7427 data logs closed loop issue

[Parts]

Hello everyone,
I have a 5.7 TBI from a 92 G20 van in an S10 with a 4l60e. I rewired the harness for a 7427 computer, the computer is running the stock tune. The truck runs well in open loop, but when closed loop activates the RPMS at idle bounce around, runs rough, and eventually stalls. I used tunerpro RT with Advanced $0D TP5 v251 XDF and A217 $0D TP5 v250 ADX to take these logs. I have attached 2 data logs, one just idling, and one with a few stabs of the gas pedal. Any help would be greatly appreciated!

[mecanicus]

Hello,
i guess your idle-gas is too lean so the IAC has to compensate this, that engine will not stall.Try attached xdl and adx files!

[dave w]

Hello everyone,
I have a 5.7 TBI from a 92 G20 van in an S10 with a 4l60e. I rewired the harness for a 7427 computer, the computer is running the stock tune. The truck runs well in open loop, but when closed loop activates the RPMS at idle bounce around, runs rough, and eventually stalls. I used tunerpro RT with Advanced $0D TP5 v251 XDF and A217 $0D TP5 v250 ADX to take these logs. I have attached 2 data logs, one just idling, and one with a few stabs of the gas pedal. Any help would be greatly appreciated!

It's running rich. Try changing the injector flow to a higher flow rate to lean things out. For example change the injector flow rate from 61 lb / hr to 64 lb / hr. Increasing the injector flow rate will cause the PCM to "think" less fuel is needed for all RPM's and Kpa's.

Gearhead Post 12-31-23.jpg

[dave w]

Hello,
i guess your idle-gas is too lean so the IAC has to compensate this, that engine will not stall.Try attached xdl and adx files!

The 4L60E uses definitions $E6 and $OD.

The 4L80E uses definitions $OE and $31.

[Parts]

Thanks for the tip. One more question, just did the SST 27SF512 mod. I soldered this in backwards didn't I?PXL_20240101_201801048.jpg

[dave w]

Thanks for the tip. One more question, just did the SST 27SF512 mod. I soldered this in backwards didn't I?PXL_20240101_201801048.jpg

Unfortunately, you are correct, the 27SF512 Chip is backwards.

[mecanicus]

It's running rich. Try changing the injector flow to a higher flow rate to lean things out. For example change the injector flow rate from 61 lb / hr to 64 lb / hr. Increasing the injector flow rate will cause the PCM to "think" less fuel is needed for all RPM's and Kpa's.

Gearhead Post 12-31-23.jpg

Hi Dave,off course you are right, BLM near idle is always under 128. So wouldn`t it be better to change the VE Table?

[dave w]

Hi Dave,off course you are right, BLM near idle is always under 128. So wouldn`t it be better to change the VE Table?

The posted data logs were insufficient, only open loop with about 3000 recorded data points.

Typically adjusting injector flow rate that has some cells lean and some cells rich is a good plan for VE tuning.

Typically, 30,000 or more closed loop recorded data points is required for adequate VE tuning.

[Parts]

Thanks for the help everyone! Right now I am trying to get it to idle in the driveway before I go on a drive. I am going to take a crack at the VE tables once I can drive and have enough data. I'm sure I will have more questions. Thanks again!