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temp *2

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

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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.
Right.

But a fixed value wouldn't allow for cold starts specially in colder climates.
So you need a temp sensor.
But then temp would be in the equation twice so you need a constant value.
:rolleyes:
But a fixed value wouldn't allow for cold starts specially in colder climates.
So you need a temp sensor.
But then temp would be in the equation twice so you need a constant value.
:rolleyes:
 

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Discussion Starter #23
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
 

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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
 

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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.
 

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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?
The thing is that air temp changes a lot while driving. Well, not the air temp, but the temperature of the air being injested into the engine.

On a 70F day, if you sit and idle for 10 min, you'll see inlet air temps above 150F, and as soon as you start to drive, it will drop to 100F pretty quickly.

If you have the a/c on, which is another heat source- you can see even higher temps going into the engine.

It's not just about warming up, but about driving all the time.

If you can find a place to put it in, do it. Or even better, find a wire sensor that has an integrated temp sensor.

Eric
 

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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.
 

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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..
 

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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?
 

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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?
Yes, that looks like a temp sensor.

On a similar note- in all of the time I've been a calibrator, I've never seen a temp sensor have a different calibration- they are all the same thing- a simple thermistor. The only difference between a air temp sensor and a water temp sensor is that the water sensor has a metal jacket fully around the sensing bulb....

Eric
 

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Good to hear they are all the same too. That at least eliminates more calibration. I'll have enough to do with using my own MAF.

Any easy way to test my old sensor? Certain resistance at room temperature, higher resistance sticking it in the oven, never zero, never infinity? Or never above a certain value?
 

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G'Day Stefano,

See pic.


Eric, just to prove an exception to every rule, I have a sensor here from a Renault (I think) which is 300ohm at 29°C (and it's 5:40am :eek: on it's way to 40°C again :eek::eek:).


Edit: If you need something to convert °C to °F (and **** near anything to anything) I use convert, it's free.
 

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Pin 1 of AFM to pin 30 of Motronic ECU

Hi

Can anyone tell me the purpose of pin 1 of the air flow meter (0 280 202 202) from a series 4 Spider that connects to pin 30 of the Motronic ECU?

The diagrams from the manual are below.

Regards and thanks.

Simon
 

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G'Day Simon,

From (failing) memory it's the CO adjustment pot. It's not used on the TS in closed loop and should be about 2.5V in open loop modes.

Will confirm later if no other replies.
 

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2.5 volts

Hi Craig

Thanks for the very quick reply. By the look of the circuit diagram, the ~ 2.5 volt signal is constant, no matter whether when the AFM is open or closed - or am I reading the circuit diagram incorrectly? It seems a little strange to go to all that trouble to create a constant 2.5V input.

With regards to switching from an AFM to a MAF such as discussed in this thread, does that mean a 2.5 volt signal should be created to tell the ECU to behave in open loop. Easy to do, but is it necessary?

Thank you very much for the advice.

Simon
 

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Simon,

It's an emissions adjustment (brass screw under cap on AFM), CO at idle I think, measured at tailpipe.

2.5V is an approximation which probably should be simulated when replacing the AFM (but only Bosch really knows ;) ).
 

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"On catalyst equipped models ... "

Found this ...

CO pot
The CO pot mixture adjuster is a potentiometer that allows small changes to be made to the idle CO. A 5.0 volt reference voltage is applied to the sensor and connected to the AFS earth return circuit. The third wire is the CO pot signal. As the CO pot adjustment screw is turned the change in resistance returns a voltage signal to the ECU that will result in a change in CO. The CO pot adjustment only affects idle CO. Datum position is usually 2.50 volts. On catalyst equipped models, the CO pot has no effect and the CO is thus non-adjustable. :confused:

... at this site. www.opel-scan.ru/files/Opel_MotronicML4.1.pdf
 
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