MAF Sensor Position? (Turbo)
 

Has anyone tried placing the MAF in a different location with a turbo application (Greddy)?

Would this in any way make the vehicle run better?

If so how?

anyone?

There are a few people that have played with a "blow through" arrangement on the MAF.

There is no reason it won't work, but the MAF is very sensitive and it will require a very carefully constructed tube, just like it does for a "draw-through" arrangement.

I don't think its worth the effort.

Too damn sensitive

Actually, if you look at the limited space for a straight tube in the engine bay, then compare it to what you can get with a vertical tube to the intake manifold, you might in fact have more room to play with since the vertical tube actually extends beyond the engine bay as it goes down towards the intercooler. But I haven't measured, and my mind is known to have a distorted sense of reality sometimes :)

wonder what the temp sensor would do to afr in a blow through position ????

Not really. Its just very accurate.
It needs to be if you want the car to run well.

Exactly what you would want it to do, which is why mine is located there.

^^ You running another IAT sensor?

Yes.
I have the IAT from a Mazda KL motor VAF just before the BOV.
It has the same electrical characteristics as the OE RX-8 IAT sensor.

I see...I have one just before the throttle body.

I have a KL one in the garage somewhere..might have to check that out

let me get this straight - you have intercepted the wires from the stock IAT sensor and redirected them to another sensor ?

What is a kl motor ?

KL engine = MX series engines....MX-3 and MX-6 Probe etc.

Likely he had one laying around from his old car projects......

I have a GM sensor that I use on the INTx....

Yes. Didn't I post this up somewhere?

Its a family of V6 motors that Mazda put in several cars in the 90's.
In its 2.5 liter form, it was in the MX-6, 626, 929, Millennia and the Ford Probe.
It was also available as a 1.8 liter (the world's smallest production V6) in the MX-3.
It use a VAF (Vane Air Flow meter), which had a center plunger, instead of a hot-wire like our MAF.

You would have to gut the meter to remove the temperature element.

/\ i missed it if you did . Thanks for that info - just what I needed

did you post a diy for this ?

Jeff...can the IAT be reconfigured in the AP to go with a 0-5v signal? What is the specs on the KL/stock sensor?

I thought I did. Looking for it now...

Yeah, the AP can rescale the IAT to 5v.

The KL sensor has the same curve as the OE IAT.

https://www.rx8club.com/attachment.p...1&d=1229889334

https://www.rx8club.com/attachment.p...1&d=1229889334

That was actually a dumb question ;) OH WELL..THE BRAIN WASN'T WORKING :)

Went to a wreckers and he found something that looks like a large one way check valve - the sensor is embedded inside it . Robbing sob wants $75 for it ...
Do i just hack that to bits to get the sensor out ?

It looks like a 3" diameter pipe with a conical plunger inside on a spring.
You cut the plug out of the housing (cut the housing, not the base of the plug itself.
I'll try to grab some pics this week.

/\ yeah that sounds like what he showed me .
The sensor housing inside is an aerofoil shape - can't think how you got that to seal in your intake tube ?

Here is the part:

https://www.rx8club.com/attachment.p...1&d=1229895241

When you cut it out of the housing along the red line, the connector will come out with a "pistol" shaped probe on the end.

It is sealed to the charge tube by cutting a hole that is shaped like the sensor, gasketing it and than clamping a "door" plate over the flange that remains by cutting the sensor from the housing along the red line.

Wow - this is good info; if you have a DIY I would love to see it.

Barney Style of course; Jeff knows how I feel about wiring...

I guess you're looking at it.
I'll ad info as I can generate it.

ok got it . I presume i should get the plug that comes with the sensor to make the wireing easy .

Wonder if getting a stock rx8 one and cutting that up would be easier .....

I made my own plug (you only use the lower 3 wires).

Please, tell me more?

GM Delco IAT sensor...works well..has fast response time and is easy to install...

Would like to know what MM did wih this left over part from the ford PROBE

Well, it was from an MX-3, but...

You still have the part you need attached to that "left over" part.

you didn't see anything funny there mm ?


anyway i cut out the part ok but the wireing has me beat so far ... can you help with that ....

Bingo. That is the part and that is the way it should look for installation. I'll get you some data on the wiring tomorrow, provided I don't get incarcerated following my court appearance in the morning for a speeding ticket I got a while back.
Maybe the Wickenburg Jail has WiFi.

Yes, I did see the humor in your remark.
However, having spent several years as part of the Probe community, it is my obligation to deflect the never-ending parade of dildo jokes that is part of the Ford Probed ownership experience.

common man - that is the most dildo-ish looking car part i've ever seen . I cracked up when it fell out of the bit i cut up

Indeed. Probably could have hooked it up to a stepper motor and made someone really happy somewhere.

I still have another of those laying around in the garage. Hmm. Project...

/\ you know it has a variable resistor on the other end - im sure there is something that could be done with that - Must think !!!!

burn after reading style?

SERVO!

Exactly. But without the chair.

The "nipple" points into the flow.
That makes the other end the "back"
The three connections closest to the "back" are wired to the three IAT wires on the MAF harness.
I just don't remember off the top of my head what goes where.

/\ i hope you are wrong about that cause i cut the two "back" wires off my plug and assumed the three wires closest to the nipple were the ones to use

pretty sure the two back wires went to that variable resitor .....

I guess I'll have to wait till you get out of Jail - heh - hope the judge is feeling the xmas spirit and goes easy on you ....

Meh. I'll take a look tomorrow. You are probably right.

ok - i figured it all out . Contrary to popular myth , you need to cut the RED wire .
Red wire is 5v supply to temp sensor .
Then tap into (but don't cut black white and black green for your return and earth wires .

Did some logging this afrternoon with new temp sensor in place - seems to work well .
Possibly running richer although that could be the fuel trims adjusting to the new sensor location - not sure yet.


The sensor may not be fast enough to measure turbo heat surges . Either that or my intercooler is working well ....

ambient temp 23C - intake air at start of run 34C - end of run 36C

Can I please get a dumb guy DIY?

which bit do you need info on ? I'm not even 100% sure i got it right although everything seems to be working ok ....

Wires to cut and splice; mouting in the pipe etc.

I think MM may have wanted to do the diy - if not i'll do one and he can pull it to bits .......

"Want"? No. Obligated, maybe.

from another thread - if anyone needs it .

MM - What sort of temp rise are you seeing with your turbo after a run through the gears ?
I'm seeing about 13 deg. above ambient at end of run .

If i went way outside the efficiency curve of the turbo - do you think the sensor would be fast enough to see what was going on ?

Little to none. The outlet side of my intercooler is always at ambient temperature.
(Verified with a fast thermocouple and a laser thermo.)
Good IC, very good turbo.

Probably not. It is not the fastest sensor in the world.
The PCM is not expecting very fast temperature rises on that sensor.

Was about to do a DIY on this but started thinking about what was actually happening here and now I'm not so sure it is such a good idea .

MAF is calculated by the pcm by measuring air velocity and temperature at a set point in the intake .
Any point in the intake will have the same MAF (unless there s a leak somewhere) .
So : it stands to reason , if you measure velocity at one point and temp at a different point where the air is hotter - MAF will not be accurate .
End result will be leaner than ideal ixtures as temp goes up because pcm will compute a lower than actual MAF ........

isn't the IAT sensor in the maf?

There is no problem.