Open Loop Maf Tuning

[mtcrusan]

Question: Without Open Loop tables in a V6 is there another way to command a lower afr during cruising speeds? Of course once I complete a decent tune first.

[Russ K]

The open loop tables don't affect the closed loop commanded AFR. The stock O2 sensor will keep the AFR close to 14.7 in closed loop. The Gen III V8's & the V6 trucks have a rich/lean O2 sensor MV table, by lowering this table, the you can lean out the closed loop AFR.

Russ Kemp

[mtcrusan]

I ran a few WOT in 2nd gear and logged and modified my WOT afr. It got pretty close in most cells, but one 7500 Hz or the next one higher was 15% lean. I MAF table looked rough. Is it ok if I smooth that out a bit and re run again?

[Russ K]

Yes, I always look at the maf table in 2d view & manually smooth the graph.

Russ Kemp

[mtcrusan]

Thanks Russ!

[BEEDEEBEE]

I just got my HPtunersuite in the mail a couple of weeks ago and haven't hooked it up yet (car is still parked for the winter). I also bought a wideband which is sitting here. I was planning on getting the wideband installed first but after reading this I'm thinking not.

Is the open loop MAF tuning the very first thing I should do?

[mtcrusan]

Could you post your stock tune? Looks like your knock sensors need to be desensitized.

Russ Kemp

Has anyone looked at this? I continuously get 4 - 6 degrees of knock on my 2nd gear runs. Will race gas hurt my pistons if I use it to try to use it to find out if the knock is real? 5 gallons? TIA!

[Russ K]

Mitchell,

Try this tune, I desensitized the knock sensors, adjusted the Maf table as per your scan, and set up your shift pressure & TCC duty cycle tables. I would install a one heat range colder than stock spark plugs.

Does your car have a performance shift button?

Russ Kemp

[mtcrusan]

Russ,
Thanks! I am running Autolite 104's now @ 0.050 gap. 2 heat ranges colder than stock. My monte does not have a performance shift button.

Is my MAF coming together?

[JFDugal]

Try not to change too much stuff at once when you're attempting to tune out a problem. How will you know which change worked?

I'd start with the MAF changes and the knock recovery rate. Also lower the KR Min ECT to 100F.

And you should be fine running a bit of unleaded race gas to test for false knock.

[LNorton]

Try gapping those at .040 instead. Should cool the spark and help with your knock issue.

[mtcrusan]

Russ, I flashed the file you sent me, but just cruising it would shift hard just cruising about 45 mph. I flashed back the previous file I had and I noticed the MAF freq. really high. Do you know what this could be?

[PDXGTP]

Try gapping those at .040 instead. Should cool the spark and help with your knock issue.

I agree, I was going to suggest using the Autolite 103's gapped at 0.042". This works really well for me.

[LNorton]

I had an issue when I first put a cam in our car where I could not get the knock to go away, even down to 18* total timing instead of up around 25*. Went from an Autolite 606 gapped at .048 to an Autolite 605 with .038 gap and it helped a ton. With that plug I can run around 27-28 degrees of timing, and should be able to bump to 30 with the AFRs around 13.7 at WOT.

The first thing you need to do when evaluating a problem is look at fuel and spark first. These need to be in line before you worry about the PCM. The wrong plug or a bad plug, bad wire, lots of things, and a perfect tune up can run just as bad as perfect working parts and a really bad tune.

[Amped]

I don't have a WB yet, but I went through the process in this thread to learn the VCM suite. Then I realized that the resultant data wouldn't help me because without the WB AFR readings then no AFR % error can be found.

However, I ran a scan anyway with the front 02 sensor disconnected and modified tables per the OP. Why did my commanded AFR settle at 17 instead of 14.7?

[Amped]

Nevermind. I forgot to zero out the PE Add VS TPS table. 14.7+2.3=17.0

[mtcrusan]

Mitchell,

Try this tune, I desensitized the knock sensors, adjusted the Maf table as per your scan, and set up your shift pressure & TCC duty cycle tables. I would install a one heat range colder than stock spark plugs.


Russ Kemp

Russ,
I used the config you changed. I did another WOT run in 2nd gear. Still showing some knock. I corrected the MAF again and should be able to run again this afternon. Thanks!

[mtcrusan]

How close should the WOT MAF table be? I have one area in the transient stage that spikes lean. Then I correct it and the next run it spikes fat. TIA!

[mtcrusan]

Also I am going to get some 100 octane gas to see if the KR is real or not.

[MMGT1]

How close should the WOT MAF table be? I have one area in the transient stage that spikes lean. Then I correct it and the next run it spikes fat. TIA!

Are you using the "multiply by % half" function whan adjusting your MAF table?