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duxthe1 · #21 10-26-2019, 12:21 AM

Early update, but its worth it.

First off I enabled the secondary block of code that uses the same trim resistor enable byte. Test drive didn't reveal anything out of the ordinary, in terms of EHA current or overall driveability. That chip comes back out to be blanked and rewritten.

Next I decided try some other trim resistor values. Figured that even though I didn't start at the beginning I might as well go back to the beginning. The lowest value resistor in any of the charts is 487 ohm. Wrote its value into the appropriate register and took a test drive. I noted moderately more warmup enrichment than stock that tapered off by 60C. Pretty cool, but not what I'm after. The next value in line is the 953 ohm resistor, already tested and determined to give a lot of warmup enrichment tapering off at 80C.

The next value in line is 1270 ohms. The test drive with this value loaded gave a pretty good payoff.

This setting re-enabled WOT enrichment, which my CIS module previously did not have in any form. I have my EHA set where my closed loop current runs in a range of ~0 to -10mA with a mean average around -5mA.. Now when I hit the full throttle switch I get +2.5 to +3mA of current that ramps to over +6mA as RPM climbs. My EHA current monitor screen updates every 1/4 second and I noticed once when I punched it, that I momentarily caught a +60 mA reading. I only noticed it once in several WOT stabs, so it was either a fluke or there is also a very quick large shot of EHA current that only lasts a few milliseconds as the full load switch closes.

I also tried stabbing the throttle several times without closing the full load switch, aiming for 80-90% throttle. It was obvious that the enrichment doesn't kick in without the full load throttle switch closed. Now I'm not gonna say that 10-15mA worth of EHA current is life changing, but it is noticeable. If anyone is reading this that isn't familiar with the car, it has had a bit of work done in the head along with a longer duration intake cam. MY motivation for this endeavor was getting better fueling to complement the mods to the engine.

I could stop here and call it done, and be happy with my results.

Y'all should know that's not my style. I've still got 4 other resistor values to try. (after I finagle enough UV to blank my collection of chips) Barring any of the other resistor values having better results, I need to see if I can dissect the code that gave the enrichment and see if I can tweak it from there. Another consideration is that the 965 and 966 code is slightly different, 94 bytes different to be exact. After I get more blanked chips, (I'm out at the moment) I'm gonna mod the 966 code to see if it responds any differently. It didn't have WOT enrichment either and the major differences reside in data blocks and not code blocks.

Regardless, I now have a legitimately "chipped" 55pin CIS ECU!