DIY_EFI Digest Tuesday, July 13 1999 Volume 04 : Number 412 In this issue: Re: DIY_EFI Digest V4 #411 Re: Saab 900T AMM (MAF) Swap Re: DIY_EFI Digest V4 #411 Re: Saab 900T AMM (MAF) Swap See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Tue, 13 Jul 1999 07:28:36 -0400 From: "Charles Brooks" Subject: Re: DIY_EFI Digest V4 #411 True, there were (2) four packs but two bottles mysteriously disapeared before I was able to deliver them ;) Charles Brooks Date: Mon, 12 Jul 1999 16:02:02 -0700 From: "Stegbauer, Michael" Subject: RE: DIY_EFI Digest V4 #407 >> pretty accurate for me . Wouldn't you know it, he wouldn't let me have the > info until I delivered the beer! > I'm afraid I have to doubt the reliability of this info... > Guiness comes in four-packs. ;-) > Mike ------------------------------ Date: Tue, 13 Jul 1999 09:35:33 -0400 From: David Cooley Subject: Re: Saab 900T AMM (MAF) Swap At 05:00 AM 7/13/99 -0400, you wrote: >I've been off this list for some time, but have jumped back on now that >I'm in the middle of a project that has some relevance. > >Specifically, I'm trying to replace the stock Bosch VAF meter in a Merkur >XR4Ti (2.3L Ford Turbo) with the MAF (AMM in Saab verbiage) meter from a >'86 Saab 900T (16v 2.0L Turbo). Brad, If I'm correct, the MAF from the SAAB is a vane air meter (a spring loaded door that swings and turns a pot in relation to the volume of air coming in.). The adjustment is the spring tension on the door. This air meter isn't going to be any plug and play, as it will add a restriction to the intake, more so than the stock MAF, and may be more of a bear to get working than it's worth. Why is it being swapped in the first place? =========================================================== David Cooley N5XMT Internet: N5XMT@xxx.net Packet: N5XMT@xxx. Member #7068 We are Borg... Prepare to be assimilated! =========================================================== ------------------------------ Date: Tue, 13 Jul 1999 11:17:15 EDT From: A70Duster@xxx.com Subject: Re: DIY_EFI Digest V4 #411 << My initial thoughts were that I might get lucky and have a plug-n-play swap (with a little electrical work) since the intake consumptions are fairly close. Even though the Saab MAF has an adjustment screw (What specifically does it adjust?), now I'm thinking this is still not likely since I'm hearing the output curves are different between a MAF and VAF. >> The screw is for idle airflow signal output adjustment. You attach a dwell meter to a connector that goes to the SAAB fuel controller and adjust for a 50% dwell. My 2¢ See ya, Mike ------------------------------ Date: Tue, 13 Jul 1999 09:43:18 -0600 From: "Kevin Yachimec" Subject: Re: Saab 900T AMM (MAF) Swap I had given the idea some thought myself. I have a bunch of 1.9 liter ecm's from the Ford Escort. It also use's a VAF meter to measure the air entering the engine. The problem in switching to a MAF meter is it measuring the mass of the air (temperature and volume in one signal) where a VAF measures volume and temperature ( and volume are separate signals) then ecm calculates the mass of the air. If someone wanted to use a MAF meter in place of a VAF you would have to build a circuit that removes or separates the air temperature part of the mass measurement output by the MAF meter. This isn't that hard to do. The problem is that a MAF meter's output is almost linear where a VAF meter's output is logarithmic. A VAF meter is very good at measuring a small air flow. The circuit that converts mass to volume would have to take this into account. I'm not an expert on op-amp circuits so I run out of knowledge when I got to this part of the circuit. I think you could create a series of curves with different slopes and create a response curve that is very close to the logarithmic output of the VAF meter. Maybe someone else in the group could help out. If you don't want to built your own circuit to do the conversion a company by the name Split Second has a device that does the it for you. http://www.splitsec.com/ A friend purchased one for his 2.2 Ford Probe but had a hell of a time getting it to work smoothly. Kevin Yachimec Cybertech Automation Inc. Edmonton Alberta Canada keviny@xxx.ca > Date: Mon, 12 Jul 1999 20:43:36 -0400 > From: bjanesi@xxx.com > Subject: Saab 900T AMM (MAF) Swap > > I've been off this list for some time, but have jumped back on now that > I'm in the middle of a project that has some relevance. > > Specifically, I'm trying to replace the stock Bosch VAF meter in a Merkur > XR4Ti (2.3L Ford Turbo) with the MAF (AMM in Saab verbiage) meter from a > '86 Saab 900T (16v 2.0L Turbo). > ------------------------------ End of DIY_EFI Digest V4 #412 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. 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