ECM upgrade (1227730) for stock 2.8 (Page 49/107) Will JAN 26, 02:25 PM The ECM doesn't get the 7th pulse. The 7th pulse is purely for the benefit of the DIS module so that it knows which coil to fire. The ECM only cares about one reference pulse per ignition event, which is what it gets from the pickup coil in the dizzy. The reference angle, however, is different between the two systems. Darth Fiero JAN 26, 02:41 PM quote Originally posted by Will: The ECM doesn't get the 7th pulse. The 7th pulse is purely for the benefit of the DIS module so that it knows which coil to fire. The ECM only cares about one reference pulse per ignition event, which is what it gets from the pickup coil in the dizzy. The reference angle, however, is different between the two systems. I was just going to add that; but Will beat me to it. The reference angle Will is talking about here is the angle in relation to TDC the sensor reads the pulses from the reluctor wheel. DIS is different than a Distributor; and the computer has to be programmed to know this. As I also said earlier, the dwell (charge) time for the ignition coil(s) differs greatly between single-coil (distributor) and multi-coil (DIS) systems. I don't think the Fiero ECM can be reprogrammed to work with DIS; but even if it could, why would you want to use it when the 7730 ECM is so much better? (ie: faster processing, more memory, more adjustable tables, greater diagnostic capability) -ryan Pyrthian JAN 26, 04:49 PM yup, the Fiero referance twists with the distributer, while the crank trigger is fixed and, yes - the 7730 swap way to easy to NOT use it. Will JAN 26, 10:01 PM quote Originally posted by Darth Fiero: As I also said earlier, the dwell (charge) time for the ignition coil(s) differs greatly between single-coil (distributor) and multi-coil (DIS) systems. I thought that the DIS brick handled the dwell for the DIS coils, since dwell for them is greater than one spark interval, unlike the dizzy system. In the dizzy system, one signal from the ECM can control both dwell and spark timing (module charges coil when timing signal goes high, sparks when timing signal goes low). In the DIS, each coil is charging for multiple ignition events before required to deliver a spark, so one signal can't control both... hence I thought that the DIS module handled dwell. Is this not the case? Darth Fiero JAN 27, 01:32 AM quote Originally posted by Will: I thought that the DIS brick handled the dwell for the DIS coils, since dwell for them is greater than one spark interval, unlike the dizzy system. In the dizzy system, one signal from the ECM can control both dwell and spark timing (module charges coil when timing signal goes high, sparks when timing signal goes low). In the DIS, each coil is charging for multiple ignition events before required to deliver a spark, so one signal can't control both... hence I thought that the DIS module handled dwell. Is this not the case? I didn't think spark dwell would have been handled by the computer either until I got into some of the programming used in OBD1.5 and OBD2 systems. There are quite a few tables in there for spark dwell time in these newer systems. I haven't found any in the code masks that are used in the 7730 ECM but they are in there for OBD-2 operating systems that use the same ignition module/coil pack (3100 & 3400). But then again the dwell time could also just be a fixed value in DIS-compatible code masks; something written directly into the operating system and not the calibration. Pyrthian JAN 27, 05:00 PM quote Originally posted by Will: I thought that the DIS brick handled the dwell for the DIS coils, since dwell for them is greater than one spark interval, unlike the dizzy system. In the dizzy system, one signal from the ECM can control both dwell and spark timing (module charges coil when timing signal goes high, sparks when timing signal goes low). In the DIS, each coil is charging for multiple ignition events before required to deliver a spark, so one signal can't control both... hence I thought that the DIS module handled dwell. Is this not the case? me too. but, the reason I thought that was because awhile, the Fiero store sold some "performance" ignition modules, and one of the changes they made in them was the dwell. and, being the DIS module & the Distributer igntion module do the same job, I expected the dwell to be controlled on the DIS module. rjblaze JAN 27, 05:12 PM Someone from the 60*V6 forum just replied to a question I had about the external crank trigger working with our 2.8's and he/she responded that it might work not due to our Fiero pulleys being like a RWD and different than a FWD setup? Pyrthian JAN 28, 09:22 AM quote Originally posted by rjblaze: Someone from the 60*V6 forum just replied to a question I had about the external crank trigger working with our 2.8's and he/she responded that it might work not due to our Fiero pulleys being like a RWD and different than a FWD setup? I guess that would depend on how they mount. The keyway on the crank is the same, and, I expect that is what is used for alignment. but, the actual pulleys are different, as is the timing cover. Pyrthian JAN 30, 11:21 AM quote Originally posted by Darth Fiero: Just use the twisted pair of wires as-is. Most of the time this is what I find on 3.1 DIS systems; no shield wire. -ryan any special rules for the twisted pair? I have 2 connectors, with tails, and just made a cable, about 3 foot, and twisted it up. are the solder connections gonna be OK? they dont "twist" very nicely. and, since I am using abandoned Fiero wires, they are of a thicker gauge than the tail wires on the connectors.... Darth Fiero JAN 30, 12:58 PM quote Originally posted by Pyrthian: any special rules for the twisted pair? I have 2 connectors, with tails, and just made a cable, about 3 foot, and twisted it up. are the solder connections gonna be OK? they dont "twist" very nicely. and, since I am using abandoned Fiero wires, they are of a thicker gauge than the tail wires on the connectors.... What I usually do is stick one end of the pair of wires in a vice, and stick the other end into a cordless drill and tighten the chuck down. I then turn on the drill and allow the wires to twist nicely to the just before the point when they try curling up. After you remove the wiring from the drill/vise it may untwist some, but should still have a nice twist. If you don't twist your pair of wires well enough then they can be susceptible to EM interference from the secondary ignition system. -ryan