MAF to MAP conversion.

[Supra_GT_R]

as its long weekend ive been goofing around with my cars wiring. it seems that a maf translator may not be needed. map sensor i tested with is a 1 bar off a 2000 cavalier, same with the IAT. as i have a whole auto wreckers of cars to chose from.

with the 7mgte afm, there are 5 wires that come off it. 2 are for the IAT sensor, which is easy to hook up the gm sensor to those 2 wires (doesn't matter wich way appertnly.

the other 3 are sensor ground, sensor power +5, and signal. same as the wire plug on the gm map sensor. after hooking up, i hooked the map sensor the vac line going to the charcoal canistor for a test. car idles fine, but as 0 vac is +5 volts signal from the map i used, car wont boost, just surges from 3000-3500. 1 bar is set so -30 vac is 0v, 0 vac is +5v.

so im hoping that a 3 bar map sensor will fix that problem. after all, both work on the +5v signal, only the afm is rated for vacum, and map is pressure.
on a non turbo, i assume a 1 bar would work fine. later ill try running the map off the intake side of the turbine, see what that does, might be fine to use a 1 bar that way. as the 7m has its own map sensor that kicks in under boost (label says "sensors assy turbo pressure")


wiring for the 7mgte engine afm.

air temp sensor: connect to tha (solid green wire) and e2 (brown)

Map: (color codes are based on the 91 grand prix i cut the plug from)

+5 power (grey wire) to the blue and red wire
GND (black) to e1 ground (brown wire at other end of plug, or e2, doesn't seem to matter)
Signal (green) to light green with red stripe.



this post is open for debate, let me know if you think this will work once i get a 2 or 3 bar map. or if this will never work.

Greg

[MightyAl]

Greg,
If it does work I would be completely surprised and will be the first to buy you a steak dinner. The stock AFM works by frequency change and every MAP sensor I have seen works by voltage change (usually 0-5volts). This is why the MAF-T is out there because every hotwire MAF works by voltage change like a MAP. The MAF-T thusly translates the MAF signal into a frequency change that the TCCS ECU recognizes. Any ECU also needs to know the range of the MAP sensor that it is using so it can calculate air mass that the engine is consuming. MAF and AFM do this directly by measuring all the air that zips past said system so they dont care what the pressure is.

The 7m also does not have a MAP sensor per se. The "sensors assy turbo pressure" sensor you are refering to goes directly to the boost gauge on the cluster and the ECU never sees it. Technically this can never work due to the inherit signals that the MAP sensor sends and the signal the ECU expects are completely and totally different.

[Supra_GT_R]

car runs ok aslong as you dont hit on it and boost. once my boost gauge (which is a faze) hits 0, car starts acting weird. as long as i can stay below 0 vac, car runs and idles alot better than it does with the stock afm. my problem could be that i was tapped into a vac line on a thermal vac switch.

but if it doesnt matter what pressure is, why do they make a 1(0 psi) 2(15 psi max) and 3(30 psi) bar map sensors? you are probably right, but wont stop me from trying. :)


i didn't get to experiment with it much today, been naping :). willd o more this week and keep it updated.

[BillyM]

Nah man.... you're seein it drop into default mappings, probably throwing CEL codes out tha wazoo.

You really have to have a voltage to frequency converter, no way around it, and considering native MAP signal does not correlate to airflow whatsoever, your going to have to use something that knows RPM and is programmable to your engine's flow at different map/rpm's...

No way around it. Physically can not work.

I mean, I would love for this to be true, but it just isn't. ...not even close.

--BillyM

[MightyAl]

Nah man.... you're seein it drop into default mappings, probably throwing CEL codes out tha wazoo.

You really have to have a voltage to frequency converter, no way around it, and considering native MAP signal does not correlate to airflow whatsoever, your going to have to use something that knows RPM and is programmable to your engine's flow at different map/rpm's...

No way around it. Physically can not work.

I mean, I would love for this to be true, but it just isn't. ...not even close.

--BillyM

****Enter Dream Sequence with musical montage****

As incredible as it would be for this to work, it is completely and totally impossible. Kinda like a gay couple trying to conceive. I don't know if this guy is going to listen to our incessent babbling Billy.

[Supra_GT_R]

lool yeah i hear ya. only i dont want to pay the 400 bucks for it though. :(

Greg

[BillyM]

...then pay the $100 for a lex AFM...

...they really dont restrict that much.

...and yet as I say that I roll the new VPC chip around in my hand.

...haha

--BillyM

[MightyAl]

...then pay the $100 for a lex AFM...

...they really dont restrict that much.

...and yet as I say that I roll the new VPC chip around in my hand.

...haha

--BillyM

600+ rwhp has been done on the lex. I hope you got a good deal on that VPC.

[BillyM]

...came installed in the car, so yea.

...the GCC attached to it ain't shabby neither, should be pretty fuckin' bitchin once its done and I get to utilize some of this wideband/data acquisition setup. Hopefully running in a couple of weeks and out of my bay. (just dropped the pipe off at the welder's to mount the BOV flange, will be right at the hot side of the intercooler, it will be SCARY-loud.

--BillyM

[joefoe]

Greg the scary part about this is your car runs better on "limp home" maps then it dose when you have your afm pluged in! Sounds like you got some work to do.

[MightyAl]

...came installed in the car, so yea.

...the GCC attached to it ain't shabby neither, should be pretty fuckin' bitchin once its done and I get to utilize some of this wideband/data acquisition setup. Hopefully running in a couple of weeks and out of my bay. (just dropped the pipe off at the welder's to mount the BOV flange, will be right at the hot side of the intercooler, it will be SCARY-loud.

--BillyM


Good I am glad to see you have the GCC. I have heard that the VPC can run out of adjustment without it. I will be interested to hear your thoughts on it when it is all up and running. I had a buddy that said the VPC would need to be adjusted due to weather changes and I am curious if you see the same thing.

[Supra_GT_R]

Greg the scary part about this is your car runs better on "limp home" maps then it dose when you have your afm pluged in! Sounds like you got some work to do.


my car runs good, its just way to quiet. have done some work to it since you last saw it, namley replaced all my old hard hoses. his week i hope to get my exaust finished and bolted on, the work on better intercooler piping and up my boost again, dont want to blow a hose and fry this turbo like i did last time. my brakes are fixed so im not runnning the "ghetto line lock" as you saw.

Greg

[nikwal]

ööh.. I'm not sure what the question was but the answer might be megasquirt extra?. I built one over a weekend. installed it another weekend on the 5mge (7mgte would be slightly more complicated though). Calculated a default map in the tuning program. It ran fine after very little mapping. Funny thing is i dont even have to use tps, just tha,thw,ig,#10,#20,lambda and map are used so i can switch back to stock ecu in 2minutes if something goes wrong..