Mine drops out sometimes, not always when it's warming up, but it's more common in that phase. Planning on giving the IACV a good clean out to see if that fixes the issue of occasional drop outs when the engine is warm, but as I now have a space ECU I was planning on doing the manual transmission mod too, which got me thinking about the alternative maps and whether there was any more power to be had out by switching.
Chris
Pulling the EFU fuse to reset the ECU before each run would probably be the best approach. At least then the ECU will be starting with the same settings for each run.Originally Posted by bigcw
From memory I think the 3rd resistor controls EGR operation, if you're doing a full throttle dyno run you won't see any difference as the ECU will turn off EGR on full throttle anyway
Cheers, Jon
On engines with a stepper motor IACV the ECU tries to put the IACV back to startup position when the ignition is turned off. I haven't checked (as I don't have a Camry anymore) but the ECU will probably stay powered on for a few seconds after igniton is turned off.
If the wiring for the engine swap in to the MR2 cuts power as soon at ignition is turned off then when the engine is next started the ECU will think the IACV is in the correct position but in fact it's in the hot idle position. On a cold engine this will cause the engine to cut out if the throttle is closed.
Cheers, Jon
That only applies to ECU's equipped with an Mrel pin for controlling the main relay, as far as i've ever been aware the 3vz ECU does not have Mrel.If the wiring for the engine swap in to the MR2 cuts power as soon at ignition is turned off then when the engine is next started the ECU will think the IACV is in the correct position but in fact it's in the hot idle position. On a cold engine this will cause the engine to cut out if the throttle is closed.
I may stand corrected, the USDM wiring diagram shows Mrel on pin 3D on the 3vz-fe... i don't know if a UK 3vz has this pin but i'll be looking tomorrow, could be something to investigate.
Ah, I was just going to say the ECU wiring diagrams I have (probably USDM) have M-REL on pin 3D.
Sounds like we may be on to something interesting here! I assume 'm-rel' feeds a live to the main relay after the ignition is switched off then cuts it as soon as the ECU has finished resetting everything back to the startup point?
Also, back to my original question, is anyone interested in seeing comparative graphs with the AT/MT and map resistors changed or am I wasting my time?
Chris
I'd certainly be interested. I have a couple of AUSDM 3VZ-FE ECUs (one is a modded A/T ECU, the other a genuine M/T ECU) that I could probably lend to you if you would like to do a comparision. The M/T ECU is on loan to me so I'd first need to check if it would be OK to lend out.
Cheers, Jon
I would like to see comparative graphs, I also have a late model ADM manual ECU, I also have a 96 camry in the driveway that I could use to check the IACV operation, as far as I can remember you can actually hear it click shut when you turn off the ignition so maybe Jon is on to something
In the next couple of days I will get my multimeter onto pin 3D of the ECU and see if it does indeed supply power for a few seconds after shutdown
If Mrel is present then that's what it will do, it's an output so will always work wether it's connected or not.
However i wouldn't place too much importance on Mrel, we don't use it on the 1mz or 2gr swaps (it actually causes more problems) and both of those engines never drop out when idling, so i personally don't think Mrel is the answer.
If you look at owners who have fitted manual ECU's from the US, they don't stall at all and that is WITHOUT Mrel connected, leading me to think it has always been an Auto ECU input that is causing the ECU to temporarily "let go" of the ISCV.
We have a mod that cures it though albeit crude.
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