hrcslam

I've only been tuning for a little while, but I know what you mean. I was told don't worry about the VE tables in MAF mode, and my dyno tuner adjusted my VE tables and PE tables in MAF mode for WOT. The best tune I have so far is the one I did after my dyno tuner (for drivability anyway) where I did my VE tables without PE engaged in SD mode. Then when those were perfect I enabled PE mode and calibrated those tables based on a calculator I built.

I've recently taken a look at my spark timing (the dyno tuner had it at 26° at WOT) and reloaded the stock spark timing tables plus 2° over 4500rpms. I'm getting knock over 4500rpms under load, so I'm pulling 1° until I get no knock. Right now I'm at 34° and still need to do another datalog (I'm not rushing the process).

Anyway, that is all to say, I agree. There is no "wrong way" to tune between all tuners not all will agree. I've been given crap for tuning my VE tables at all in MAF mode, yet my MAF tables are now stock (again) and my VE tables changed drastically. It worked for me, but I'm not sure why. These LT1 PCM's are weird (like the mysterious timing). If my car was a weekend warrior I'd likely have left it how my dyno tuner did it, but it's my daily driver so drivability and reliability is a big concern for me. So I need every aspect of my tune spot on.

If the VE tables are correct, the stock MAF calibrations should work. I think the only time a MAF calibration should be adjusted is if the location of the MAF is changed in reference to stock.

I used the link I referenced in his response to read plugs. It will tell you a lot, WOT and Cruise AFRs and Spark timing. Pretty cool stuff. I agree though, you can only read so far into the past of the engine to see what's going on. If tuning based on plug readings you'd have to clean (or replace) them after every data log and tune. That would suck.

moehorsepower

iTrader: (3)

LT's like timing at wot from 33* all the way up to 39*, yes 39. Of course this was a very ragged edge tune for a pro outing, but this is what the motor wanted with no KR, of course as you know the more efficient the combustion chamber the less timing, this is why LS are only at around 28* because of the superior chamber vs the LT, always remember every engine being the same combo is different, I never load a tune from another that has the exact same setup, I tune each one separately. Give it what the motor wants, but of course keep KR at bay, read your plugs not only for A/F but timing and heat range also..

hrcslam

Yeah, my tables showed 34° advance at WOT, but you know that mysterious timing the ECM adds? I'm data logging 40-41° spark advance WOT. I've since pulled 1° and will data log it next time I drive. I'd imagine I'll end up right in the range you stated though with actual spark advance, not commanded.

hrcslam

JC1994, I got your MAF-less data log. Those VE tables look even better now, they could use a little adjusting (need to add a little more to a few cells) but I can see why you said it runs better.

Looks like it may be time to get that MAF calibrated. But, before you do that makes sure the MAF is clean and the connections are good. If the MAF is in the stock location, it shouldn't (this doesn't mean it doesn't) need calibration, but you do have the tiny Ebay CAI right?

hrcslam

Also, posting the data logs here would be beneficial to everyone else that have the same questions you do. And others with more experience or different opinions than mine can view them and advise you too.

I've attached them for others to review. I will not share your tune though, that is yours and your tuners.

Jc1994

Thanks, but the CAI is like a 3" steel tube. Already cleaned the MAF sensor with alcohol.
My buddy at work has a 94 Camaro should I try his MAF?

Jc1994

Or should I put the OEM air box back in? Think the CAI is causing a lean swing? Maybe, but usually I haven't had a problem with other vehicles.

Jc1994

Ohm test MSD coil-secondary 5.86 Kohm primary .5 ohm. Spark tester got up to 30K before it stopped jumping-thought these where higher than that. Have another AM coil that tested 11 Kohms secondary, but have not tried it on the card. Suspect MSD to have lower resistance because it is higher current? But don't you need higher K-volts?

Jc1994

Also did I mention that I have an AM high volume fuel pump and line off the req pressure is 47 psi. Have not road-tested with gauge on to confirm WOT pressure, but I will do that.

hrcslam

Seems like fuel pressure is good.

I'd think you should get spark at 30K, I thought the MSD coils delivered 30-45K. Why no spark over 30K? 0.5 and 5.5K ohms is right where it should be.

What is your coil actually pushing? Maybe make sure your Coil has a good ground, clean the contacts and use lithium grease?

The CAI is possibly changing the calibration the actual airflow to hertz ratio in the MAF, speculation at this point. You could always throw the stock intake back on and monitor the BLMs on a data log and see if they improve (MAF connected again). I'd be interested to see those results and the results of the IAT vs Ambient too. I don't have my stock unit otherwise I would've done it already.

I don't think swapping MAF's will do anything as yours seems to be working properly.