951and944S

In defense of all of the tuners, I'd like to add, that, there are no tuners that I am familiar with that hid any information from potential buyers.

If you browsed the websites, and veiwed the systems, surely, the buyer is responsible to gain as much information, before mking the purchase.

Both, SFR and Huntley, as far as I know, have complete ARC installation procedures and wire assignments.

Both of these "tuners" have phone numbers and emails, welcoming any questions or technical assistance right there at the site.

In use of this site, I have helped some listers, and have been helped by some listers, and personally, am glad to be associated with a place with so many informative people, including, being able to converse with the actual people who make "the goods".
I'm not "down" with the bashing, though, and when one tuner makes a "claim" about another, I'd like some proof presented, for educated end users to make a conclusion of their own.

$1550, or whatever, is a fair price to whoever is willing to purchase a system for that price, let's not blame the tuners.
I get sort of peeved, when people compare "no name" MAF's to the research and development that SFR and Huntley, also Lindsey, put into this stuff. A generic, fits all, MAF, may be OK for some, yeah, if you want to hunt down clamps, purocil, wiring schematics, and above all, support....!
Comparing apples to oranges, is like buying "replica wheels" IMO
I can't speak for the others quality, but those who haven't seen the polished products that Tim at SFR does, with expert welding that's virtually invisible, cannot comment that a generic MAF with a MAC Mixture control, compare to a complete SFR kit, with ARC, all clamps, hose, hardware, 944 SPECIFIC instructions SS inlet pipes, K&N filter, tech support and the like. Hell, an ARC alone sells for more $ than the whole generic kit..?

Sorry for the length, and I don't mean to offend ANYONE, I, am among the users here with issues, concerning idle and cold start, so I'll pay close attention. If someone here makes the attempt, and disproves the claims that a temp input is not necessary, maybe the BIG 3 will send out an upgrade to all the people who purchased the kits, without one.

Cheers

aka 951

Of course the temp input is neccesary - it varies both the timing and fuel delivery. Scary huh?

951and944S

Yeah, we're aware of the input AKA, but the word sensor was used, also, the necessity of a variable input is in question, and why a simple sensor in the inlet tract could be used, to reference changes in temperature, as supplied to terminal 22 to the DME box..
Does anyone know, if the feul mix, changes by the DME for temperature are infinite as opposed to say three preset values, like for cold, normal, and hot, to be vague.
This would weigh heavily on the importance for me at least, since I'm at sea level, in almost daily tropical climate.

rage2

[quote]Originally posted by 951and944S:
<strong>I get sort of peeved, when people compare "no name" MAF's to the research and development that SFR and Huntley, also Lindsey, put into this stuff. A generic, fits all, MAF, may be OK for some, yeah, if you want to hunt down clamps, purocil, wiring schematics, and above all, support....!
Comparing apples to oranges, is like buying "replica wheels" IMO
I can't speak for the others quality, but those who haven't seen the polished products that Tim at SFR does, with expert welding that's virtually invisible, cannot comment that a generic MAF with a MAC Mixture control, compare to a complete SFR kit, with ARC, all clamps, hose, hardware, 944 SPECIFIC instructions SS inlet pipes, K&N filter, tech support and the like. Hell, an ARC alone sells for more $ than the whole generic kit..?</strong><hr></blockquote>

I don't think price or quality was ever being questioned here. I've seen stuff built by Huntley and SFR, and they look great. I myself am a happy Huntley Racing customer.

This whole thread dealt with an issue that affected both generic MAF's and Huntley MAFs (I didn't see anyone with SFR MAF's or Lindsey MAF's posting yet). I think all of us here are trying to get an answer to the question that will benefit everybody on this board. Personally, I don't even use a MAF conversion on my car, but I enjoy the technical aspects of these mods, and have enough spare time to try and help others, while gaining new knowledge at the same time.

The Big 3 all seems to have different point of views to the cold start/idle issue, which made things even more confusing. Let's hope we can all work together and get some answers to this issue.

rage2

[quote]Originally posted by 951and944S:
<strong>Does anyone know, if the feul mix, changes by the DME for temperature are infinite as opposed to say three preset values, like for cold, normal, and hot, to be vague.</strong><hr></blockquote>

When I played with a motronic EEPROM editor a few years back, I remember the fuel map to be a 3D map of load and RPM. Load is a function of airflow and temperature, so with a fixed temerature setting as AKA951 suggests, there would be no temperature correction.

However, to my understanding, MAF measures air mass, meaning the amount of O2 molecules that pass through the wire, so it should be "compensated" for temperature and humidity. So technically speaking, it should NOT need any correction (thus a fixed temperature resistance sent to the DME), and the signal from the MAF sensor can simply be used as a Load signal.

That's all fine and dandy, but VAF to MAF conversion folks (not just 951's) are still experiencing cold start roughness. Another interesting note, is that Ford, Bosch, Hitachi, and many other MAF sensor makers are now integrating inlet temperature into their MAF units as a 6 wire solution, meaning that an inlet temperature is useful for *something*. Maybe the MAF sensors aren't accurate at cold temperatures, and a secondary temp sensor is used for corrections at low temperatures? If that's the case, you can't wire a temperature sensor to DME #22, because once the MAF heats up you will be running rich (DME calculates load from MAF and temperature settings regardless of what the temerature is). If that's the case, the ARC2 will need to modify the DME#22 signal from a temp sensor only at cold temperatures.

I'm making a lot of assumptions here based on some research I did tonight (http://www.google.com, researcher's best friend). Hopefully someone with greater knowledge than me can shed some more light...

Danno you here? =)

dlr944

[quote]951and944S says: I get sort of peeved, when people compare "no name" MAF's to the research and development that SFR and Huntley, also Lindsey, put into this stuff. A generic, fits all, MAF, may be OK for some, yeah, if you want to hunt down clamps, purocil, wiring schematics, and above all, support....!
Comparing apples to oranges, is like buying "replica wheels" IMO
<hr></blockquote>

Look.... No one has compared "no name" MAF's to R&D that SFR, Huntley, and Lindsey have designed. Not once in this post have I ever mentioned who I purchased my MAF from ... it's just not important. What is important is why some of us are experiencing cool start issues with the ARC 2 and MAF. Perhaps, we have some problem which is not related to the installation of the MAF or perhaps it has something to do with the ARC 2 suppling a fixed resistance to the DME #22 terminal? So I am not sure what your "PEEVED" about?

I going to agree with Rage2's response that "all of us here are trying to get an answer to the question that will benefit everybody on this board." It's great to see support and suggestions from people who don't even own an ARC 2/MAF like Rage2.

I've ordered an equivalent bosch temp. sensor and I am crossing my fingers that this will resolve my cool start issue; it seem's logical given the research that I've gathered. However, it may do nothing in the end but it's certainly worth a try.

TCarrera

Lets see if we can string this out a little more,
I have never driven a Huntley or SFR MAF so I can't make a comment on their cold weather problems. I have spoken with many of our customers that said the problem does exist.
All I can tell you about is that Lindsey Racings unit has a temp sensor and the damn thing works in all weather conditions. Last week Dave drove his street car with our system on it, it was below 32 that morning, he said it started right up and drove off with no problems what-so-ever!
Our system performs without having to make adjustments to the enrichment control, not unless you have made an upgrade to your car and you need to change the mixture.
If Porsche put this sensor in their MAF systems on the 928's and other new models running hot wire technology, they think it is necessary. That's why incorporated it into our system.
Authority really has the problem, they don't even give you the ability to change the fuel setting if you need to, they program a nominal temp value into their software and unless the air temp is what that value is, guess what, it's not going to run like it could.
Mike at LR

rage2

[quote]Originally posted by TCarrera:
<strong>Authority really has the problem, they don't even give you the ability to change the fuel setting if you need to, they program a nominal temp value into their software and unless the air temp is what that value is, guess what, it's not going to run like it could.
Mike at LR</strong><hr></blockquote>

Thanks for answering Mike. Autothority, I totally forgot about them! Now, my question to you is this... is the temperature fuel compenstation that you perform on your MAF kit over the entire temperature range, or just a small range (such as when cold)? Trying to find out if my theory of MAF being inaccurate when cold is correct.

Also, what's a 944 GT3 that you mention in your signature? =)

Huntley Racing

The center of this discussion is over why we do not run a temp sensor and LR does (SFR has just copied our kit but with the original ARC2-A). By converting to MAF from AFM you have to take a few things into account:
One - The MAF automatically compensates for pressure changes
Two - The MAF automatically compensates for temperature changes.
Three - The AFM needs a pressure sensor to compensate for pressure changes (mounted inside the car).
Four - The AFM needs an air temperature sensor to compensate for temperature changes (mounted inside the AFM).

OK now that that is clear I can describe why temp compesation is not needed and add why altiture compensation is! If you add an air temp sensor to an MAF car you will have double compensation. The MAF sensor will correct for cold temps and the air temps sensor will too. When cold the car will be over rich and when hot it will be over lean. Further by NOT taking into account that the stock altitude sensor (pressure sensor) is still on board and functional you will again get double compensation. So the ARC2 has a REVERSE pressure sensor which re-corrects the signal which was over corrected by the stock sensor. LE has not addressed this issue. One thing that I would like is a complete list of those having the cold start problem and what other componants are on board. Things like chips, cams, vacume at idle, voltage at cold start etc... There will likely be a pattern that develops. I have driven MAF cars in the snow and seen no cold start issue and the great majority of MAF owners do not have it even in the very cold climates. Lets get to the bottom of this! <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />

dlr944

[quote] Huntley response: If you add an air temp sensor to an MAF car you will have double compensation. The MAF sensor will correct for cold temps and the air temps sensor will too. When cold the car will be over rich and when hot it will be over lean. <hr></blockquote>

First thanks for the responses from both Derrek and Lindsey!!!

Derrek you stated that if you add an air temp sensor to a MAF your car will have double compensation. Remember the ARC 2 is still supplying a fixed resistance of 1.5k to 2.0 ohms, which equates to roughly 72F (this can be verified by looking up the resistance vs. temperature of this sensor in the 944 workshop manual). So essentially the DME is now tricked in to thinking it’s warm out. Doesn’t this cause double compensations??? Why even connect the ARC 2 grey wire if the MAF automatically compensates for temperature changes???

Thank!

951and944S

dlr944,

Look (as you put it), I've been involved in several discussions on settings, rich conditions, cold start problems, long before you ever popped up here with your brand new, MAF kit. I purchased mine, when companies started selling them, so as far as drivability goes, I probably have more run time than most here with an MAF.

Secondly, my defense of the tuners that frequent this site, was not directed at you, so why get so defensive..?

My point was, that in THIS thread, some posters were claiming that $1500 was expensive for a MAF kit. Fact is, you cannot compare a generic kit, with a kit from one of the manufacturers listed in the discussion, if for no other reason, technical support comes to mind. A Rolex is expensive too, but an immitation, ain't a Rolex.

While I'd like to discuss the issue with you on a technical level, you prefer to come here with your 20 post of bu!!$h!t,(probably all in this thread) to try and get the tuners to solve the problem wth your "no name" MAF, and pit users of this forum against my post, whom I've conversed with on many topics, by selectivly quoting post that serve your interest.
Hope Derek answered your question for you, so you can cancel your order in time....

Cheers

dlr944

951and944S
Nice comments... let’s just stick to the issues. I have a “brand name” MAF kit (one of the three that was previously mentioned). I just though it was interesting that the ARC 2 feeds a fixed resistance to the DME #22 Temperature Input. As your aware the factory temp. sensor varies the resistance based on the air temperature.

You can check with Split Second regarding the grey wire fixed resistance and you can look up the air temperature sensor resistance vs temp. in the 944 workshop manual. Others have commented on similar cool start issues with the ARC 2. I read Derrek’s post and I appreciate his comments regarding the topic; I am still interested knowing why we connect the grey wire to the DME if the MAF automatically compensates for temperature changes? Doesn’t this cause a double compensation problem?

rage2

[quote]Originally posted by dlr944:
<strong>I am still interested knowing why we connect the grey wire to the DME if the MAF automatically compensates for temperature changes? Doesn’t this cause a double compensation problem?</strong><hr></blockquote>

Since the MAF sensor compensates for temperature, humidity, pressure etc., then the DME can use the MAF signal directly as load. The grey wire sends a fixed "fake" temperature signal so the DME doesn't do any compensations.

As Mike from LR pointed out, all factory MAF cars out there have inlet temperature sensors (recently the MAF manufactures are integrating them inside teh MAF housing). So we know the MAF compensates for temperatures, etc, but we also know inlet temperature is used for something on MAF cars. The question is what?

TT

[quote] Does anyone know, if the feul mix, changes by the DME for temperature are infinite as opposed to say three preset values, like for cold, normal, and hot, to be vague. <hr></blockquote>

The 944/951 air temp correction for the VAF is to linearly enrich the mixture from 12.5% to 0% over a set temperature range (don't remember the exact range offhand).

[quote] Another interesting note, is that Ford, Bosch, Hitachi, and many other MAF sensor makers are now integrating inlet temperature into their MAF units as a 6 wire solution, meaning that an inlet temperature is useful for *something*. Maybe the MAF sensors aren't accurate at cold temperatures, and a secondary temp sensor is used for corrections at low temperatures? If that's the case, you can't wire a temperature sensor to DME #22, because once the MAF heats up you will be running rich (DME calculates load from MAF and temperature settings regardless of what the temerature is). If that's the case, the ARC2 will need to modify the DME#22 signal from a temp sensor only at cold temperatures.
<hr></blockquote>

I too noticed that when doing my MAF investigations. All the GM MAF upgrade kits use an inline modifier on the intake temp sensor to enrich the mixture when a bigger MAF is used on a GM vehicle. If you look at a MAF flow/voltage curve, you'll notice that the bottom end of the curve is very nonlinear. Most engine management systems use 8-bit A/D converters, so the smallest change in MAF output that can be detected is .02 volts (.4%) for a 5 volt system. Most MAFs don't operate over the full voltage range, so subtract say 1 volt from the total range(.5 from the top and .5 from the bottom), so now the DME only has 205 points to play with while measure air flows from hundreds of g/s to thousands of g/s. So at the bottom end of the curve (idle territory) a small change in air flow due to temperature would not be noticed by the DME. All new Bosch MAF sensors have the temp sensor back in the housing, so I believe it was added back to allow for detecting small changes in air temperature while the MAF still compensates for large changes in temperature.

PrerYDoG

So what would be the effect of taking an LR MAF Kit and adding an ARC-2 to it? Would this have the ability to better tune the fuel curve over the RPM band, and still allow for cold start issues to be solved? Knowing that, we would know how adding a temp sensor to other MAF kits with the ARC2 would work. What is the wiring setup for the Lindsey kit anyway? Anyone know that? It seems like we have solution out there, why re-invent the wheel if we can apply current knowledge and technology to the problem?


Further, to the guy from Baton Rouge who's starting a pissing contest, take it some place else. You may have logged more hours than every person on this board combined, but somehow I don't see your experience here as adding anything to this conversation, I further don't see how you could have any cold start problems being where you are.