SD v/s MAF tuning?

[dragracn]

Been lurking the site for a while now. I have read alot of the post about running a MAF with forced induction but am still not sure which way to go. I have been tuning for a while, not great at it but have had some pretty good results with a few I have done.

Truck is a 97 Chevy DW 1 ton 454, with upgraded 411 computer in MAF mode still. I installed a turbo and run it at low boost (6-10lbs), it is an every day driver/tow vehicle, we use it to tow a fairly heavy fifth wheel camper. Its does NOT max out the MAF. I am controlling fuel just thru PE. It runs good but I am having a little issue with spark knock and having a hard time controlling spark advance. Its more then what is commanded while under boost.

If the MAF is not being maxed out is it going to be worth it for me to go SD and get more control of timing and fuel? This is a DAILY driver that we use in different conditions and travel with and I don't want to have to re-tune every few weeks for weather/elevation.

Thanks for any info.

[Pekka_Perkeles]

If the MAF is not being maxed out is it going to be worth it for me to go SD and get more control of timing and fuel?

I would say no. MAF will be the base for your fuel calculations, just as GM intended it to be (over 4000 rpm's).

Tune your igntion advance to get rid of knock. AND before that, tune your MAF to get fueling right.

Just my opinion.

[dragracn]

Been lurking the site for a while now. I have read alot of the post about running a MAF with forced induction but am still not sure which way to go. I have been tuning for a while, not great at it but have had some pretty good results with a few I have done.

Truck is a 97 Chevy DW 1 ton 454, with upgraded 411 computer in MAF mode still. I installed a turbo and run it at low boost (6-10lbs), it is an every day driver/tow vehicle, we use it to tow a fairly heavy fifth wheel camper. Its does NOT max out the MAF. I am controlling fuel just thru PE. It runs good but I am having a little issue with spark knock and having a hard time controlling spark advance. Its more then what is commanded while under boost.

If the MAF is not being maxed out is it going to be worth it for me to go SD and get more control of timing and fuel? This is a DAILY driver that we use in different conditions and travel with and I don't want to have to re-tune every few weeks for weather/elevation.

Thanks for any info.

I have calibrated the MAF. The spark issue is one of the reasons I was wondering about going to SD, timing will not go below 10* no matter whats commanded. I can go over 10* and it will go to what ever is commanded in the timing table. I had a bad knock sensor that would go to full KR once in a while and it would pull the timing below 10* then, but it was still just the max KR under 10* (max KR 8* from 10* = 2). I wasn't sure if the computer went to a default after the calculated cylinder airmass goes beyond the timing table? That seems to be when the timing goes to 10* and stays there (unless I have the botom of the timing table set higher then 10*), is once the cylinder airmass goes beyond the timing table. Its my understanding if I put a 2bar MAP sensor on its not going read it still untill I go to SD? Is there something I'm missing in the spark tables?

[Pekka_Perkeles]

Post your tune.

Also, what is the Min Spark Advace vs. RPM setting(s) under Engine/Spark/Retard?

[dragracn]

Min spark is -15. I messed with it yesterday some and went over some old logs, it seems as thou when it starts to build boost the cyl airmass jumps up very quikly (faster then the computer reads??) and goes beyond the timing table, it looks like it does this quick enough that it keeps the timing fromthe last cell in the timing table it was in before it goes beyond it. It just happens to usually be about 10*. But 10*is up in the .98-1.00 area of the timing table, the table goes to 1.20, but it never shows that, it just goes rite from .98-1.0 to a higher value out of range of the timing table? Not sure if i explained it well enough to understand?

Im on my phone and will try to figure out how to post tune tomorrow.