OK, long story short I've been fighting with some funny ignition problems for a looooong time now.If my memory serves correctly they started 4 or 5 months after I did the HEI mod. At this point the only link in the system that is more than a year and a half old is my disty (cap and rotor are brand new). I've ironed out nearly every problem and gotten the car running nearly perfectly.... Which seems to be about 80-90% of the time, seemingly randomly the tach will bounce around +or- 600rpms rather rapidly with no real change in the engine note. Before I changed my cap and rotor this would usually cause the car to lurch.
I've hooked my autometer voltage guage onto the coil pos. terminal so I can check it while I'm driving and the voltage seems to go up and down with the tach, always below 12vdc when it happens. When it stops the voltage returns to 13ish. The voltage drop doesn't happen at the battery.
Can anyone think of a reason for this to happen? I think I'll try hooking my voltmeter onto the voltage going into the HEI tonight to see if it's before the whole rig, do the volts to the HEI come straight from the ECU?
SOLVED - Strange Voltage at Coil Pos (+) HEI Mod w/ EXT Coil
SOLVED - Strange Voltage at Coil Pos (+) HEI Mod w/ EXT Coil
Last edited by Jutzi420 on May 11th, 2009, 8:55 pm, edited 1 time in total.
Re: Strange Voltage at Coil Pos (+) HEI Mod w/ EXT Coil
Hello
I have this exact problem too. The tach jumping I mean. I have done the HEI mod and it worked perfectly for a while.
But my biggest problem with it is that sometimes it wont start. Usually after standing for a few days it won't start even if I charge it.
Then maybe it won't start every day for a week or a month then suddenly one day it fires right up like there was never anything wrong.
How can this happen? It's not like it can repair itself I mean. I changed all the HEI and coil related compnents a second time and redid all the wiring.
so there should not be any problems with that.
I did try to pull codes, but I don't think I have this the CEL (the light itself) that's suppose to blink.
If anyone has encountered this problem before all help are greatly appreciated.
I have this exact problem too. The tach jumping I mean. I have done the HEI mod and it worked perfectly for a while.
But my biggest problem with it is that sometimes it wont start. Usually after standing for a few days it won't start even if I charge it.
Then maybe it won't start every day for a week or a month then suddenly one day it fires right up like there was never anything wrong.
How can this happen? It's not like it can repair itself I mean. I changed all the HEI and coil related compnents a second time and redid all the wiring.
so there should not be any problems with that.
I did try to pull codes, but I don't think I have this the CEL (the light itself) that's suppose to blink.
If anyone has encountered this problem before all help are greatly appreciated.
Odds, Norway
Red `93 GS, Stock
Red `93 GS, Stock
Re: Strange Voltage at Coil Pos (+) HEI Mod w/ EXT Coil
I went to hook up my volt meter to the G terminal on the HEI yesterday, and found that there wasn't enough voltage to give a reading. So I checked it with my multimeter and got about 0.7vdc. I then checked the B and C terminals (This is all while the car is running) and got about 13vdc on both, are these readings normal?
If there's someone out there with a properly functioning HEI with an external coil (or without, I'm not sure it matters) could they check on these readings? I wouldn't have thought you should get full voltage on the coil-, and I was pretty sure there should be more voltage at the G terminal.
If there's someone out there with a properly functioning HEI with an external coil (or without, I'm not sure it matters) could they check on these readings? I wouldn't have thought you should get full voltage on the coil-, and I was pretty sure there should be more voltage at the G terminal.
Re: Strange Voltage at Coil Pos (+) HEI Mod w/ EXT Coil
The tach only seems to bounce up and down while the engine is cranking now, but the car randomly bogs down under heavy acceleration. My Air/fuel guage reads heavily towards the rich side mostly. I've pulled my spark plugs, they were black so I cleaned them. Shortly after I got inversion errors on both O2 sensors, so I pulled them and cleaned 'em. Ran excellent for about 15 minutes, the Air/fuel read more balanced, then it began reading really rich and bogging under heavy acceleration.
Re: Strange Voltage at Coil Pos (+) HEI Mod w/ EXT Coil
Well, I'm pretty sure I've solved the problem. Thanks to Barry's new diagrams for the HEI mod in the V6 FAQ.
I had previously had everything hooked up exactly as GroHarlem's diagramhttp://www.clubprotege.com/wil/howto/hei/index.htmhad shown. Instead I cut the ECU trigger wire and the ignitor ground from the distributor and ran the ground to the HEI W terminal. The car has been running great ever since.
I'm not really sure why it helped, I have an external coil and I disabled the internal one. The ECU must still have been getting some kind of mixxed message either through the trigger or the ground. Hope this solves your problem as well odds1.
I had previously had everything hooked up exactly as GroHarlem's diagramhttp://www.clubprotege.com/wil/howto/hei/index.htmhad shown. Instead I cut the ECU trigger wire and the ignitor ground from the distributor and ran the ground to the HEI W terminal. The car has been running great ever since.
I'm not really sure why it helped, I have an external coil and I disabled the internal one. The ECU must still have been getting some kind of mixxed message either through the trigger or the ground. Hope this solves your problem as well odds1.