Chasing long time problem.
ZZ4 / HSR / 730 / 8D / aftermarket harness has been running perfectly for 12+ years.
6 months ago started running rough when stopped at lights and sys light came on.
Shows DTC 43
Following 3rd Gen recommendations EVERYTHING , in the system has been replaced with new or known good including a different ECM and a different tune.
All wiring segregated.
Unable to fix problem ,currently have the resistor on the KS circuit.( resistor can be seen from ECM plug - to conform wiring good.)
As soon as engine starts ,it puts up the code , but there are no KC showing ?
As soon as engine starts , it retards spark as shown but when revs raised @1500 rpm ,spark retard goes to zero until it returns back to idle.
Engine is closed loop , stable 700-750 rpm idle
Any thoughts ?

 

I know this doesn't explain the "ran great then all of a sudden..."

Code 43 is usually a KS circuit issue. Key on engine off, did you check for voltage at the KS connector to ground? You should be seeing 5v signal volts.

Resistance measured center of KS to ground should be ~3.9k ohms.

Mines displayed similar symptoms with some wires crossed (not by me PO)...

Better yet follow the troubleshooting tree in the FSM (I know this is thirdgen.org)...if you get to the end the knock filter resides on the memcal. Idk when you changed the ECM if you reused the same memcal is what I'm alluding to.

 

Thanks
Been through the 43 flow chart so many times know it off by heart.
Everything is as should be ( test wise ) but problem persists.
On 90-92 '730 MAF ECM , IIRC , the ESC is not on the memcal anymore ?
Has custom tune on a 27SF512 chip using ZIP Moates adapter .
Replacing with a previously know good tune on a different chip had no effect

 

Previous years MAF TPI used a Electronic Spark Control Module in conjunction with a 100k ohm KS. Circled in red...this is the knock filter that is still being used even if you're using a Moates G1 adapter. I've never had a knock filter go bad before but were you able to swap that out since you said everything in the logic tree checked out? I don't think the bin has anything to do with the code 43 as I've mentioned it's a circuitry issue.

As you described, mine didn't do what yours is doing...not the best chart but it shows spark retard above a certain rpm at all kpas and increased with rpm.

...and this is after the botched wiring was fixed.