Konstantin

any one installed a temp sensor on a huntley MAF?
i want to add one in my car and was wondering if Huntley MAF (ARC2) has a sort of temp sensor and this would interferate with the temp sensor I will add. i remeber that Huntley MAF do not has such a sensor but I am not sure how it calculates the temp for cold starts.

Konstantin

Perry 951

It has no sensor, just an output clamp from the ARC-2 that tells the DME it is always 75 degrees.

I added the stock temp sensor from the AFM back into it, properly connected it to the DME, and left the wire from the ARC-2 for the temp clamp disconnected.

Car runs excellent now, and no need to add fuel when cold. (although the coldest I have tried to start it has been 55)

Konstantin

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Perry 951:
<strong>
I added the stock temp sensor from the AFM back into it, properly connected it to the DME, and left the wire from the ARC-2 for the temp clamp disconnected.
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">how did you wired it? did you put it at #4 and #1 pin on the stock AFM conector?

which wire (color) is the one for the temp on the ARC2?

you said the DME thinks it is always 75 ?? what about when teh temp is above 75 degree. i.e. 100 Degree Fahrenheit? does it runs leaner or richer or???

Konstantin

Dan87951

Yea perry im interested in this mod as well. How did you do it? Maybe you can show me at 944 fest since I have a Huntley Stage 3 MAF and the cold start problem.

Bri Bro

The thermistor goes between pins 1 and 4. If the temp is higher then 70, the car will be a little too rich, if it is under 70 it will be a little too lean. Kind of dumb they left out an inexpensive part on such an expensive unit. You can also install a commercial thermistor, I think Danno has one he sells one with his kit.

Danno

I've sold a couple of them for retrofitting earlier MAF kits. No more manual choke needed! All you have to do is drill a 5mm hole in your MAF tubing somewhere near the AFM connector for the sensor. If you hooked your Huntley MAF into the stock wiring, then it's easy enough to remove the clamped signal going into the air-temp line. Then plug the air-temp sensor into the stock AFM connector and that's it.

TT

The air temp sensor on the 944/951 Motronic is used for three basic purposes:

1. Start enrichment

2. Ignition timing modification

3. VAF volume to mass conversion

For the stock 951 (and huntley and AA MAF chips), 2 is zeroed out since the KLR is supposed to handle this function. Putting in a fixed resistor effectively eliminates 3, but leaves Motronic without good info for 1. Putting in the temp sensor gives good info for 1, but now you will run richer at cold temps due to item 3 (about 9% more fuel at 0 degrees F, linear up to 0% at 60 degrees F). Best solution is to add the air temp sensor and make the necessary DME mods to accommodate the MAF (zero out 3).

Konstantin

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by TT:
<strong> Best solution is to add the air temp sensor and make the necessary DME mods to accommodate the MAF (zero out 3).</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">ok but what are the necessary DME mods to accommodate the MAF??
which wire is the one for teh temp sensoron the DME? color?

Konstantin

TT

VAF connector:

Pin 1 - Air Temp Sensor (+) - Green wire
Pin 4 - Air Temp Sensor (-) Ground - Yellow/Red

Danno should be able to hook you up with a specific chip with volume conversion disabled (tell him its table FI Mod(AirTemp)).

Danno

The air-temp sensor is part of an internal voltage-divider that measures current. So you have to use both pins through the sensor. Also on TT's three points, you also need to quantify the amount of fuel that's adjusted. Fuel-adjustments based upon air-density (temp) #3 is relatively minor and is fully compensated to 14.7:1 in the MAF sensor itself. Thus the need to remove it from the chip or else you'll get double-compensation. But fuel-enrichment beyond 14.7 for cold-starts (#1 above) is much more significant as far as additional fuel added.

Perry 951

I have some pics of it, and will post late tonight. Anyone know if it is polarity dependant? The sensor itself had tan wires with no markings on it, so I was not aware that it needed to be wired one way or another. Typically, thermistors do not need proper polarity. I have not switched the wires to see if it runs different.

Dan87951

Wow amazing the knowledge you guys have. I bet you guys can build a 951 from the the bare unibody and not even look at a manual?! Yea.... some day I'll be that good! <img border="0" title="" alt="[Wink]" src="wink.gif" />

Danno

" Anyone know if it is polarity dependant?... Typically, thermistors do not need proper polarity."

Doesn't matter which way you hook it up, the resistance is the same. As I recall, you removed the fixed air-temp signal from the MAF and restored the factory air-temp wiring out to the AFM connector on your car right?

Perry 951

Danno.. exactly what I did. I did not think it was polarity dependant, since all it outputs is resistance.

So far so good. Once I got the car tuned, I have not had to touch the ARC-2. Ran it from temps in the 50's, all the way to temps in the 90's. Before, I alwys had to add fuel on start up, then take it back once the motor was about 150 degrees.

Konstantin

I think I found all infos I need here
<a href="http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=18;t=000814;p=3" target="_blank">http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=18;t=000814;p=3</a>
more Infos than I wanted. What a pity than the "big" tuners could not solve the Problem and we have to solve it by our selfs.

Konstantin