This is a FWD 3400 with the 7730 ECU, $A1 code mask, and BFUZ bin (92-94 alum head FWD manual v6 ) using Ostrich 2.

When I start the motor and let it idle @ 0 TPS and 0 MPH, the idle runs around 1800-1900 rpm, while the requested idle RPM is around 900rpm. The IAC value seems to hover around 50...i would think such a large discrepancy would cause the IAC to drop to 0. Additionally, IAC malfunction code 35 is not being thrown, despite the RPM difference being off by (a lot) more than 250 RPM. I verified the flags are enabled.

This is a stock 3.1L BIN. I also tried a 6D bin and have the same problem. Is it possible that there is a faulty sensor or something else, and the reported RPM in the ALDL datastream is different from the one used in calculations to command the idle speed?

If it helps in the diagnosis, someone on another forum pointed out that the idle speed appears to be consistently double the requested speed. Also its strange to me that a stock tune for a 3.1 L would off the shelf be way too rich for a 3400.

I have attached the log in CSV and tunerpro XDL.

Thanks in advance!

 

So I am fairly certain I found the problem: I had a fuel pressure gauge installed and the nut started to leak fuel. Removing the gauge from the Schrader valve brought the idle to within range. I have no clue why the computer was compensating the way it did and not throwing codes