Wrong Mask for PCM?

**350yj** · 12-02-2015

Hello,

I have been off and on with tuning my engine. I wanted more power out of it, so I rebuilt the top end with this Summit Racing Kit: http://www.summitracing.com/parts/sme-k-355-400

The engine is a 1987 350 cid out of a K1500. The ECM that I am using is out of the matching vehicle and the PROM has a sticker with "ACSN" covering the erase hole. My question is, am I using the correct files in TunerPro? The engine seems to want a lot of timing to run happily. I am close to the mechanical limit of the distributor at the top end of the table (3600 rpm).

BCC Lookup gave me the following information:

BCC: ACSN
Year: 1987
Release Date: 31576
Eprom: 16069997
ECM: 1227747
Prom ID: 9998
Scan ID: 881
Platform: R2
Engine: L05
Displacement: 5.7
Trans: M20
Trans Type: MAN

With that, I am using the ASDX 88 C-K bin file, $42-1227747 XDF file, and $42-1227747-V5 ADX file. When reading the stock chip, the timing table is all zeros. Should I be concerned with this?

Kris

**1project2many** · 12-02-2015

The main timing tables should not be all zeros. Maybe you got a bad read from the chip, or maybe the chip is faulty. Or maybe you're loading an ADX and not also loading the XDF file?

There is an ACSM here: http://www.gearhead-efi.com/gearhead-efi/bin/ You could load that one up and look it over to get an idea of what your calibration might look like.

**350yj** · 12-03-2015

That was ACSM not ACSN. Is there a big difference? I looked everywhere for a stock ACSN bin and was unable to find one.

I have the Moates APU1 kit. Re-reading my ACSN chip never passes the 'Verify Chip w/ Buffer' option. This may be a bug because I get the same result with a Jet Stage 2 chip I also have that Jet said matched the ACSN PROM.

My question is, are the verification failures a red herring? I have looked and cannot find an ADX or XDF file to go with the ACSN bin that I have. This may be what is causing strange timing/fuel numbers.

Should I ignore all of that and start with a fresh bin? If so, which one should I go with?

Kris

**1project2many** · 12-03-2015

I haven't looked at the differences but what I'm suggesting is that you make sure you can see spark numbers and other values with the known good file ACSM. If all you see are zeroes then you have something wrong with your tunerpro configuration. You should be using $42 definitions. If you can "Read" ACSM in Tunerpro then you probably have something wrong with the file you read from the chip and need to check your configuration for the APU1.

**350yj** · 12-03-2015

Makes sense, the ACSM file appears to have the same spark values as the ASDX file in TunerPro. I verified the switches on the APU1 and the TunerPro configuration. I did have the chip positioned incorrectly in the reader, however putting it in the correct spot made no difference to what I am seeing the timing and fuel tables.

Edit:

Added my read of the ACSN chip.