Not sure if I want to go SD or not yet.. Probably will but not just yet. Im only running 5psi at the moment.

First I see that my map sensor is maxing out. I have been told that I dont need to get a 2 bar sensor unless im doing a speed density tune.
Is there any reason why I can install the 2bar map sensor so that I can see my ltfts and stfts so I can see if they are sticking at 0's....
Also so that I can log my a/f ratio in that range with my wideband..
I assume I will need 2bar support with hptuners to log that 105kpa+ area as well.


Now tuning the ve table in sd mode planning to hook the maf back up..
It is correct that I only need to log 50+ hits for all cells under 4k rpms correct?
What If I do SD mode, do I need to hit all cells? Is that safe?
Also with a turbo how high in the freq do I need to lot to with a turbo? Past 10k? How many counts per cell do I need to hit..


Another problem I am having is when I log with wideband and use the a/f error.. I get everything looking good and the next day I do some more to make sure it looks good and the ltfts's and stfts's look good but the a/f error is off? WHY? Location or inaccuracy of wideband?


I have done the ve table and calibrated the maf... However when I plug in the maf it seems to want to put everything positive..
Maybe the MAF is going bad?
I have calibrated it many other times for n/a without a problem..
Actually tuned my car and others without problems before but the turbo is causing me problems..
I havent seen many writeups for turbo tuning.


I upped my ve tables around the 3200rpm and 60g/cy to 105+ and changed my pe around the 1.5xx range across and its still wanting to go lean under wot..



PS.. Im at work right now.. Ill post me tune and some logs if anyone can help out. Thanks and feel free to point me torward any turbo tuning guides...
I just found some stuff redhardsupra has done but havent had time to look at them yet..

 

this should answer most of these questinons:

http://tuning.wikispaces.com/tuning+Forced+Induction

 

Thanks.. Ill read through this stuff and get back with anything I dont get.

 

when that thing hits boost, its maxing out the VE. your WOT and above 4krpm is your MAF. I'm in the process of making an excel sheet about some things, that right now NO one is going to see so that they don't steal the stuff from me. When i get done with it I will share. Lets just say I'm actually doing the MATH on some things.

at only 5psi you will reach roughly 135.7893 kPa; which is 483.87 g/s of air on the MAF.(Could be more...could be less) but it is close to the 511.99 g/s capability of the MAF. You will max out your VE table and MAP sensor, BUT you will still have your MAF table and PE table adding fuel to your car. Try raising your MAF numbers more( if not maxed out), and if your upper limits are already at 512 and you are reaching that, increase your PE table even higher and get back with me on your lean condition.

I honestly see no need for SD at 5psi

 

whos page is this?

QUOTE:
MAF simply maxes out at 56lb/min, so the airflow number becomes a constant. END QUOTE


(512 g/s) / (453.6 g/lb) = 1.128747795 lb/s of air. which

1.1287 lb/s * 60 sec/1min = 67.722 lb/min

or did I do a calculation wrong?

 

512g/sec==67lb/min you're right
453g/sec==60lb/min
426g/sec==56lb/min which is about max what i've seen on a MAF
I haven't seen MAF being useful past ~56-59lb/min (i've seen it go flat on different cars in this range)

 

Mine doesn't seem to like to go past 56lb/min ether, even though that right about where its at with 170 kPa and 6200 on my 4.8

 

My maf is somewhere in the 50's right now.. Ill have to check it when I get home. Still reading some stuff.

Appreciate the info on the ve maxing out. Didnt know that.. Ill work more with the maf and pe table to see if I cant bring it down to the 11's afr..

 

well then that means at the 439 g/s stock limit that that is really what it maxes out at... at least i guess. because 56lb/min is 12.444 cubic ft/s of air ; which is then 431.827 g/s of air... close to the 439 g/s limit in the stock tune file.

and 59lb/min is 0.98333 lb/s .... and 13.111 cubic ft/s and 454.96 g/s...

well.....i guess i will see how this turns out on mine, and if i can get it not to flatline at my 5psi (62.8 lb/min.....1.04667lb/s ...you get the picture... 484.26g/s) I'll post what i did. but I'm going to bet that it will in some way flatline and not work as others have seen

 

I like to see at least a 10% headspace before the maf saturates or go SD. Many times I have seen guys tune to near the limit of maf, then go out on a colder, dryer night and blow their engine and wonder why.

 

? I have seen it stretch out on the few FI tunes I have done and more that I've looked at...

This was a month and something ago, when I had a single pump (and meth) that was running out a bit up top (cheated PE for FP drop before the second pump went in). It was preliminary WOT tuning @ about 11psi. In g/sec it showed 511.99; I changed the labeling over to lb/min since that's what the discussion was here:




Which leads to my next question.... If I log raw frequency why does it continue to climb AFTER that point? I am at 15.5 psi and about 17deg timing now on the street and the MAF curve goes straight up to max in the early 4K RPM area and yet the raw frequency logged seems valid.... If I plot it against the curve on a spreadsheet it seems that the MAF is still reading but we are at the limit of the PCM's input. Thoughts?

 

and even being if we are at the PCM's input, does it/why shouldn't the pcm still average the data being collected at the sampling rate it can read and still collect data and not max out?

 

thinking since I posted.... it can't be an input sampling limit (doh!) since I log freq thru the PCM, must be a limit of a table or internal calc... The designers just probably figured that it extendeds so far past normal and since it fully covered every conceivable factory range that there was no need to work with higher values.

 

Yes the max table value is 512, likely a 9bit integer. There is no way to tell the pcm you are getting more than 512g/sec unless you run SD.

 

It's not about telling it, it's about what it does with it once it's told... you can log raw freq. and see that it continues to climb past this limit.

 

Sorry to bring this one back up from the dead but this is some interesting conversation. I think ringram is right about the factory assembly only reading 9 bits (max of 512) but the register is likely an 8 bit register which means they would be reading from two registers. If that is truly the case, a code change would allow the table(s) to extend up to 65536.

I think Frost has a point in that the original assembly was written to facilitate the needs of a factory engine so they didn't code beyond that original 9 bit integer. Or perhaps anything higher is out of the spec range for the maf's design parameters so they don't rely on it above that point?. I'd be curious to see a datasheet on the maf.

Anyone have the original GM source? lol

 

LOL. that would be nice