vbMike

iTrader: (2)

I’m new to tuning and I’m trying to get my air fuel mix dialed in a bit closer. I upgraded the whole exhaust system so now with the factory tune I’m running lean, no surprise. The BLMs are anywhere between 128 – 140, sometimes even higher.

I have the 165 ecm and running $32B code. I’m using tuner pro to modify the fuel table. I forget what it’s called but it’s has rpm, load, & the injector value. I know that I need to increase this number to add more fuel at the corresponding rpm & load that are running lean. The problem is I don’t know how much to increase these values. I make a change but it doesn’t seem to bring down the BLMs at all. Is there a formula that can be used like if you BLMs are 136 take the current value and add this much more to get the BLMs closer to 128?

Also what about idle, it is running very lean at idle and I made what I thought would be a significant change in the table for the 400 – 800 RPM range and 32 – 48 load range but it didn’t seem to make any difference. Is there a different table to control the idle?

90c350

I am pretty sure that if you take the current BLM# and divide it by 128 that will give you the amount to adjust you main Ve table by in that cell. example current blm# 140/128=1.09 Multiply your current VE cell # By 1.09. Example AT 50kpa at 2000rpm Ve cell # is 45.20 So you would multiply 45.20 by 1.09 to give you 49.27. THat would be roughly what your new Ve setting would be in that particlular table. This should bring things in a little closer and then rough in the rest of the table as well. THis will take a few tries to get it right. HOpe this helps some??

87 Vette Owner

His set up is MAF, not SD; there are no VE / map tables in $32b.

You can tune using the base pulse width tables, but to do so you need to uncheck the "Base PW Calibration Method" element in the "Flags / Switches" list. You aren't seeing the effects of your changes because of this. It is referenced in this thread:

https://www.thirdgen.org/forums/diy-...b-tunning.html

I prefer to adjust fueling using the MAF tables. It is probably the easier and more popular method.

vbMike

iTrader: (2)

Thanks 87. I must have missed that part about changing that setting when I read that article the first time. So currently this table does nothing with that setting turned on? What does the car currently use to calculate it's pulse width if it's not using this table? Apparently it is look at the MAF table to see how much air the engine is using and then adds fuel based on the MAF value. But where is the table that tells it how much fuel to add if it's not using the BPW table?

Even though I'm not using speed density wouldn't the technique that 90c350 still work to get me closer to 128?

87 Vette Owner

In your data log, you can compare MAF gms/sec to BLMs to see where they are settling in at the average gms/sec readings. I like to sort by MAF gms/sec and review the BLMs accordingly.

90c350

Ok sorry guys for not paying attention to the original question and the application. Oh well I tried. Glad to see you guys spoke up and help out as usual. Good luck!!

87 Vette Owner

No worries 90c350! I had to change the wording in my last sentence because gms/sec is what generally shows up in data logs, not voltage. (I happen to be data logging MAF voltage, hence the screw up ).

vbMike

iTrader: (2)

Thanks guys. That made all the difference in the world. So with this switch changed are the MAF tables not used now? If yes, then is the MAF sensor even needed anymore?

Another question, how does the engine know how much load it is under? Is it calculated based on the amount of air consumption reported by the MAF?

87 Vette Owner

The MAF sensor itself is still used to measure airflow, but I believe the fueling is determined by the BPW tables instead of the MAF tables. Either way, you still need the MAF sensor .

Post #4 in this thread starts to explain how load is calculated:

https://www.thirdgen.org/forums/diy-...scellanea.html

That is a great MAF thread BTW!

dimented24x7

iTrader: (2)

NVM.