ECT.c & IAT.c malfunctioning

[mattsmallen]

Hello. My ECT.c and IAT.c act erratically during warm up and while driving as shown on this data log. My engine is a H22a4 with a P28 ecu. It seems to be causing wild swings in my AF ratio and ignition timing. What would cause this to happen?

ps my sn is 37892. Relevant modifications are PLX wideband into D10 (R136 & R138 removed) grounded to G101 (thermostat housing), IAB removed, EVAP removed (no purge cotrol, can vent valve, fuel tank pressure sensor), EGR removed, stock O2 #1 removed, cat removed, intake control valve removed, OBD1 distributor with TDC & CKP sensors bypassing stock sensors. That's all I can think of for now.

[mattsmallen]

I just realized that because I have no cat, I do not need fuel enrichment during warm up, so I zeroed all the water temperature compensation figures in the fuel compensation parameters, except for "Minimum compensation - load based" at the bottom because I do not know what that is. I uploaded the calibration before starting the car totally cold and let it run for a few minutes before starting the datalog. Under these circumstances the ECT.c behavior was interesting. It stays at zero until the throttle is engaged, then after a two or three second delay it wildly spikes as much as 20% then drops after a couple seconds. 22% throttle gets a 20% ECT.c spike, 5% throttle gets a 4% spike, so at lease there is some science going on somewhere, but I am not smart enough to figure it out. The IAT.c just randomly spasms non-stop between 0 and 5% with no perceptible correlation to the air temperature readings.

It's a great project you guys have going on though and a great product. Very cool. And thank you for all the time you spend helping us out on this forum. I've learned a tremendous amount from it and the rest of your website.

[Spunkster]

You still have a 20% correction on ECT fuel for load and since the engine is still cold it is adding fuel as soon as load is applied.