lcvette

iTrader: (3)

as title states, has anyone explored the idea of using two MAF's in a turbo system, and finding a way to devise a circuit that sends the average signal to and from both MAF's to the ECM so as to keep the readings in the PCM within spec and then adjust the MAF tables to reflect proper fueling? just a thought, not sure if it is at all possible or not but if so, maybe some of the more experienced PCM guru's can explain why or why not. just trying to brainstorm on a few ideas here!

Chris

MYTURBOT/A

I think Harlan's running a setup like that, but he'll have to chime in with the details.

lcvette

iTrader: (3)

Awesome, i was expecting that to get shot all to hell..lol always cool when you have someone who has figured something out that is not so common a solution, I am looking forward to reading the posts about how he designed this to work!

Chris

rons 00z

iTrader: (10)

i mentioned this a while back and it just got shot down. i have no clue how to tune so dont even know how i'd make it work. i'll i could do is the easy labor and thats about it.

DERTY

You're pretty much on track. Harlan runs this on his. But you have to know how to take in the input frequencies, add them together and average them out. Unfortunately he's the only one that can probably explain how he did it.

69firebird

iTrader: (14)

i believe that the tricky parts is are you talking about using a twin or single setup turbo wise? On a twin turbo application this will work out pretty well but I am not so sure that it will work out the same way with a single
ed

XLR8NSS

iTrader: (4)

It could work on a single setup, you'd just need the MAFs in parallel which might present some pipe packaging problems.

Any electronics guru could probably figure it out, except Harlan already has.

69firebird

iTrader: (14)

ok,
I know that I am not an electronics guru, but I dont see how running two of them in paraell would relly help anything? if one cant read the air, going through the first one, then how would the second one in the row be able to read it any differently??

again this aint my forte so if this post is too simplistic and dumb i apologize
thanks
ed

DERTY

Same way you would use it for twin turbo. You are thinking series, e.g. one maf after another. In parallel the air passing through one would not pass through the other.

2FAST4U

Well Harlan is busy <--is my quess! As always!!

I think he has 2 mafs and a non stock PCM and rewired is a huge understatment! One maf does 1 turbo and 4cly. and the other does the other side!

I can be wrong but this isn't something your average joe will be doing one saturday as a mod!

lcvette

iTrader: (3)

lol, yeah, not a saturday mod for sure, but then again fabbing a completely custom turbo system for a C4 corvette which there are no kits for is also not a weekend endeavor... Just trying to think of some odd ball ways of making things work.. I have an hour commute every day to and from work, thats alot of time to get comfortable on the long boring drive and think of any and all possibilities.

I have even gone so far as to consider piggy backing the engine sensors to a second PCM and running a second set of injectors with it, this would cure the issue of needing larger injectors..lol just need more of them. could also use a second MAF this way with very little issue, and you would essentially be able to double the air flow amount and keep proper fueling. I imagine you would just kill off anything not needed for the second PCM to function, and this would give you air flow accuracy pretty much as high as you would want to go unless your attempting to build a 1200 plus HP car in which case the way to go would be the FAST or Gen VII.

also, if there would be some way to to keep the second set of injectors from firing unti the car was in boost like a hobs/pressure switch, the cruise and idle would be EXACTLY the same as stock. then when you hit boost, the secondary fuel pump and injectors come online. very similar to using a secondary fueling system similar to whats on the Callaway vettes just using more injectors with alot more room for growth. figure if need you could pop in 2 sets of 42lbers and have the great tuning characteristics they have plus the extra range with the MAF. also the second PCM could be tuned more so to work with boost while the primary was tuned to work more geared towards normal driving. I dunno, I just get off on tangents sometimes. maybe someone else has thought of somthing wacky like this, I am just the glutten for punishment who posted it..lo fire away!

Chris<----- Ducking

Got Me SOM

iTrader: (2)

i guess you could try throwing both maf's on and see if it works. sounds like it should work.

good luck

sounds like you need a DFI or MoTeC for secondary injectors to come in under pressure. I know its been done on the import circuit, (the all out race turbo imports)

DERTY

Putting two MAF's on won't work without adding them together and then averaging them back out. There are some other gotchas that you have to figure out with dual MAF's at idle on a boosted application as well.

Harlan is out of town on business till Friday. I'll grab his attention and point him in here. We've talked about all sorts of wacky stuff like dual injectors too. A lot of stuff is possible if you have enough patience with working on the factory stuff.

lcvette

iTrader: (3)

great, I am just trying new things out, i have never been one to follow the trend when i can build something myself, much more rewarding even though it is generally a hair pulling experience. i think but am not 100% certain that the injectors are ground activated, if this is the case, it might require using 8 different micro switches driven off a hobs switch, so when out of boost the 8 switches disconnect the ground circuits for each injector lead, and once the hobs switch is activated under boost, it would close all 8 circuits and allow the ECM to fire as it normally would. just have to do some research on whether or not the fact that the ECM is sending a signal and not getting one in return will freak it out. that ECM would not be connected to any fault lights or SES lights so as long as when the grounding circuits were closed and the internal ECM switches began controlling the injectors without incident it should work. this is a very general overview and it is subject to be completely wrong without field testing first, but just a starting point. I may take on this project if i can get enough information from some of the previous pioneers of radical ECM function changes. would certainly be neat if it could be made to work. in essence, ther factory shell for the ECM could be enlarged to accomodate the other internals and simply useadditional harness connectors for the additional wiring harness needed. as cheap as i have seen PCM's and factory MAF's and the price of smaller injectors, you could basically have all you needed with accuracy to boot! looking forward to harlans input on this since he has some experience and can rightly say yay/nay to the feesibility of it, but very much enjoying the topic!

Chris

M_T_0

I THINK that you can get this done with out the second MAF. If you just install a bypass around the MAF, ie a bypass tube that will allow 40% of the air to bypass the MAF then scale the input in the PCM, the MAF would still be reading the airflow less 40% and it should be just a matter of scaling. this would eliminate the need to average the 2 MAF's or do any electronics


And No i havent tried this so this is all just IMO.

M_T_0

rons 00z

iTrader: (10)

there is no for sure of how much air is going through the bypass because it's not being measured so your going to have inaccurate readings. hell if you ask me hook them up in series find out how much of an ohm increse you get then use what ever ohm resistor(s) to normal it out. now from what i understand the maf is a heated resistor so if there is any frequency involved it's just a carrier and most likely wont be affected. i dont think there is a frequency though because it's a dc circuit but i could be wrong.

MIGHTYMOUSE

iTrader: (59)

guys should try the search this topic comes up in a big way about every 6 months.

i run 0 maf's and it works good too

lcvette

iTrader: (3)

i tried a search on several similar topics, and got nothing... any suggestions on what to use as search criteria?


on the bypass tube, this would be difficult because unlike measuring metered air at a set vacuum/pressure the characteristics of the bypass tube would vary greatly. and knowing at what exact point to get the 40% airflow difference and have the MAF read accurately still would be a trial and error method that would take a very long time to pin down..this is all speculation though.. perhaps 40%@28 inches of water as measured on a flow bench could be correct, just don't know!

possibly enlarging the actual size of the MAF housing allowing a high volume of air through and simply rescaling the other tables to interperet the input from the MAF would work.. much like using a resistor, except that by enlarging the housing, you would essentially be slowing the airflow rate across the MAF wires with the same volume still being ingested by the engine. this would require numerous dyno runs to get the AFR correct with the other tables in the PCM and make sure that everything was playing well together..lol oh well, any word from Harlan yet? dying to find out what he did and any advise he might be willing to share on it! keep posting guys.. this is great stuff!

Chris

MNC5

DUH, Leave it to MM to add to the content Perhaps something has happend in the last 6 months

69firebird

iTrader: (14)

MM,
do you run your DFI in closed loop?
ed