165 MAF to newer style MAF...
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From: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
Car: 87 Formula T-Top, 87 Formula HT
Engine: 5.1L TPI, 5.0L TPI
Transmission: 700R4, M5
Axle/Gears: Sag 3.73, B&W 3.45
165 MAF to newer style MAF...
Back story:
I was having problems with my 95 Riv SC and one of the potential problems was the MAF, I checked it out at my Delco dealer and the MAF was only $125 (after discount). What struck me was the MAF was NOT in a tube like the MAF from my 87 Formula with the 165 ECM... Basicaly the maf is retained by 3 screws and it has a 1/2" nub that goes into the air stream at the Throttle body.
It got me thinking, Would it be possible to take this newer style MAF and convert it to be used with the old style 165 ECM. From what I know the signal is FM for the 95 Riv and apparently so is the signal from my original MAF, but I am not sure if the signal is different.
I understand the principal of how a MAF works, a wire is heated and as moving air cools the wire it changes the conductivity of the wire, sending the signal back to the ECM. I guess always assumed that the output signal was a voltage (like a TPS), since the input voltage into the 165 MAF was 5V (same as the 95 Riv), but I was unaware that the output signal of the MAF was a FM signal which the ECM decodes.
Has anyone tried something like this, or is it hopeless...
John
I was having problems with my 95 Riv SC and one of the potential problems was the MAF, I checked it out at my Delco dealer and the MAF was only $125 (after discount). What struck me was the MAF was NOT in a tube like the MAF from my 87 Formula with the 165 ECM... Basicaly the maf is retained by 3 screws and it has a 1/2" nub that goes into the air stream at the Throttle body.
It got me thinking, Would it be possible to take this newer style MAF and convert it to be used with the old style 165 ECM. From what I know the signal is FM for the 95 Riv and apparently so is the signal from my original MAF, but I am not sure if the signal is different.
I understand the principal of how a MAF works, a wire is heated and as moving air cools the wire it changes the conductivity of the wire, sending the signal back to the ECM. I guess always assumed that the output signal was a voltage (like a TPS), since the input voltage into the 165 MAF was 5V (same as the 95 Riv), but I was unaware that the output signal of the MAF was a FM signal which the ECM decodes.
Has anyone tried something like this, or is it hopeless...
John
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From: Moorestown, NJ
Car: 88 Camaro SC
Engine: SFI'd 350
Transmission: TKO 500
Axle/Gears: 9-bolt w/ 3.23's
The FM signal is likely up to around 12 kHz with that later model probe style MAF. AFAIK, the PCMs use a pulse counter and a timer capture to read in the high frequency signal. Also, the signal is a series of short pulses, so this can create some issues.
Its possible to use a cheap DIY converter. I did this with a simple IC circuit, and it works, but you really have to do some work to tune it, or use a $200 dollar digital converter. The DIY one requres careful tuning of the circuit to balance time lag and ripple voltages. Using the frequency directly works much better, but this is impossible with a 165. Im doing this with a TBI PCM, and the MAF works very well. The later LS1 MAFs have a very fast response time, and the high frequency signal encodes alot more information. Its definatly a step up from the bosch ones.
Edit: do a search on the TBI board for 'MAF TBI'. That should bring it up.
Its possible to use a cheap DIY converter. I did this with a simple IC circuit, and it works, but you really have to do some work to tune it, or use a $200 dollar digital converter. The DIY one requres careful tuning of the circuit to balance time lag and ripple voltages. Using the frequency directly works much better, but this is impossible with a 165. Im doing this with a TBI PCM, and the MAF works very well. The later LS1 MAFs have a very fast response time, and the high frequency signal encodes alot more information. Its definatly a step up from the bosch ones.
Edit: do a search on the TBI board for 'MAF TBI'. That should bring it up.
Last edited by dimented24x7; Oct 30, 2006 at 12:18 PM.
Thread Starter
Moderator
Joined: Mar 2001
Posts: 14,298
Likes: 197
From: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
Car: 87 Formula T-Top, 87 Formula HT
Engine: 5.1L TPI, 5.0L TPI
Transmission: 700R4, M5
Axle/Gears: Sag 3.73, B&W 3.45
thanks for the tip.
John
John
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