DiscoClax
12th May 2011, 05:11 PM
Hi all,
Just want to run this past the knowledgeable...
The background: The mech advance in my dizzy died a while ago. I didn't have a replacement so I locked the mech adv and set it to 12deg static. Got another dizzy off eBlag recently and when it arrived it looked new, with no evidence of wear marks on the drive gear, etc. Bewdy. Came with the ignition module on the side already, but no vac adv. :D Looked like it may have been fitted to something, briefly (marks from the clamp-down evident) but otherwise as new. Whilst swapping over the vac advance I fumbled the dizzy, dropping it dead-smack on the new rotor :( and breaking it, naturally :( The shaft still felt OK and all else appeared well with the unit with only the rotor appearing to have copped it. I dug out a new, spare, genuine rotor button, and dropped the dizzy into the old girl, timed it up (12 deg) and all was well. Recently I had replaced the leads (Top-Gun spiral-wound), plugs (NGK BPR6EYs - regapped to 0.8), and had fitted a new genuine cap. After setting it all up the cranking time was higher than before, but I'd fiddled with the idle speed at the same time and just put that down to that.
The problem: Next day drove it. Long crank but then clean idle (both petrol and LPG) and good running. Always start it on petrol and then switch over to gas after a minute or so. Switched it back to petrol for the last few hundred meters (as I always do before parking it) and it seemed to be hunting a bit on over-run but was OK at idle and fine under load.
It has continued to do this ever since (a couple of weeks). Long crank, but then runs OK, however hunts and flares on over-run at low revs (like rolling up to a set of lights, etc - but only on petrol, totally steady on gas).
It was quite tricky to start the morning before last (cold morning), but then ran OK as per normal. Yesterday, in pouring rain, in peak-hour, with a trailer on the back, it just died. Was idling (on gas) and just stopped like you'd turned the key off. Would not restart, on either fuel. Popped the bonnet, checked the vitals, all OK (coil connections, etc) Still nothing. Touched the plastic cover of the ign amp module (mounted to the side of the dizzy) and it was scorchingly hot. Hmmmm. Left it for a few minutes, cleared the fuel system by cranking without fuel on, and then switched it to gas. Fired straight up and didn't miss a beat from then on. Did another couple of hundred kms of city/hwy mix last night without issue.
When getting home, switched it back to petrol, and it would barely run. Three-legged dog style. Had to two-foot it to keep it going.
I'm thinking it's the ignition module/amplifier. But previous experience with electronic ign modules (other vehicles) is that they either work or they don't, no in-between. And I'd guess that the reason it's carrying on when on petrol is that the injectors are firing erratically due to a flakey signal from the coil?
Anyone want to throw in their two-bob's? have I missed something?
It's '94 (serpentine) D1 V8 auto, stock ignition, dual fuel. All bar the dizzy and module were in the car previously and ran fine. The coil windings check out as expected (ie. about 1 Ohm / 7.5 kOhm) and are the same as my spare coil. Nice solid 12V to the coil +ve, too. Throws a continuous, blue spark across a 1/2" air gap from the end of the HT lead when cranking (checked a few days ago). Go figure?
And, before it's suggested, I intend to do the 'BeeUtey upgrade' as soon as possible. Especially as I've located a later-type dizzy with the remote-mounted module in the garage :D Looking for suitable parts now.
Just want to run this past the knowledgeable...
The background: The mech advance in my dizzy died a while ago. I didn't have a replacement so I locked the mech adv and set it to 12deg static. Got another dizzy off eBlag recently and when it arrived it looked new, with no evidence of wear marks on the drive gear, etc. Bewdy. Came with the ignition module on the side already, but no vac adv. :D Looked like it may have been fitted to something, briefly (marks from the clamp-down evident) but otherwise as new. Whilst swapping over the vac advance I fumbled the dizzy, dropping it dead-smack on the new rotor :( and breaking it, naturally :( The shaft still felt OK and all else appeared well with the unit with only the rotor appearing to have copped it. I dug out a new, spare, genuine rotor button, and dropped the dizzy into the old girl, timed it up (12 deg) and all was well. Recently I had replaced the leads (Top-Gun spiral-wound), plugs (NGK BPR6EYs - regapped to 0.8), and had fitted a new genuine cap. After setting it all up the cranking time was higher than before, but I'd fiddled with the idle speed at the same time and just put that down to that.
The problem: Next day drove it. Long crank but then clean idle (both petrol and LPG) and good running. Always start it on petrol and then switch over to gas after a minute or so. Switched it back to petrol for the last few hundred meters (as I always do before parking it) and it seemed to be hunting a bit on over-run but was OK at idle and fine under load.
It has continued to do this ever since (a couple of weeks). Long crank, but then runs OK, however hunts and flares on over-run at low revs (like rolling up to a set of lights, etc - but only on petrol, totally steady on gas).
It was quite tricky to start the morning before last (cold morning), but then ran OK as per normal. Yesterday, in pouring rain, in peak-hour, with a trailer on the back, it just died. Was idling (on gas) and just stopped like you'd turned the key off. Would not restart, on either fuel. Popped the bonnet, checked the vitals, all OK (coil connections, etc) Still nothing. Touched the plastic cover of the ign amp module (mounted to the side of the dizzy) and it was scorchingly hot. Hmmmm. Left it for a few minutes, cleared the fuel system by cranking without fuel on, and then switched it to gas. Fired straight up and didn't miss a beat from then on. Did another couple of hundred kms of city/hwy mix last night without issue.
When getting home, switched it back to petrol, and it would barely run. Three-legged dog style. Had to two-foot it to keep it going.
I'm thinking it's the ignition module/amplifier. But previous experience with electronic ign modules (other vehicles) is that they either work or they don't, no in-between. And I'd guess that the reason it's carrying on when on petrol is that the injectors are firing erratically due to a flakey signal from the coil?
Anyone want to throw in their two-bob's? have I missed something?
It's '94 (serpentine) D1 V8 auto, stock ignition, dual fuel. All bar the dizzy and module were in the car previously and ran fine. The coil windings check out as expected (ie. about 1 Ohm / 7.5 kOhm) and are the same as my spare coil. Nice solid 12V to the coil +ve, too. Throws a continuous, blue spark across a 1/2" air gap from the end of the HT lead when cranking (checked a few days ago). Go figure?
And, before it's suggested, I intend to do the 'BeeUtey upgrade' as soon as possible. Especially as I've located a later-type dizzy with the remote-mounted module in the garage :D Looking for suitable parts now.