if IAC sets a fault. Also will see if it will idle down as it should. If all that is successful, then can fine tune the on-idle to near 14.7 AFR on Wide Band.
It is an extraction tool. Here is the adx file.
didn't see this mentioned but when you converted to the 454 TB did you transpose the 2 IAC wires required for the 454 IAC? trying to find my old diagrams from when I switched to a 454 TB and had issues.
87 4Runner, 15" spring lift, 3" body, chevy vortec 355, 5.29 gears, 38.5x15.5x15" Boggers, 280hr, 16168625 running $0D
93 S10, 36x12.5x15 TSL's, custom turbo headers, 266HR cam, p&p vortec heads, $0D Marine MPFI with 8psi boost.
05 Silverado, 2' lift, 4" exhaust, Bully Dog programmer,
Good catch .
Here is the wiring info:
BBC IAC –
Pin A - Lt blu/blk - Coil A Low
Pin B - Lt blu/wht - Coil A High
Pin C - Lt grn/wht - Coil B High
Pin D - Lt grn/blk - Coil B Low
SBC IAC-
Pin A – Lt blu/wht – Coil A High
Pin B – Lt blu/blk – Coil A Low
Pin C – Lt grn/wht – Coil B High
Pin D – Lt grn/blk – Coil B Low
TOM
Last edited by Nasty-Z; 03-27-2015 at 07:48 PM.
1994 3500 Dually , 502 (509) , 264HR , Edelbrock MPFI , PFI '7427
1992 S-10 434 SBC/Tremec - '7427
1986 Monte Carlo SS
1984 S-10 , SAS, 496/700R4/205 , D44/14BFF -'7427
1980 Z-28 496/700R4
1979 Corvette 496/700R4
1977 Olds 98 Regency 403/700R4
First I have to thank you for the kind response. The folks on this forum are fantastic. Everybody, keep up the good work. The harness on the engine run-in stand, was fabricated by Howell for the 454 TBI system using a 16197427 ECU. No alterations have been made to the harness with exception of putting dummy resistor in place of knock sensor to settle some radiated interference to the knock sensor input. Yet, thanks for the heads up as to the differences between IAC wiring differences between 7.4L and 5.7L throttle bodies. The 5.7L uses a square 4 pin connector, whereas the 7.4L uses a oval shaped in-line connector. Am contemplating having additional in-line connector for IAC interchange connections between the two different throttle bodies. Need to do this on the '95 pickup, as the factory harness has the square 4 pin connector that needs to be changed to the oval connector to use the 7.4L higher air flow throttle body.
With the engine idling faster than what is commanded, the ecm is going to bottom out the IAC. The ecm is also going to retard the timing trying to slow the RPM as delcowizzid stated. Have you found any more vacuum leaks? I just disabled knock, egr, and ccp in this bin. I also pulled 35% from the entire Idle VE table. Load this in your APU1 or burn to a chip after warming the engine up. Datalog and post the results. Most of your BLM's from the last log I looked at were at 90. This should help. I assume no responsibility from the use of this file. I recommend you look at the file and do a bin compare in TUnerPro to see what I changed.
Brian
Cannot say enough good words for all your help. Will try the modified BJYL binary. Picked BJYL as there was a comment I picked up that this is the binary for export Vortec TBI. If this is not proper, just let me know. Just checked the four wires from the distributor to the ECU. They are good. Also replaced the module in the distributor. Will search for more vacuum leaks. For the first time will try to do a bin compare. Thanks again.
BJYL is a calibration (binary) for a 1995 5.7 TBI engine, auto transmission (4L60E) with a 3.08 rear axle ratio. It isn't for Vortec and is not export. Most export bins are not closed loop because they don't use an oxygen sensor. They don't use the oxygen sensor because of Leaded gasoline. BJYL is a good calibration to start with.
Riscard, I haven't seen anyone ask this question, so I figured I ought to. Are you using your wideband O2 sensor in place of the narrow band sensor as an input to the 7427?
Square body stepsides forever!!!
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