Ignition module ground

[8upZR1]

I was looking at the schematic for the LT5 ignition module and saw that it has external and internal grounds. I realized then that the internal ground on my module has not been connected as I have removed the module from under the manifold for troubleshooting and now lay it on the windshield. I have since added an extra ground wire to the heat sink plate to simulate the internal ground, but it has had no positive effect. I was wondering if it is possible to fry the ignition module by cranking the motor without this ground attached. Anybody have a clue?

[Tyler Townsley]

Shipped the dis checker and scope today. Should help answer that question.

Tyler

[8upZR1]

Thankyou Tyler, I will forever be indebted to you. If you are ever in the Thunderbolt/Savannah area and in need of food/shelter/clothing please do not hesitate to ask.

[Tyler Townsley]

There is a pigtail so you can check the module without removing the it. In your case you probably need to pull the module and look at the signal as it comes out of the module before going to the coil. On one of my dis modules the signal looked good until it got to 400 rpm then it became obvious it was bad as the signal lost its uniformity. I just hope it helps.

Tyler

[8upZR1]

I hope so too. At this point I am totally stumped. Ever since this problem started I have removed the module from under the plenum and now I just lay it on the windshield so that I can switch between modules and troubleshoot without hassle. Once the car runs I will find a suitable location and lengthen the harness so that I do not have to mess with the plenum to access the DIS. I cant imagine that both of my modules are broken but if they are I will actually be pleased to know what is causing my problem. At this point I am worried that the modules will check out OK. What then will I do? I have learned from the previous owner that the car has gone through four ECM's. In addition I used to have a problem where the car seemed to run extremely rough and lacked power, but this situation only occured when the motor was cold. Once the engine got to the upper range of the temp gauge it would run great. After I installed a chip the motor never got hot enough that the problem went away so I had to ditch the chip. Nobody I have asked has ever heard of such a problem. Most of the time things get worse as the car heats up, not the other way around. I am thinking maybe this vette is cursed and I will never get everything sorted out properly.

[Tyler Townsley]

4 ECMs? There is wireing problem between the ecm and the dis module. I think you will find the DIS module is bad. You need to use the schematics here and chase out every wire to the end. IE pull the connectors at the ecm and dis and run a continuity test end to end. It almost sound like your ecm in and tach out lines are switched on the dis. This is the major difference between the 88/89 cars and the 90+ cars is that wireing difference. If someone was using a 89 refrence for the wiring or replaced the engine compartment harness with a 89 that would be the problem. After chasing the wireing use the other refrences to make sure you have the right info on the line.

http://www.sirgalahad.org/tyler/misc/90ecm1.jpg
http://www.sirgalahad.org/tyler/misc/90ecm2.jpg
http://www.sirgalahad.org/tyler/misc/90ecm157.jpg
http://www.sirgalahad.org/tyler/misc/90ecm158.jpg
http://www.sirgalahad.org/tyler/misc/90ecm159.jpg
http://www.sirgalahad.org/tyler/misc/90ecm160.jpg
http://www.sirgalahad.org/tyler/misc/90ecm161.jpg

Guess I should have included the ecm breakout box too.

Tyler

[Tilbac]

Good news

[8upZR1]

I have finally had a day of free time and have disassembled the LT5 once again. It gets remarkably easier every time. Anyway I have found the culprit. A true mystery, now solved. I dunno how or when it happened. I cant imagine that I did not notice this the last time I assembled the motor. But here it is.....the F F F F'ing hydraulic followers. 17 of the 32 are locked in a fully extended position. I have put a few in a vice and tried to collapse them, but no luck. They will not budge, not even for a hammer. They are somehow solid, and fully extended. I imagin that most or all of them were on the intake side. I did not pay attention due to some extraordinary circumstances. Normally I would label where they come from but I was interrupted, I then turned the head on its back and they all fell out before my brain could think about it. Oh well, but since I had combustion in the intake manifold I assume that most are from the intake and they held the valves open even when riding on the base circle of the cam. How this happened, I do not know. If a piston hit them I would think that they would be stuck in the retracted position. I remember checking them before I put the motor back the first time and they were fine. I always kept them in a zip lock bag with oil.

So, my question to everyone is this: Does anyone have a set of lifters for sale? Does anyone know specifics about what type of audi lifter will work? I have heard A8 but what year? Intake or Exhaust? Does anyone know what has gone wrong with my set?

[8upZR1]

After consulting with a santeria priestess named Pearla, I have found a solution to my broken lifters. I soaked them in the urine of a virgin overnight and left them in a room full of pennies with silver pieces at the corners.....and what do ya know, they actually do move now. And to think that women dont have a clue. Anyway, the heads are back on and hopefully today will be the last time I need to work on this thing. I will post results.

[tomtom72]

I remember a thread somewhere, here or at CF or CAC, about lifters. Someone determined that the lifters from the Aurora motor were the same size lifter bore. I don't know if this is of any use to your situation.

Good luck with the motor!


Tom