DIY_EFI Digest Wednesday, 30 September 1998 Volume 03 : Number 448 In this issue: VSS- Part 1 solved new to list, FAQ, Bosch DME Re: miss still happening See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Bruce Plecan" Date: Tue, 29 Sep 1998 23:52:09 -0400 Subject: VSS- Part 1 solved OK, this just in and verified. If you are running a 1227730 ecm, from a 90-92 TPI that uses prom aujp, and you want to run a 2000ppm speedo input do the following, Change prom address 0018 from D8 to 98 Then use C-6 as the speedo input. As run on my bench in side beside testing they were +/- 1 mph.. Speed was set, and the the diacom reset and run on the other ecm to compare mph's. 747 to 730. Cheers Bruce Grumpy lost a dime on this bet, and has been in a fit over it (course that's a days wages here). ------------------------------ From: "Steve Iverson" Date: Tue, 29 Sep 1998 21:02:59 -0700 Subject: new to list, FAQ, Bosch DME Hello. I'm new to the list and am looking for any FAQ's that may help me catch up on some of the discussion. In particular, I'm interested in learning more about Bosch's DME. I have Bosch's book already, but am looking for site or tips as to how to go about reprogramming it, and eventually sensor modification. I have a '74 914 with a 1991 911 3.6 liter engine. You can see more details on my car at http://www.cs.hmc.edu/~siverson/914/36/, if you'd like. The engine is stock except for a modified intake (wouldn't fit due to trunk), modified exhaust (racing 914/6 1.75" headers), and a lightweight flywheel. Currently the DME mapping is stock and I don't think it is optimal. The engine will stall sometimes because, I believe, the lightweight flywheel lets it "spin down" too quickly. Furthermore, I think more horsepower could be achieved if the programming was optimized for my less restrictive exhaust. Let me know if you guys have any suggestions or where I can look, or where to start. I have a CS degree, but am anxious to get a little dirty in some of this EE/embedded stuff I know nothing about! - -Steve ------------------------------ From: am018 Date: Wed, 30 Sep 1998 17:30:32 +0100 Subject: Re: miss still happening A couple of things I have come accross in the past that caused hard to track down missfires. Check the main feeds at the back of the alternator --- these sometimes cause bad voltage spikes that cause missfires with electronic systems. Also check the plug lead routing -- separate the leads as much as possible. Andrew F. Gunnesch wrote: > Well, I guess I spoke too soon... the miss is still there, though it > doesn't happen nearly as often as it did before. Perhaps the ignition > module also has an intermittent loose connection in it? > > When the miss is happening on my '89 TPI motor (MAF, '165 ECM, remote > coil distributor, VSS in the transmission), the speedometer jumps up > quite a bit. I'm thinking that it could be one of several things (I > am getting a diacom today for testing to help eliminate possibilities): > > 1) Intermittent loose connection in either the ignition module or > below the spot in the wiring harness that I spliced in (the 4-wire > connector to the distributor) > > 2) Intermittent loose connection in either of the 2 wire connectors > on the coil > > 3) bad ECM > > 4) bad VSS buffer box > > 5) crosstalk (induction, jumping spark, whatever) between one of the > ignition wires and one of the wires that controls the distributor/ > coil operation > > Suggestions on how to proceed? Thanks! > ------------------------------ End of DIY_EFI Digest V3 #448 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".