Triumphrat

rickster · 05-12-2008

I recently bought an Innovate LM-1 Wideband o2 sensor/datalogger to examine/develop my mapping, and finally had some time to play around with it. I'm logging rpm, TPS, and the Lambda/AFR. I noticed that at idle the AFR reading hovers around the high 17's -high 16's immediately after restarting the engine when hot, and it takes 20-30 seconds for it to return to the 14.5-14.8 range. It does the same thing immediately after slowing to a stop. I've run it using the LM-1 analalog output to emulate the stock o2 sensor, and I also installed an extra bung for the wideband sensor to use it strictly for monitoring- same results. Am I crazy or is the ECU very slow to respond? Could this be related to the stumble/hesitation during rapid throttle opening (i.e. downshifting) that I haven't been able to tune out? Should I petition my dealer for a new ECU???? I reset the TPS before doing any testing, did the charging system mod. some time ago(14.5v all the time while running), and have had no error codes. I'm currently running the Massive Midrange tune, and neither of the above conditions have changed at all between tunes. ?????????

DEcosse · 05-12-2008

First question - do you have SAI?
(I guess not if you have MM)

TechmanBD · 05-12-2008

That is normal for A/F gauges in idle. My Mustang does the same thing and I thought something was wrong with my gauge. I found out that is normal. You main concern is more of wide opne throttle.

bradtx · 05-12-2008

rickster, My '89 Mustang's AFR meter shows the same as TechMan's. This seems to be an emission's thing as even during the later carburator days in cars a decel valve was incorporated to lean the mixture.

Brad