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it was not the lean condition that melted the spark plugs
in your car in your system
lean condition DID NOT CAUSE high combustion temperature .
your tampering with MAP voltage DID
by reducing the LOAD signal, the ECM provided ignition timing based on a lesser than REAL / ACTUAL LOAD so ignition timing was ADVANCED , TOO ADVANCED for actual conditions
if the ECM had been provided with a feedback signal from the AFR or front 02 sensor , the ECM would have attempted to compensate for the lean condition caused by reduced load signal .
BUT
the ECM would NOT have attempted correction to IGNITION TIMING advance .
peak combustion pressure was happening TOO soon , the engine was "pinging" and you either did not hear it or chose to ignore it .
...."I removed the factory o2 sensor to put the car into open loop and to use my wideband, but I was tuning beyond it's capabilities. Timing was stock.
>>>> Map voltage was reduced by 30% <<<<
last wideband reading was 19:1 before reducing a bit more fuel and maxing out the o2 sensor. Average RPMs were 2200-2600. Average MAP pressure was -19.7inHG and maximum was -11inHG.
Took it for a test run and car started smoking, and stumbling. Wouldn't hold idle. I got it home, checked the plugs and found my problem. This being my daily, I decided to forgo any extreme tuning as such until I can find a wideband that is capable of accurate readings at > 18:1"....
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