ECM upgrade (1227730) for stock 2.8 (Page 48/107) Darth Fiero JAN 25, 01:41 PM quote Originally posted by Pyrthian: you can run DIS with a Fiero ECM No you can't. The code mask used in the Fiero ECMs is set up to interface with distributors only. DIS systems have different timing reference points and spark dwell times which aren't 100% compatible with distributor based systems. If you want to run DIS, then you will need to be running the 7730 or other DIS-compatible ECM. -ryan Pyrthian JAN 25, 02:03 PM quote Originally posted by Darth Fiero: No you can't. The code mask used in the Fiero ECMs is set up to interface with distributors only. DIS systems have different timing reference points and spark dwell times which aren't 100% compatible with distributor based systems. If you want to run DIS, then you will need to be running the 7730 or other DIS-compatible ECM. -ryan bummer. it sure looked like it sofar. I was basing on the amazing consistancy I have been seeing in the different setups I have been looking at, while wiring in my 7730. especially the 3.1 Camaro, which is dist based, using what looks like a classic ignition module, running on the 7730. I was thinking the backward compatibility for that might also be a forward compatibility for us. Will JAN 25, 02:07 PM You can run a distributor engine using the 7730 and appropriate code mask (like the $8D), or you can change code masks (say, to the $A1) and run a DIS engine with the 7730 Pyrthian JAN 25, 02:17 PM quote Originally posted by Will: You can run a distributor engine using the 7730 and appropriate code mask (like the $8D), or you can change code masks (say, to the $A1) and run a DIS engine with the 7730 yup - I was just assuming the actual signals were as consistant as everything else. but, I guess I should have looked into the part numbers for 7730 igntion modules vs Fiero ignition modules before saying anything. because by looking at the schematics - the DIS module was just an outgrowth of the igntion module. and, with GM being super nice about consistancy....or - to lazy to redesign , assumed the the dist referance & EST would be the same. because that is the only feed from the ECM. lou_dias JAN 25, 03:11 PM Don't DIS engines fire on the exhaust stroke too for emissions purposes? That's why there are 3 coil packs with 2 plugs on them. Is it 1+4, 2+5 and 3+6? That way when #4 fire on combustion stroke, #1 fires on exhaust stroke and vice versa... Pyrthian JAN 25, 03:19 PM quote Originally posted by lou_dias: Don't DIS engines fire on the exhaust stroke too for emissions purposes? That's why there are 3 coil packs with 2 plugs on them. Is it 1+4, 2+5 and 3+6? That way when #4 fire on combustion stroke, #1 fires on exhaust stroke and vice versa... not for emmision purposes - but, because its an easier design. it just happens to help emisions also. instead of having 1 coil for each cyl, there is one coil for each pair of opposing cyls. the spark plug wires are connected to each end of the one coil. so, when it fires the one coil, it sparks 2 wires. it is also easier on the coil. and keeps the plugs cleaner. Will JAN 25, 03:45 PM quote Originally posted by Pyrthian: yup - I was just assuming the actual signals were as consistant as everything else. but, I guess I should have looked into the part numbers for 7730 igntion modules vs Fiero ignition modules before saying anything. because by looking at the schematics - the DIS module was just an outgrowth of the igntion module. and, with GM being super nice about consistancy....or - to lazy to redesign , assumed the the dist referance & EST would be the same. because that is the only feed from the ECM. The signals serve the same purpose, but as was stated above, the timing is different. Pyrthian JAN 25, 04:07 PM quote Originally posted by Will: The signals serve the same purpose, but as was stated above, the timing is different. while I believe Darth - I am still digging on my own to see what the actual difference is. From what I have seen on the MegaSquirt site, the is no difference. But - MegaSquirt is also designed to handle either also. the timing is handled my the "module" in each. its the "adavnce" which comes from the ECM. on the white wire. that is the only thing that comes from the ECM. the timing advance. Will JAN 25, 07:28 PM But the ECM modulates the coil signal relative to the reference pulses provided by the module... Pyrthian JAN 26, 12:01 PM quote Originally posted by Will: But the ECM modulates the coil signal relative to the reference pulses provided by the module... yes, and again - where I am just assuming compatibity between the 2 systems. the one coming from the pick-up coil, and the one coming from the crank trigger. both read in the ignition module. and, this is where I see the problem - the crank trigger has a 7th pulse - 10* off of TDC #1. I dunno if the dist referance is a raw signal of 7 pulses or a signal of 6 pulses created by the module. I guess just hooking up and oscilliscope to the white wire & the a 2nd pick-up on the purple/white wire would answer this instantly. but, after doing more looking around - that 7th pulse is the why the Fiero ECM wont work. looking at the megasquirt info some more - I see the ECM receives the 7th pulse - which means 2 things: 1> the Fiero ECM would be mighty confused by the 7th pulse 2> the DIS enabled ECM has a clue as to when TDC #1 is - unlike the Fiero ECM. oh - another reason it wont work - them referance pulses on the Fiero are genarated by the pick-up coil - which twists with timing adjustments, while the crank trigger is 100% fixed. anyways - luckily - swapping in the 7730 is way easy sofar anyways. the re-use of the Fiero EGR solenoid wires to carry the knock & fan controls means the additional wiring is super easy & accessable.