Split Second AFM To MAS Conversion (Split-Second / SplitSecond)

junglejustice · #1 (**permalink**) 01-02-2008, 10:10 AM

I did a search and incorrectly started some posts related to Split Second in another thread (not dedicated to the subject of Split Second and their signal conversion and MAF/MAS-conversion products.)

In order not to hijack that thread (actually related to another engine management alternative), I'll post my findings here after meeting with Split Second today (as well as hopefully further details on the conversion - once I go through with it!)

The goal is to get rid of the small and restrictive OEM flapper/crapper AFM and install a hot-wire MAS-type pass through air meter AND to have it function stand-alone and fully independent (pushing the correct signals/voltage/resistance) for a no-fault operation and no CEL light activation on the stock Bosch Motronic ECU in my 3.45 litre 24 valve 164.

iachella · #2 (**permalink**) 01-02-2008, 04:42 PM

Yes, do post. I have been reading their site and don't really understand the difference between their ARC2-A and PSC1-004. I was interested in the minimum needed to get rid of the AFM. I already have already purchased a Bosch MAF that is 3" diameter so I don't want to get their whole kit.

junglejustice · #3 (**permalink**) 01-03-2008, 01:04 AM

From talking with them today, it sounds like the -004 is the one that we would both need! The thing for me (and you) to go and do now is to verify the voltage output of the particular MAS meters that we purchased... Where did you get your unit from? What brand/make/model did you get.

Mine came from some guys in England off of fleaBay - some name like Pinnacle??? maybe...?

They will likely be 0-5 volts (just like the OEM AFMs), but just check. We would then use the PSC 1 units for calibration.

349 dollars each.

**Craig** · #4 (**permalink**) 01-03-2008, 01:22 AM

G'Day Guys,

Can it handle the 'burn off' pulse required by a hot wire sensor? Why not use a hot film sensor?

Let me know the part no. of your MAF sensor, if it's Bosch I might have the specs.

iachella · #5 (**permalink**) 01-03-2008, 09:57 AM

Mine comes from a SAAB and is part number 0 280 213 012. I got it used locally for $40. Here is a pic with a cell phone camera. It's grainy, but many Bosch MAFs look identical.

Did you get an explanation from them what exactly is the difference between the two? Is it something you can explain here? What about connectors, would it be plug in, or do we have to find some connectors and do some splicing/wire colors to-from, etc?

**75evo** · #6 (**permalink**) 01-03-2008, 10:50 AM

The burn off will not happen with anything but the motronic ECU. So you may risk the chance of deposits sticking on the wire. But if you can periodically clean the wire without destroying it, that should be fine too.

iachella · #7 (**permalink**) 01-03-2008, 11:03 AM

So a Motronic ECU system with a flapper AFM is capable of supplying the burnoff cycle if converted to a MAF? How would it know to do that? I understand we would be fooling the ECU. It won't know the AFM is replaced. I would think the signal conversion/conditioning section would have to supply that. Am I wrong?

**Craig** · #8 (**permalink**) 01-03-2008, 12:55 PM

Quote:

Originally Posted by iachella

So a Motronic ECU system with a flapper AFM is capable of supplying the burnoff cycle if converted to a MAF?

**Razzo rosso** · #9 (**permalink**) 01-03-2008, 01:19 PM

Hi all

There is a general consensus that hot film MAFs are more reliable than hot wire MAFs and don't require burn off. Not that I have any direct knowledge either way. They are just as inexpensive, or expensive if you buy them at the dealership. Watch out for the Asian junk, especially on ePay. Spec sheet is attached.

I'm told that the PSC1-004 is highly tunable and very reliable, although may be best sited outside the engine compartment to avoid heat and electrical interference. With the PSC1, you don't have to worry about which specific model of MAF you are using, however there is still the debatable issue of how best to measure air inflow temp. If someone has a working solution for that, I'd love to hear about it.

Regards
Simon

**Razzo rosso** · #10 (**permalink**) 01-03-2008, 01:21 PM

Try this site for connectors

RJM Injection Tech » EFI Harness Pigtails:

iachella · #11 (**permalink**) 01-03-2008, 01:23 PM

Thanks Craig. Mine appears to be #3 on the spec sheet. Of particular note is that it doesn't appear to have the idle potentiometer circuit like #1 and #2. I wonder how important that is. My AFM has an adjustment but I don't know much about it. My twin spark is the first EFI I've owned.

It also appears to be a 5V signal, which is consistant with the AFM signal. The signal conditioner should be usable with this MAF.

**Craig** · #12 (**permalink**) 01-03-2008, 02:46 PM

Quote:

Originally Posted by Razzo rosso

however there is still the debatable issue of how best to measure air inflow temp.

iachella · #13 (**permalink**) 01-03-2008, 03:59 PM

From the hot film MAF specs above, some appear to have a temp sensor and output. Would chosing one of those make the discussion moot?

**Craig** · #14 (**permalink**) 01-03-2008, 04:17 PM

I don't think so, it's listed as an additional sensor.

Temperature has already been taken into consideration in the air mass calculation by the MAF. It cannot be re-used by the ECU.

Unless the signal conditioner actually converts mass to flow (which would also require the temperature).

Again, just the way I see it.

**Razzo rosso** · #15 (**permalink**) 01-03-2008, 04:22 PM

Hi Stefano

You are probably right, but the calibration of the temp sensor may differ between AFM and MAF. I simply don't know and haven't been able find out. As Craig says, it may not be important anyway, but an ambient air temp change from 10 - 40 deg celcius makes about a 10% difference in total measured oxygen supply.

The R4 software from Split Second doesn't account for that variable in a 3D map.

Can someone help on this?
Regards

Simon