I went up to the Peterson museum drive last Sunday. Pretty hard drive on the car doing 80MPH/ 4000 RPM all day long keeping up with the ZO6's. on the way back I heard a pop and lost all power. Well after a tow and 2 hrs. at PeP boys it turns out the MSD coil went bad but replaced coil/ rotor and cap. Unable to replace ignition module since all PeP Boys had was a stock unit and the MSD has a different wiring harness connection. Since then there has been a hesitation coming off idle and at WOT. Checked plugs, wires, distributer and timing. Car idles 800 RPM silky smooth with no noticible miss. All plugs are firing did notice all plugs have normal black carbon deposit while #5 has white (hotter?). All wires pass conductivity test and also light up my stud finder. The timing was set at 16 ATDC and I reset it to 12 ATDC as per cam (CC 4X4 Cam with a little more lift/ duration than the performer) . Car has run flawlessly since rebuild 2 years ago and this was it's first "major" trip. Any ideas what is causing the hesitation would be greatly appreciated.

 

David, what kind of carb do you have again?, your hesitation sounds almost like a carb problem - I just wonder if the pop didnt do something to your carb.

Also what would you say to a happy hour this weekend?

 

Eldebrock 600cfm, model 1400, mech secondaries. No blow out valve I think.

Hey I think I know the problem. When i removed the MSD ignition module and realized it had a soldered wiring harness outlet I put it back but may have crossed the input wires.

IF ANYONE OUT THERE CAN PULL THEIR CAP AND TELL ME WHAT COLOR WIRE IS ON THE OUTER EDGE LEADING TO THE IGNITION MODULE I'D BE MUCH APPRECIATIVE.


[Modified by Cali,77,L-82, 12:51 AM 11/23/2002]

 

P.S. I'm refering to the wires leading form the interior of the distributer to the module, not the wires leading out of the module out to the distributer cap.

 

Okay here is what I found. The connector from the magnetic pickup to the ignition module is child prrof i.e. it has different size spades and female connectors so that's not it. It is either the MSD ignition module or the magnetic pickup. Now normally I'd spend $200 and get a whole new distributer and that's why I have $26,000.00 in my 77 while you guys have 14K. So I will attempt a repair.
FROM HAYNES MANUAL
Checking ignition pickup, connect ohmmeter to each terminal of the pickup coil wire and ground to dist. base ohmmeter readings should read infinite resistance. I am using a Radio Shack ohmmeter it has the following functions AC/DC/ DIODE Check / K (ohms I think) and CONT (conductivity?) which one do I use? I used the K function and got O.L. (overload?) I guess that means infinite resistance. Part 2 connect ohmmeter between both terminals of pickup coil. Flex wires by hand to check for intermitent opens. Readings should be one steady value between 500-1500 ohms. I got .815K ohms??? Is .815K mean 815 ohms? I don't know what I'm doing.
If it's the MSD ignition module it cannot be checked for it is a circuit board. i have a stock ignition module but the wiring harness has been removed as the MSD unit has a soldered wiring harness that leads out and up to the cap. Thus I cannot check the module by replacing it with what I have and the MSD is $70 out of SUMMIT and would take a week to arrive and may not be the problem. How do I know whether it is one or the other since I don't know what each one's purpose is? Please review symptoms and tell me what you think.




[Modified by Cali,77,L-82, 5:17 PM 11/23/2002]

 

On a ignition system (non computer) there are two wires which are iside the distributor that connect to the ignition module. (my application the colors are green and white) these wires carry AC voltage (value is at a minimum +.7 on the positive wire and -.7 on the negative wire Key on engine cranking) these voltages are sent to the signal converter within the ignition module to a transistor and to the ignition coil. This is based on a HEI 4 terminal module. Hope this bit of info helps.

 

Tried that and your right but still cannot verify if pickup is bad since I do not know what the values are on this ohmmeter. :rolleyes:

 

Not sure if I can help solve your problem, but "K" is the symbol for 1,000. .815K = 815 ohms. Infinite = 0 ohms. "Cont" is probably a continuity check, sometimes with some sort of audible noise to alert you there is continuity. "OL" might mean meter overload which could happen if you were discharging a capacitor perhaps in the circuitry of your module (reading voltage). Whatever lead you got the "OL" reading on, try again, but first ground this lead to discharge any capacitor which might be in the circuit. Hope this helps?


[Modified by Big Fish, 8:38 PM 11/23/2002]

 

Thanks big fish. What I need is someone to answer what does a module do what does a pick-up coil do and based on the syptoms I gave which do you think it is. SUMMIT has their HI-Performance HEI distributer for $149.00 I'm going that direction if no one can help answer the question.

David

 

My own experience with HEI destributors and modules is they work or they don't work. It is possible something else is causing your hesitation problem, and it is just coincidence that it occured at the same time as your distributor problem. I would certainly rule out everything else before buying a new distributor. Is your accelerator pump up to speed?

 

What's an accelerator pump?
Here's what a pickup coil does, doesn't tell me if that's the problem.

Computerized and Electronic Ignition

In an electronic ignition, a rotating reluctor and magnetic-pickup coil replace the traditional cam, breaker points and condenser in the distributors of cars equipped for electronic ignition. This system reduces the time between tune-ups. The high spots of the reluctor interrupt the magnetic field of the pickup coil and the permanent magnet. These interruptions, or pulses, are transmitted from the pickup to a nearby electronic control unit. There, the pulses signal a transistor to break the low-voltage sub-circuit and release high voltage from the coil to the spark plugs.

 

Hey David, before now I would know nothing about your problem, but unfortunetly I have been messing with my distributor alot lately. I have basically the same IGN setup as you. My advice, it aint an IGN problem.

1. Your ohm readings at you mag pickup sound right, less ohms than a points setup for sure.

2. That coil would either work or not.

Now anything is possible with an MSD box, I am starting to doubt mine myself, but the only time I have seen hesitation problems, it was fuel related.

 

I guess it's off to the shop yet again. :rolleyes: I can't figure it out.

 

If your going to continue to try and keep up with the Z06's, it may be time for a 6 speed.. :yesnod:

 

maybe a vacuum leak perhaps?
just a thought. ::shrug

 

I think the next step I would try it to put a timing light on it and see if you are getting both mechanical and vacuum advance at your distrib. If so sounds like you have carb problems.

YBNormal...drive a vette
www.angelfire.com/al/swhite7/vette.html

 

Quote: What's an accelerator pump?

This is a small piston style fuel pump located in the carb. It gives an extra shot of fuel in the air passage when you mash down the accelerator pedal. I would also check the really simple things first like plugged fuel filter or low fuel pressure. :cheers:

 

Checked the carb out. It's not clogged filter or pressure since I have a glass type filter. I'll also checked mech/ vac advance. I don't know what to look for I mean if you iAN What you suggest? idle then 1000RPM then 2000 and check timing eachncrease RPM the timing mark will move and that has zero to do with vacuum advance.

Still clueless.


[Modified by Cali,77,L-82, 6:12 PM 11/24/2002]

 

Starting to think it is fuel related. Carb is a model 1400 Eldebrock 600cfm mechanical secondary.

 

Symptoms if accelerator pump goes bad?