Post '85 MAF sensors backwards compatible??
Le Mans Master
Joined: Jul 2001
Posts: 5,297
Likes: 0
From: Stamford VT
Re: Post '85 MAF sensors backwards compatible?? (dtorc4)
Could I use, say, an '89 MAF sensor on my '85? Thanks. :cheers:
Both MAFs send a different signal to the ECM. I believe that the 85 uses a pulsed signal, and the 86-89 uses a constant signal. I think the 85 works in the newer ones because the 165 ECM has a buffer on the input that can deal with the pulsed signal. How accurate the measured air is, well that I don't know. It's accurate at idle, but I haven't had enough seat time with the auto x-ray to see how it behaves at high rpm.
Using the new style MAF on the 85 computer won't work because that computer is looking for a pulsed input and can't figure out what to do with a constant input.
If Corkvette has tried it with better results than me, I'd be interrested in knowing how. A few of us on thirdgen.org tried it and all had the same results as I did.
I would reccomend buying another 85 style anyway. The 85 MAF has a much thicker wire than the 86+ style and is far more rugged. The 86+ MAFs are terribly unreliable, but the 85s seem not to suffer from as many failures.
Race Director
Joined: Aug 2000
Posts: 11,506
Likes: 4
From: Vancouver,Wa.
Re: Post '85 MAF sensors backwards compatible?? (Jim85IROC)
Could I use, say, an '89 MAF sensor on my '85? Thanks. :cheers: No. I've tried it both ways. I'm using an 85 MAF on my IROC which now has a 165 ECM (86-89 style) and it's working, but before I yanked the original 85 computer I tried the MAF from my 88 GTA and it threw a code.
Both MAFs send a different signal to the ECM. I believe that the 85 uses a pulsed signal, and the 86-89 uses a constant signal. I think the 85 works in the newer ones because the 165 ECM has a buffer on the input that can deal with the pulsed signal. How accurate the measured air is, well that I don't know. It's accurate at idle, but I haven't had enough seat time with the auto x-ray to see how it behaves at high rpm.
Using the new style MAF on the 85 computer won't work because that computer is looking for a pulsed input and can't figure out what to do with a constant input.
If Corkvette has tried it with better results than me, I'd be interrested in knowing how. A few of us on thirdgen.org tried it and all had the same results as I did.
I would reccomend buying another 85 style anyway. The 85 MAF has a much thicker wire than the 86+ style and is far more rugged. The 86+ MAFs are terribly unreliable, but the 85s seem not to suffer from as many failures.
Both MAFs send a different signal to the ECM. I believe that the 85 uses a pulsed signal, and the 86-89 uses a constant signal. I think the 85 works in the newer ones because the 165 ECM has a buffer on the input that can deal with the pulsed signal. How accurate the measured air is, well that I don't know. It's accurate at idle, but I haven't had enough seat time with the auto x-ray to see how it behaves at high rpm.
Using the new style MAF on the 85 computer won't work because that computer is looking for a pulsed input and can't figure out what to do with a constant input.
If Corkvette has tried it with better results than me, I'd be interrested in knowing how. A few of us on thirdgen.org tried it and all had the same results as I did.
I would reccomend buying another 85 style anyway. The 85 MAF has a much thicker wire than the 86+ style and is far more rugged. The 86+ MAFs are terribly unreliable, but the 85s seem not to suffer from as many failures.
Le Mans Master
Joined: Jul 2001
Posts: 5,297
Likes: 0
From: Stamford VT
Re: Post '85 MAF sensors backwards compatible?? (corvette0096)
I learned something today.. :yesnod:
Sometimes it's convenient to have cars from multiple years in the yard. :)
