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Guest Message by DevFuse
 

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lets talk about MAF's


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23 replies to this topic

#1 WJM

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Posted 11 January 2005 - 10:19 PM

Can i use a 1st gen legacy MAF on an 87+ turbo EA82T setup?

#2 WJM

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Posted 12 January 2005 - 07:22 AM

anyone?

#3 All_talk

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Posted 12 January 2005 - 10:27 AM

While it probably works over the same output voltage range (most likely 0-5VDC), I doubt it shows the same voltage as the stock unit for the same flow, so without reprogramming the ECU I really doubt it would work. Just a guess tho.


Gary

#4 Myxalplyx

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Posted 12 January 2005 - 11:29 AM

While it probably works over the same output voltage range (most likely 0-5VDC), I doubt it shows the same voltage as the stock unit for the same flow, so without reprogramming the ECU I really doubt it would work. Just a guess tho.


Gary

Hrrm, just think of this.

Suppose that for 'x' amount of flow the EA82T shows 2 volts. If you switched to a Legacy Maf and its 2 volts was equal to 'x+20cfm' or something like that, your range of cfm before getting to 4.7 volts or so would be broader. This would broaden your range before hitting fuel cut wouldn't it? :brow: Try it out! If you don't, I know I will someday. Woot!

#5 JWX

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Posted 12 January 2005 - 12:39 PM

try it

#6 RallyKeith

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Posted 12 January 2005 - 01:15 PM

I would only do it if you have a really good EGT sensor and gauge in. If the engine is getting more air than the ECU thinks then it will run lean and you could destroy the motor. I would tend to think that this is the situation you would run into, since the Legacy MAF is setup for a 16 valve 2.2 which moves a good bit more air then our 8 valve 1.8s.

Give it a try if you can, but be careful and listen hard for detonation/pinging.

Keith

#7 All_talk

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Posted 12 January 2005 - 03:21 PM

Hrrm, just think of this.

Suppose that for 'x' amount of flow the EA82T shows 2 volts. If you switched to a Legacy Maf and its 2 volts was equal to 'x+20cfm' or something like that, your range of cfm before getting to 4.7 volts or so would be broader. This would broaden your range before hitting fuel cut wouldn't it? :brow: Try it out! If you don't, I know I will someday. Woot!


Problem is that the ECU would be providing fuel based on the flow (voltage) it sees and would be very lean, if it would run at all.

Gary

#8 Vanislru

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Posted 12 January 2005 - 03:24 PM

Just buy an 86 already ;).

#9 mikie

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Posted 15 January 2005 - 03:50 PM

Can i use a 1st gen legacy MAF on an 87+ turbo EA82T setup?


If the leg MAF sensor works over the same voltage range as the EA82T one *AND* you used the matching legacy injectors it might work. Maybe.

If the leg MAF gives a lower voltage for the same air mass flow, being designed to allow for a heavier-breathing engine, then the ECU would signal a shorter injector pulse. If you used higher CC injectors in theory you would end up injecting the correct amount of fuel, and have more headroom for more power.

#10 Myxalplyx

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Posted 15 January 2005 - 03:59 PM

If the leg MAF sensor works over the same voltage range as the EA82T one *AND* you used the matching legacy injectors it might work. Maybe.

If the leg MAF gives a lower voltage for the same air mass flow, being designed to allow for a heavier-breathing engine, then the ECU would signal a shorter injector pulse. If you used higher CC injectors in theory you would end up injecting the correct amount of fuel, and have more headroom for more power.

This is one approach. Another approach would be to get a RRFPR (Rising Rate Fuel Pressure Regulator). This would help out at wide open throttle (WOT) situations. Around town driving is something else altogether. Perhaps an SAFC would work. I like the Legacy injector idea.

This is going to far though. Can anyone here post what the pinouts are on the Legacy maf sensor? You know, what is ground, what is the hot wire, etc. This would be a starting point to figuring this out. I'll ask around and see if I can post up a pic or something.

If someone has an FSM they can scan, if they could post a pic of EA82Ts maf sensor's pinouts, that would be helpful also. Here's an example of what I'm talking about. This is a scanned pic out of an XT6 FSM. It shows the XT6s maf sensor and what each corresponding wire is/means.

Posted Image

I posted this up in an attempt to use an SVX Maf sensor from this thread:
http://www.xt6.net/f...?t=1862&start=0

Perhaps a note or pic of the voltage range would be helpful as well.

#11 carfreak85

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Posted 15 January 2005 - 04:35 PM

Do the MAF swap then get one of those nifty fuel computers and use it to alter the the signal so it will work. I think that set up would net a few hp if not more.

#12 Myxalplyx

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Posted 28 October 2005 - 05:40 PM

Can i use a 1st gen legacy MAF on an 87+ turbo EA82T setup?


Has anyone tried this yet?

#13 All_talk

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Posted 28 October 2005 - 06:54 PM

Completely different voltage scale output, EA82T is 1v to 12v, the EJ is 0v to 5v, I explored the idea here:

http://bbs.legacycen...af scale output

Gary

#14 Steveman09

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Posted 28 October 2005 - 06:58 PM

Can i use a 1st gen legacy MAF on an 87+ turbo EA82T setup?


No you can't, I've learned allot doing my E-Manage install and the 87 Hotwire MAF is NOT a standard 0-5V MAF its actually a 0-10V system, therefore if you switch to a Standard 0-5V MAF it will run really lean around 3500rpm and up (ive tried it)

Only solution is to use the E-Manage with a Pressure Sensor or a Megasquirt and Elliminate it.

#15 WJM

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Posted 28 October 2005 - 07:11 PM

that means SAFC is out, period.

back to the drawing board.

#16 Steveman09

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Posted 28 October 2005 - 07:12 PM

that means SAFC is out, period.

back to the drawing board.


Yeah I ditched my S-AFC-II Project after I found this out, whenever I got on boost around 10psi it went super lean and engine went PIIING PIIING BAD!

No thanks.

I didn't spend $3k on my engine to blow it up so easy.

#17 WJM

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Posted 28 October 2005 - 07:28 PM

like....totally.

#18 Myxalplyx

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Posted 28 October 2005 - 09:59 PM

No you can't, I've learned allot doing my E-Manage install and the 87 Hotwire MAF is NOT a standard 0-5V MAF its actually a 0-10V system, therefore if you switch to a Standard 0-5V MAF it will run really lean around 3500rpm and up (ive tried it)

Only solution is to use the E-Manage with a Pressure Sensor or a Megasquirt and Elliminate it.


Now this is making sense to me. I'm thinking the XT6 has the 1-12V (or 1-10V) setup as well. I installed an SAFC on my XT6 a while back and reported to the XT6 folks. The car went WAY lean on the top end. This not only happened with my Apexi SAFC but also with my Simple Field Hyper SFC as well. I'll post a dyno plot with Field Hyper fuel controller turned on and turned off in a moment.

The Apexi SAFC unit was printed out and not in a .drf dyno file format so I do not have that to show the results. I was tuning my FWD XT6 at a dragstrip (Cecil County Raceway) that just happened to have a mobile dyno there that night. The results were printed out and those papers are gone.

Edit...actually found my old runs I did with the SAFC at the dragstrip. I scanned the pics and posted them up at XT6.net a while back.

Posted Image


Posted Image

Rest of them:

http://mywebpages.comcast.net/thomasck/DynoRuns/XT6/Old/mini-Dyno3.JPG
http://mywebpages.comcast.net/thomasck/DynoRuns/XT6/Old/mini-Dyno4.JPG
http://mywebpages.comcast.net/thomasck/DynoRuns/XT6/Old/mini-Dyno5.JPG

#19 WJM

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Posted 28 October 2005 - 10:18 PM

Yep...there we have it.

Now...what to use for some fuel control....the stock ECU is evidently VERY good at timing control.

Hmmmmmmmmmmmmm...........

#20 Myxalplyx

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Posted 28 October 2005 - 10:29 PM

Here is the Field Hyper SFC fuel controller turned on vs it being turned off testing on the dyno. Turned on caused the XT6 to go lean on all geards from 1st to gear the higher the rpm went in that gear.

Posted Image

With the SFC turned off, I was testing the affect of fuel pressure being raised/lowered so that is why the two identical lines are red and blue. One setting had a higher fuel pressure than another setting. Fuel was controlled much better with fuel pressure than the SFC.

#21 Myxalplyx

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Posted 28 October 2005 - 11:07 PM

delete

#22 WJM

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Posted 28 October 2005 - 11:13 PM

maybe that 2 means 12 in JDM.

#23 Myxalplyx

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Posted 28 October 2005 - 11:18 PM

maybe that 2 means 12 in JDM.


Nah, I screwed up.

#24 WJM

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Posted 30 October 2005 - 06:12 AM

meh...we all screw up. lol




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