Maxed out MAF Table LQ4 need suggestion on MAF upgrade

[hhoelle]

Okay maxed out the MAF table running 12000 Plus with a 2300 supercharger on a 6 liter. It's a 2001 DBW 2500 GMC factory 78mm throttle body and factory ECU with HPTuners 2 bar enhanced OS, does anyone have a suggestion on how to upgrade the MAF or overcome the situation. Any help would be appreciated. Injector duty cycle jumps from 71% to 103% when MAF goes beyond 12000.

[Ranger6202]

go ls2+ slot style and increase the pipe diameter where the slot maf will be

[hhoelle]

Thanks for the reply, I am using a 4"Aluminum tube assembly with the stock MAF so if i add the LS2 MAF how will it keep the MAF readings from exceeding the 12000 range in the table? When it reaches 57 lbs/min it exceeds the 12000 max side of the table as can be seen at 13.14.641 of the log.

[mowton]

So here is my theory, you havent tuned your VE and it is sitting at a straight 129 and when you hit 12000 you get a MAF Hi fail and it reverts to SD. Try setting the MAF HZ Hi value to 13500 and see if it stops the overrun. Your injectors are fine as you said until the MAF fails and then it jumps to 20+ms at 6000.

Additional observations...You need to tune your MAF, see how it leans out as you hit 4000+rpm and build boost. You are running dangerously lean and that is supported by the precence of knock. If at some point you exceed the 512 g/sec ceiling, then you will either have to scale the tune or run Speed Density. Also you have entered 2 bar parameters in tune, log the 2 BAR MAP from the AUX Input List>MAP in the PID List. Delete the single bar PID. And try not to log anymore than 24 PIDs at any time to maintain proper resolution and sampling rates fro the data. Lastly tune the VE at least to be in the ball park.

Ed M

[Ranger6202]

good call motown! i was on my phone and couldn't view his tune or scan.

[hhoelle]

mowton and ranger6202, Thanks for the replies I really appreciate it. I did tune the MAF in a later log this was an earlier log showing the spike I didn't have one later than this one with WOT as I was tuning the MAF to get rid of the lean mixture and have it tuned right now. Didn't want to push it to that point again until I had some answers As to how to handle the overrun. now that I have the MAF tuned I'm going to work on the ve tables. Thanks for the input on logging the 24 pids I was not aware of that. Will move the MAF failure to 13500 and work on the VE tables. Thanks again really appreciate the help.

[hhoelle]

Thanks for all the help. Changing the MAF failure to 13,500 fixed the issue the only problem was that I now exceeded the 512 g/sec so I Decided on the SD tune as. Removed the extra pids which helped the data and while I changed to SD tune decided to fit a 90mm throttle body which was fun to make work as it is DBW. I did pick up more boost now trying to work out the hot start issues. Thanks again for all the help.

[mowton]

Thanks for all the help. Changing the MAF failure to 13,500 fixed the issue the only problem was that I now exceeded the 512 g/sec so I Decided on the SD tune as. Removed the extra pids which helped the data and while I changed to SD tune decided to fit a 90mm throttle body which was fun to make work as it is DBW. I did pick up more boost now trying to work out the hot start issues. Thanks again for all the help.

Just for your notes, instead of developing an SD tune, you could have scaled the tune by say 20% to pick up an additional 100 g/sec head room, but good you got it sorted out. Love it when a plan comes together..

Ed M

[hhoelle]

Just for your notes, instead of developing an SD tune, you could have scaled the tune by say 20% to pick up an additional 100 g/sec head room, but good you got it sorted out. Love it when a plan comes together..

Ed M

Thanks mowton it did so far. I thought about scaling the tune but was not able to find enough information on exactly which tables to scale so opted for the sd. If you have a link to a post with the information to scale a tune it would be great as I am trying to learn as much as I can about the different options. Thanks again.