Finally got rid of the sputtering. It was a little hard to pin down, because it only happened when the engine was cold, and even then only under a mild load and at cretain RPM's.
But I unplugged *everything* from the motor except the CPS, ignition, and injectors, and started it up. Got RPM spikes and cutouts. Figured it had to be some sort of feedback from the ignition system (that's internally fouling the CPS tooth counting). So just on a hunch I rechecked the distributor clocking. Rotated the motor to a pretty advanced position in front of #1 TDC (there's up to 50 some odd degrees of advance in the map) and checked the rotor position. Ahh, a little ahead of the terminal on the crabby cap (the terminals on it are 90 degrees off what a stock cap is, so just sort of eyeballed it on initial assembly). With the rotor off the distributor was able to come up just barely enough to clear the gears (16V thermostat neck overhangs it) and I moved it a tooth ahead. Put it all back together, took it for a drive (engine was cold) and voila, no more RPM spikes, no more sputtering under a mild load at 3000 rpms, drivability improved tremendously. I still have a *very* infrequent little stutter/rpm spike, but it's been doing that pretty much forever, not really much of a problem at all.
So I think that occasionally when the resistance at the plugs went up, that the spark didn't want to jump a small gap in the dist cap, and the coil would then burp a voltage spike back into the LT system? (No change at all between the Blaster 2 coil and the original Bosch coil). Which would then travel backwards through the MSD box (made no difference if I bypassed that), and through the 124 ignition driver (didn't try bypassing that) and back into the MS box, where it caused problemswith the crank sensor reading? Doesn't quite seem right to me, but since that seems to have cured it, I can't imagine what else it could be.
Is it possible to add a diode on the LT wires of the coil? I had to do that on the EBC solenoid, as it clicked on and off (which it does, a lot) it was sending nasty little spikes back up the ground wire to the MS unit. Is it possible to do the same on the coil? Are the spikes the opposite polarity from the LT leads (as is the case with the EBC solenoid)?
Back to doing more tuning with the E85. I've put just under 300 miles on it so far. Chinese GT3076R hasn't blown up yet. However, I am hearing a little chuffling fromt he exhaust manifold, I think that crappy Goatse exhaust manifold gasket I got from FCP may not be holding very well. I may pull the turbo off soon and see what's going on there. Probably should have had the manifold skimmed, I think they said to do that and I sort of never did... *ahem*
But I unplugged *everything* from the motor except the CPS, ignition, and injectors, and started it up. Got RPM spikes and cutouts. Figured it had to be some sort of feedback from the ignition system (that's internally fouling the CPS tooth counting). So just on a hunch I rechecked the distributor clocking. Rotated the motor to a pretty advanced position in front of #1 TDC (there's up to 50 some odd degrees of advance in the map) and checked the rotor position. Ahh, a little ahead of the terminal on the crabby cap (the terminals on it are 90 degrees off what a stock cap is, so just sort of eyeballed it on initial assembly). With the rotor off the distributor was able to come up just barely enough to clear the gears (16V thermostat neck overhangs it) and I moved it a tooth ahead. Put it all back together, took it for a drive (engine was cold) and voila, no more RPM spikes, no more sputtering under a mild load at 3000 rpms, drivability improved tremendously. I still have a *very* infrequent little stutter/rpm spike, but it's been doing that pretty much forever, not really much of a problem at all.
So I think that occasionally when the resistance at the plugs went up, that the spark didn't want to jump a small gap in the dist cap, and the coil would then burp a voltage spike back into the LT system? (No change at all between the Blaster 2 coil and the original Bosch coil). Which would then travel backwards through the MSD box (made no difference if I bypassed that), and through the 124 ignition driver (didn't try bypassing that) and back into the MS box, where it caused problemswith the crank sensor reading? Doesn't quite seem right to me, but since that seems to have cured it, I can't imagine what else it could be.
Is it possible to add a diode on the LT wires of the coil? I had to do that on the EBC solenoid, as it clicked on and off (which it does, a lot) it was sending nasty little spikes back up the ground wire to the MS unit. Is it possible to do the same on the coil? Are the spikes the opposite polarity from the LT leads (as is the case with the EBC solenoid)?
Back to doing more tuning with the E85. I've put just under 300 miles on it so far. Chinese GT3076R hasn't blown up yet. However, I am hearing a little chuffling fromt he exhaust manifold, I think that crappy Goatse exhaust manifold gasket I got from FCP may not be holding very well. I may pull the turbo off soon and see what's going on there. Probably should have had the manifold skimmed, I think they said to do that and I sort of never did... *ahem*
Last edited: