Midnight 85

I'm having ignition module problems, my '85 is completely changed over to the small cap hei with external coil, all of it is Davis brand. i just had to replace another ignition module, the one that went bad was only in the car 2 weeks and couldn't have had 500 miles on it. I have the wiring done exactly as it is supposed to be so I don't think it is the car itself. I'd like to hear TRUE stories that you yourself have experienced with this type of failure no matter what the brand is. Please, no opinions, I'm looking for something I can follow up on before I change ignition systems. I think i can rule out underhood heat because I have a toledo pro hood on the car and it is vented nicely at the back.

jv9999

Are you putting heat sink compound under the module? If you are, it's likely switching too much current. Perhaps a bad coil or maybe your alternator is over charging (voltage too high).

Midnight 85

I use the heat sink compound sparingly, just a even coat of it, the alternator is usually at 13.9 to 14.1 with the higher reading only after starting and turning on headlights. As far as coil output, possible, and worth checking into. FWIW it is also Davis. Thanks for your input.

Kubs

I just put a new DUI small cap HEI in my race car because the off brand small cap HEI that I bought years ago was making my timing very erratic. Its only been in for a few days and just a spin around the block so I cannot comment on longevity. I have an Accel coil. I can report back after the weekend. I will be running it hard this weekend.

You can test the coil resistance to see if it is still good. Put the leads on the + and - plug connectors and then from + to the large terminal. Check with DUI for the two resistance values and see if they are in spec.

WVZR-1

You're using whose module for service? Brand and part#

Midnight 85

I am using the Davis module, not sure of the number right now but it is the DYNA-MOD and I think it is the only one they make for this particular distributor.

WVZR-1

Take the discussion directly to DUI then and I'd think the vendor you purchased from wouldn't have a problem with a refund/replacement.

How many modules have you been through? I'm guessing this wasn't the first.

Midnight 85

I'm waiting for a response from Davis before I tear into things myself. 3 modules in just over a year, ( maybe 1000 miles) is way out of order.

WVZR-1

This car is also an ECM conversion too I believe. Yes?

Do you have all of the failed modules to hand over to DUI?

Midnight 85

Your definitely right 3 modules in just over a year. I went straight to Davis and have contacted them twice so far and no response. If I don't get something by noon today I'll call them instead of emailing them. I like to try and do this sort of thing by email so I don't miss something I may not catch on the phone. My hearing is poor so for me, reading is better. I bought the complete ignition system from Summit and I am sure they would replace whatever I wanted them to but unless they replace 100% of the components I would still rather see what Davis says and let them decide what they want to send me. I am open to any suggestions from them also just in case I do have some sort of problem with the car. I see about 60-40 mix of good/bad in their customer reviews and it is in their favor.

Midnight 85

Yes, updated ecm to 165 version. I did not keep the first module that failed but I have the second one and the one in the car right now. I see I can buy them from China on fleabay for $6. so maybe I better start buying them in bulk quantities,

69427

An important point!

OP: If the ECM is non-stock, is the dwell time calibration tables correct for the coil being used? Incorrect/excess dwell time just cooks the hell out of the module.

Also, what's the coil turns ratio? A low turns ratio is rather abusive to the module switching transistor.

Midnight 85

Wow! this is great information, I will check with the tuner and see what he has in my tune, I will also check the coil turns but since this is a Davis coil that goes with the Davis distributor I highly doubt that will be incorrect.

Midnight 85

I just fired off an email to Brian at Tuned Performance and asked him to check this information out for me, I'll post what I find out.

383vett

Wow, 3 modules in a year. That's not right. I've been using the Accel performance 7 pin modules for decades with no problems. I have two so if the car is not running right, I'll switch to the other to eliminate the module as being the culprit. I always like to place a phone call when there is an issue. I often get better results than sending emails. It is good to have the computer trail left by emails though.

Midnight 85

Hi Willie, I don't get on here like I used to so I haven't talked to you for a while. I see that bad boy still likes to carry the front wheels. I am hoping to get to the bottom of this mess soon, I won't even take the car out of the garage unless I have a spare module and I am not going to spend another $60.+ on one until I find out what is causing these failures.

Midnight 85

While I am waiting for Brian to get back to me, am I correct in assuming the dwell is in the tune?

WVZR-1

How old is this install? Age & miles?

Years ago I had a similar OE/GM distributor in a GM truck and everyone insisted I had module issues. Hot "no starts" etc. I let a fellow do a module, then warranty another module and I mentioned that I actually doubted a module issue. No one wanted to do a pole piece but I finally talked a fellow into doing the pole piece and there was never another module issue.

Midnight 85

I bought the distributor in July of 2016, I then bought the coil May of 2017. IIRC I bought the coil after the first module failure last year. I very much doubt if I put much over 500 miles on the car since the first module failure because we had nothing but rain here the first 3 months of nice weather. Summit replaced the first module and I bought another one in June for a spare. The Summit replacement died around September 7th give or take a few days, at that time I ordered module number 3 . Module number 2 only lasted two weeks so at this time module #3 is in the distributor. The failures have varied as to how the car was affected the first one just died at a stop sign so the car came home on a flatbed. The second one started acting up while on my way to a cruise night but the car stayed running as long as I gave it gas real easy, if I tried to pass it would just not go. The last module started doing almost the same thing, both times the engine straightened out immediately after a new module was put in. SOrry this is so long but I am trying to leave no gray areas.

EDIT: May I ask what you mean by doing a pole piece?

Midnight 85

I checked and found out what you meant by pole piece and that may be something, the metal cover that is covering the pole piece is moving a little bit, I'm going to pull the cap and take a closer look at it.