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

[Craig]

Quote:

Originally Posted by Razzo rosso but the calibration of the temp sensor may differ between AFM and MAF.

[Craig]

Ok, I actually went to the Split Second site and had a little read up on these devices ( ARC2-A and PSC1-004).

1/ Neither provides a burn off pulse for hot wire MAF's.

2/ Both devices provide a "temperature" output to the ECU (the installation note for the PSC1-004 state "it will tell the ECU that it is a constant 70°F". This is not the complete story though because it also mentions using a temp sensor for better cold start performance. This is a bit strange as we know that the ECU will vary the mixture based on what it sees at the air temp input. I don't get it.

Wait, a temperature sensor would allow the ECU to use it's cold start sequence.

But it would stuff up the other calculations?

I still don't get it.

[iachella]

Hey John (jungle),

Do you copy this? Will you have another conversation with the folks at Split Second? The AFM of BMW that they are aiming at must have the same ECU or a small variation of it. There must be a logical explanation from them.

I don't mind losing the MAF I bought, it's a used unit I found locally. Well I could use it for a while; it probably will work untill the wire gets too dirty. Then I would have to go through another calibration process, but I would certainly learn a lot about these maps and stuff.

I'm really thinking of trying it soon, in the next few months. I had been in contact with a local BMW guy here that was working on one he claimed would be a low cost conversion. He was eager to try it out on an Alfa when I emailed him about my ECU. I was estimating he would sell his low cost unit for $200-400. He hasn't returned my emails in 8 months and this one is $339.

Say it all can be resolved - one should be able to buy

1) PSC1-004
1) Male pigtail to connect to the MAF and splice to the PSC1-004
1) Bosch Female pigtail to connect to the AFM connector on our harness

The picture of the unit doesn't show the ends of the wires, so I'm assuming they are bare.

[Razzo rosso]

of PSC1-004's ??

[iachella]

Hey, I'm just doing some brainstorming. Could a separate temp sensor be installed somewhere on the intake tract and wired to the the AFM pigtail? This means more parts and more wiring and would defeat some of the plug-n-play aspect of the Split Second attraction.

There is a kit for $30 at the bottom of the page here:

MiataRoadster : Engine Management

[iachella]

But then temp would be in the equation twice, right? Since the MAF is doing that? I guess a constant is what is needed.

[Craig]

Quote:

Originally Posted by iachella Hey, I'm just doing some brainstorming. Could a separate temp sensor be installed somewhere on the intake tract and wired to the the AFM pigtail? This means more parts and more wiring and would defeat some of the plug-n-play aspect of the Split Second attraction. But then temp would be in the equation twice, right? Since the MAF is doing that? I guess a constant is what is needed.

[junglejustice]

OK guys, so I haven't had any time to digest any of this myself yet (still in California with Ron Simons visiting ol' Jes and a few other SoCalers), but here is a response from Mark at Split Second - based on some of our comments and questions to this point...

I directed him to the thread, but he chose to reply to me via email - so I'll just past it below...

Mark says:

"I will try to answer the concerns posted regarding the Split Second AFM to MAF conversion solution.

The PSC1-004 is generally considered to be a better solution than the ARC2-A for AFM to MAF conversion. The PSC1 is more versatile and precise. It is also less expensive. It is also possible to share files among users as an email attachment. If several people are planning to do this conversion, I would encourage them to all use the same MAF sensor. That way, files can be shared that will be based on the same MAF sensor calibration. Both the ARC2-A and the PSC1-004 should be mounted in a location that stays dry and does not get too hot. One typical installation, the wire connections are made to the stock wire harness near the ECU.

The ARC2-A and PSC1-004 are designed to be used with 0-5V MAF sensors. These sensors can be either the hot wire or hot film type. Modern MAF sensors of either type do not require a burn off cycle. We do not support a burn off cycle with either of our products. We do offer a range of different sized MAF sensor that are the hot-wire type. We also offer MAF harnesses. They are 8’ long and have the mating connector for our MAF sensors.

We do recommend an IAT sensor be used for the best performance during the first two minutes after cold start. The IAT sensor will help the ECU go into the cold start map after initial start on a cold day. Other than that there is little difference between running an IAT sensor or using the fixed temp reading provided by the gray wire on the PSC1-004 or ARC2-A. When the coolant temp is in the normal range, the IAT signal has a minor effect on air/fuel ratio."

By the way - his contact info is as follows;

Mark Amarandos
Split Second
1949 E. Deere Ave.
Santa Ana, CA 92705

949-863-1359 - Split Second

[turbolarespider]

Happy New Year, everyone!!!

Interesting thread going on here...

A few comments....

volts to mass air flow conversion- the important thing here is that the voltage that you get out is the same for either system at equal mass air flow going through the sensors. If you can get them to match, it should be a direct drop in. There can be some tweaks, and the more modern the computer, the better it will be at adapting to any errors.

For the temp measurement, there seems to be some mis-understanding how it works. First of all, the flapper valve automatically compensates for air temp without direct measurement, too- it takes a certain mass of air to move the flapper a distance. Second- the hot wire system does not measure air temp at all- it actually heats it a little, and the amount cooling it how it measures air flow anyway. MOST hot wire/hot film systems have a secondary sensor to measure air temp- it's the easiest to package anyway. If you know your "hot" system has it, use it. All of the hot wire sensors use 4 wires for the air flow measurement, and one additional for the air temp.

As for the air temp usage... it's only used in a minor way to decide enrichment- very minor. the engine temp sensor is use a lot more, and even MORE important is the lambda sensor + the amount of airflow measured. Cold engines do run a little richer, but not nearly as much as one might think. Anyway, for flow measurement, there may be a minor tweak to the airflow from the air temp- one of those things that the engineers decide is needed as they work on developing the car. It's pretty minor, even in cold weather, if the engine is warm.

What you are all missing is the most important usage of the air temp- spark control. This is REALLY important, especially if you live in a hot area, like, say, down under... For cold temps, the engine can add more spark up to MBT, and at hot temps, the engine retards the spark to protect from knock (cold air knocks less, hot- more). If you run a constant 70F input, you loose the benefit of cold air, and loose the protection for hot air.

For location- if your sensor has a air temp measurement, use it. If not, somewhere near is good- even in the air box- as long as air moves near it.

Eric

[iachella]

Well I've learned a lot from this thread. I'd visited the Split Second website several times trying to figure out if I could use this and I think I can. Jungle John did a great job contacting them and getting responses and Craig and Eric have brough up great points to understanding the Motronic system (at least for me). (Am I sounding like a meeting moderator, sorry..)

I will probably purchase one next month, as I'm tinkering with a few other things first. I had been in contact with a local BMW guy and micro-electronics wiz who was making just a system. He touted it as a low cost conversion and was eager to test it on my Alfa Motronic system. He was aware that the system would be similar and it would probably work. He hasn't responded to me in over six months. I was estimating his low cost system to be $200-400. Other systems, including a full Split Second kit was in the $700-1000 range, but now after understanding what parts are needed, it looks like $339 is the price for what I need. I really don't need to pursue this guy's project.

I think I'll just start with the MAF I got for $40. Maybe the lack of burnoff will ruin the MAF, but I got it cheap anyway. Maybe I can rig a switch to manually do a burnoff everytime I shut the car off, or just before I start. Anyone know what the burnoff is? 12V for 5 seconds, 10 seconds?

And for air temp, I don't drive the car untill it's warmed up anyway. I always let it idle for at least 10 min, but average 15min. The SF Bay Area is very mild anyway. We rarely go below freezing, maybe during the night 2 or 3 times a year and I'm always garaged. I'm not clear if when Eric is talking about the spark advance, does he mean during that warmup, or when fully hot and driving as well. Can you expand a little more on that, Eric?

That $30 IAT kit seems reasonable too, so that could be added at some point.

I'm sure John will do a little more summarizing from his visit when he gets back from SoCal. But, I'll plan on getting it anyway. I'll of course post often as I haven't tweaked an I/O map since my senior project in EECS over 15 years ago. I loved it, but had to wait 20 minutes to erase those pesky little EPROMS and write the values in HEX. Things are a little bit easier these days with these nice software GUIs.

[turbolarespider]

Quote:

Originally Posted by iachella And for air temp, I don't drive the car untill it's warmed up anyway. I always let it idle for at least 10 min, but average 15min. The SF Bay Area is very mild anyway. We rarely go below freezing, maybe during the night 2 or 3 times a year and I'm always garaged. I'm not clear if when Eric is talking about the spark advance, does he mean during that warmup, or when fully hot and driving as well. Can you expand a little more on that, Eric?

[Craig]

Thanks Eric,

It's great to get clarification from a man who knows what he's talking about.

Some Bosch documentation on air meters (flow or mass) may have lead me astray with over simplified statements re flow V mass.


Stefano, burnoff is 12V for one second each time the engine is shut down.

[brookstroutr]

I have used the SS MAF conversion kits on my Euro BMW M635CSi's for sometime. The kit included the MAF (from a '96 - '00 4.6 ltr Ford Mustang) along with the connector pigtail to the controller. The only sensor necessary to change was the wideband O2 which was included. Back to back AFM vs. MAF yielded an additional 22 rwhp. Throttle response is greatly enhanced and the Euro M88/3 really needed this due to the Bosch M1.1 Motronic not being able to handle the 10.5cr and the US's crappy gas.

I'll eventually go stand alone; when funds allow..

[iachella]

Good to hear some success stories. I take it if you get the kit, you don't have to callibrate it since they know the mapping of the one they supply?

I just found this sensor on an old SAAB aluminum intake pipe in my garage. I think it was from a turbo. Does it look like it might be a temp sensor? The threads are about 9-10 mm across and the flute appears to be about 7-8mm across. Two wires, black and white. Characters on the side: 13E1 and 0116 (works on Alfettas?) How best to test?