pcmhacking.net

thought id post an example for you all to analyze lol, tuned this car with enhanced mod v1.2 not yet released. Attached is dyno log and a WOT run in tunerpro. Not sure what's going on with AFR's the innovate MTX-L reads 11.70 but NGK tailpipe meter on dyno reads leaner

Car details:
VT L67 3.5" Pulley "10psi", 5% OD, exhaust & extractors, rebuilt auto with 2200rpm stall, everything else stock.

Great numbers and on a mainline dyno too.

Tailpipe will always read eager in a car with cats, won't it?

That dip in the top looks like classic valve springs going off.

yeh that's what i put it down to being cats messing with the readings, but you'd think an expensive tailpipe meter would be close.

It's running stock 5900rpm limiter.

Yeah I've heard tailpipe normally reads leaner too and I've seen the same on the Dyno myself, but not that much difference!

thats my car lol

Needless to say... its been going much harder since The1 has been tuning it... and its been fun and Ive learned a lot too in the process. My mate borrrowed the car recently and he couldnt believe it still had the same engine in it.

Hasn't even got rockers on it yet... I'm sure we would have seen at least 235 - 240rwhp with 1.9x rockers

Nice result

Wideband before and after cats will read differently, leaner post cats. How much different is generally how well the cats are working I think. If you log pre and post cats during closed loop you won't see the rich lean swings post cats if they are working OK. This is how the pcm can determine catalyst faults on obd2 cats.

cool.... so does that mean my cats are working well?

Schwuppes wrote:cool.... so does that mean my cats are working well?

yep and thanks for sharing and tuning with me, has been good, now your off to get a map a2a kal lol anyway

normally there isnt as big a difference as what you've seen but it relies on no exhaust leaks but the time you get to the rear and also having an extension tube that goes right up the tailpipe to prevent any outside air contaminating the reading.

The1 wrote:

Schwuppes wrote:cool.... so does that mean my cats are working well?

yep and thanks for sharing and tuning with me, has been good, now your off to get a map a2a kal lol anyway

yer ive crossed over to the dark side for now lol... main reason is it just makes it easier: drive in, drive out... all tuned and ready to go... dont have to worry about anything.

but yer I'd be willing to give delco another go once I have some more spare cash to get that bigger LS7 MAF etc... then go back to back on the dyno: kalmaker vs delcohacks