I am thinking about the best placement for the air temp sensor as well (anyone?). My plan is to cut a section of tubing out of my Perrin cold pipe about 12" upstream from the BOV and mount my MAF here. The cut out section of pipe will then fill the gap left in my Injen Intake. I'll be running an MPI with extra injectors so I need to mount these before the TB as well. Soo ... air temp sensor in Intake, loose or somehow mounted in cold pipe (yikes, I'm thinking boost leak issues)?
MAF relocated
- Thread starter sniper9
- Start date
I got a spare MAF with a lifetime warranty from al local junkyard I found on www.car-part.com . I think it cost me $65. As far as the IAT, if you don't want it dangling around, then just find a way to mount it somewhere near your air filter. With zip ties or whatever.Notorious_V.I.C said:
I have a wideband and relocating the MAF did not lean me out with only the stock ECU. AFAIK, the MAF is a hot-wire type, which means it heats a thin wire to a certain degree and sees how much cooling effect the airflow has on it. Denser air will have a greater cooling effect, so I think the added pressure is mostly accounted for in that sensor. But since the IAT will not be seeing the same temps as the MAF, it could theoretically skew the calculations. In the end, it's up to you if you think it's worth it. Many people have done it and none have had any problems from what I've seen.
Notorious_V.I.C said:
When I relocated the MAF, it leaned a little but that was in comparison to the stock position and the reason was because of boost leaks. Basically it leaned it for the greater good but it wasn't too lean at all. Also if you compare the AFC maps between the one I have posted and the stocksuper map, the corrections are truely not that dramatic.
Several people have their MAF relocated and none have reported any problems that I am aware of.
I have been running this setup for atleasat 15000 and it was by far the best thing I ever did before I bought the AFC.
Bala de Plata said:
I have been on these forums for several years, and although I like you guys a lot, sometimes we quibble over the small stuff LOL!!!
IAT's have always been proported to be this miracle secret. I remember when I had my first car back in 1997; people were taking the IAT and moving it to their grills on thier NA cars and thought that they were gaining horsepower! I admitted, I tried it too
All an IAT does is provide an insignificant input the the ECU. The ECU uses the IAT in conjunction with the EGR and the ECT to determine whether or not it needs to pull or advance timing. Generally, the IAT provides the most impact during starting. The ECU will assume that it is a cold start and advance the timing if the IAT and the ECT are within 15 degrees F of each other. After the ECU deetermines that the car is warmed up it relys mostly on the ECT and EGR. The result of the IAT is usually rather miniscule but if you disconnect it, the ECU gets really pissed.Note: IAT locations are like Brittney Spears' singing career; it just doesn't matter!
Place it somewhere in the intake tract. Best place is to tuck it under the filter. Don't put it after the turbo. You will have to take extra precautions to ensure that there are no boost leaks, and even if you do the extra work of ensuring that you have a good seal; in the end... see note above.
peepsalot said:
Bingo, the density of the air is not going to change how the MAF registers the volume as severely as described above. It really comes down to the temp difference between the air when the IAT messured it and to when the MAF registers the air.
http://en.wikipedia.org/wiki/Mass_airflow_sensor
genius said:I have been on these forums for several years, and although I like you guys a lot, sometimes we quibble over the small stuff LOL!!!
IAT's have always been proported to be this miracle secret. I remember when I had my first car back in 1997; people were taking the IAT and moving it to their grills on thier NA cars and thought that they were gaining horsepower! I admitted, I tried it too
Note: IAT locations are like Brittney Spears' singing career; it just doesn't matter!
Place it somewhere in the intake tract. Best place is to tuck it under the filter. Don't put it after the turbo. You will have to take extra precautions to ensure that there are no boost leaks, and even if you do the extra work of ensuring that you have a good seal; in the end... see note above.
Thanks! This helps me determine what I'll do - which is leave the IAT in the spot designed for it in the Injen intake.
I am suprised keeping the IAT on the intake is not causing more problems for people. Has anybody moved it along with the MAF to the charge pipe? As far as the density is concerned, the MAF deals with different air densities under normal operation. Alltitude, ambient temperature, etc will change the air density. Also consider that the air densities would fluctuate at the stock location anyway so ...
- :
- MP5T / 944
Notorious_V.I.C said:
Three years and running strong..
jlindbo said:
Like I said towards the bottom of this thread.... The IAT location is like Brittney Spears' singing career; it just doesn't matter.
The ECU has very little regard to the IAT readings except during a cold start. Even if you move it to a colder location, the ECU might advance timing but after a few hundred miles of seeing the ECT and the IAT consistantly disagree, the ECU would just learn around it anyways.
Also, one quick comment about air density; density is essentially, air pressure divided by temperature (with a few other constants factored in). In order to have any real impact on density, at X altitude, the temperature would have to fluctuate by more than about ~15 degrees C.
The only device that is affected by changes in density is the MAF. The ECU doesn't know or care about density, but if the air is denser it will cause the MAF to produce a higher count to the ECU. This in turn will increase fuel injector time but does not affect timing.
My point is that the ECU doesn't make air density calulations at all; it isn't as smart as some of us give it credit for LOL! The IAT is not affected by density only heat and its input has very little impact on drivability.
i disagree with the IAT not doing much. i put mine to the cold side charge pipe and noticed a huge change. the engine was much smoother and it pulled harder on the bottom end.
byohndspeed said:
I bet if you put it on the dyno, there wouldn't be much of a difference. Our ass dynos have been known to be wrong. LOL!
How cold is your cold pipe? I mean seriously, I know we have intercoolers, but the cold pipe is still a little warm. Mine is actually kinda hot.
The only reason I can see for it working on the bottom end is that the ECU is advancing the timing until the IAT starts seeing the heated air from the turbo. Have you read your spark plugs lately? Too much advanced timing over long periods of time is not good.
I am happy you are happy; but still, it just can't be worth it. I bet if you hung it out next to your grill on the bumper you would get the same results...
genius said:
I am pretty sure the MAF would always use the IAT to determine what the air temp is so that the cooling effect it should have can be determined. A lot of the time they are the same unit. It would seem to me seperating them and feeding the MAF air that is much warmer than the IAT measured would bugger things up way more than density differences.
Right, All I was saying is that there are density flucuations during normal operation, it is not measuing air at atmospheric pressue and even if it was that pressure can change given elavation, air temp etc.
All I am saying is that though moving the MAF puts it in an air density range that it was not specifly designed to run at, that it is not a major issue as the cooling properties of the denser air will still cause the MAF to register a proper weight.
my cold pipe is hardly ever warm. i not saying that i got alot of hp from it. the biggest thing i noticed was the engine was just alot smoother. as for beeing wourth it, i have about $3 in parts and about 30 minutes in time. as for my plugs, i just changed them and they looked good.
jlindbo said:
As always; I respect everyone's inputs and all of your points are duly noted... except this one LOL!
Truthfully; I can answer this without a shadow of doubt. Although the IAT and MAF sensors are usually located in the same house and temperature does have some effect on the MAF and although in the MSP, the IAT and MAF share the same wiring harness... they are not related for this make and model.
For those members that don't know; allow me to shed some light...
There are MAFs out there that do accept an input from the IAT by receiving an input from the IAT and then use that voltage to counter-act the MAF sensor reading but Mazda was not that intelligent.
There are also MAFs out there that have a heated wire next to an ambient temp wire and the MAF calculates the difference between the two and sends the composite signal, but Mazda wasn't keen on that one either.
The MSP MAF is the lowest ranking of the bunch. It uses a filament that is heated to a constant 200 F (hence the term hot-wire). When air passes over the wire, it cools down and then draws more current to reheat back to 200. It can respond to temperature changes and re-stablize the wire temp in less than 5 milli seconds. The MAF then sends a signal back to the ECU ranging from .1 to 5V DC which is a mirror slope of the current draw on the filiment. (As the filiment draws more current to stablize the 200 degree mark, the MAF will produce a voltage climbing towards 5V). The ECU uses this voltage to directly determine injector squirt time.
The MAF has 2 inputs and one output. One ground, one 12 V input and one 5 V out. The 5 V out goes to pin 88 on the ECU. The IAT has one input (power) and one output that goes to pin 39. The ECU uses pin 39 mostly during startup and compares that to the coolant temp to see if the car is on a cold start or warm start. During normal driving, it checks the IAT to determine if the timing needs correction. Generally; if the coolant temp is within normal parameters, the ECU shouldn't make an major moves unless the IAT is really out there in comparison.
I hope this info helps other members who are reading have a better understanding of how these things work, and after a quick scan through the list on this thread, I have read and spoken to most of you before and I highly regard all of your opinions and comments.
I know the MAF doesn't take input directly from the IAT, but how are you so sure that the ECU does not use both MAF and IAT in it's air/fuel calculations, without knowing exactly how it was programmed?
And are you sure the hot wire only goes to 200 F? That seems kinda low. I bet you could get temps over that with a heatsoaked stock intercooler and some upped boost. Ideal gas law says temps would be 427 F(pre-intercooler) at 10psi on a 90 F summer day. I wonder what the **** happens when the MAF sees the wire getting hotter than 200 F without aplying any current.
That 427 F is even assuming the turbo is 100% efficient, which it's not, so temps would be higher...
And are you sure the hot wire only goes to 200 F? That seems kinda low. I bet you could get temps over that with a heatsoaked stock intercooler and some upped boost. Ideal gas law says temps would be 427 F(pre-intercooler) at 10psi on a 90 F summer day. I wonder what the **** happens when the MAF sees the wire getting hotter than 200 F without aplying any current.
That 427 F is even assuming the turbo is 100% efficient, which it's not, so temps would be higher...
Last edited:
peepsalot said:
Not so sure on the 427 F figure. Without 'actually' doing the math and taking the loser aproach via http://www.stealth316.com/2-turbotemp.htm (Funny thing is I am a math major ;P), It would be in the ball park of 240 - 290 given an average operating enviroment pre IC with a moderatly efficiant compressor. Even if your IC had a really crappy efficiancy (Anything above 40%) the temps would be under 200F. I also would guess the stock piping would reach its deflection point before 427 F though (I have nothing to back that up other than a general idea of the materials) and lots up people run 8-9 psi on the stock setup (Springing the WG actuator or a MBC). Even if it was 427 F, a IC with an efficiancy similar to the kits we are using would get temps down below 200 F
Last edited:
