Sunny day blues....

eddiehotrod · eddiehotrod's Garage

Hi all

Last year I had an intermittent starting issue with my '84 3.2, which I thought I had solved by replacing my two flywheel sensors and upgrading the head-temp sensor to the two wire version. All has been well until yesterday, when it wouldn't start. Thinking back to all the times that it happened, it seems to be when the car is left all day in the hot sunshine. All I have to do is push the car into the shade, wait 10 minutes and it starts straight up.
What could it be? - It's not related to the DME relay (swapped it before I moved the car into the shade), and surely the heat generated by leaving the car in the sun is nothing compared to the heat generated by running the engine. I guess that only leaves the DME computer, but once the car is started I have no problems. When it was happening last year, there was no spark being generated, so I don't think it's a fuel system issue.
Can anybody help me with ideas? I was just falling in love with this car again, and now this.

xlr8 · 08-07-2004, 05:22 AM

I have soldered my DME board recently for a no start problem like you described.
These are the joints I re-soldered-

They are the joints that connect this transister to the circuit board-

You may need to look for the cracks in bright sunlight, perhaps with a magnifying glass-

You will need to disassemble these plastic supports to remove the circuit board from the base of the box-

I pressed out the center pins of these supports-

Then I squeezed the ends together to slide the support through its hole-

I used a butane powered soldering iron, it lets me grip the iron close to the tip for more precise control, and there is no cord to get in the way.

Be very careful, this assembly is fragile!

Good luck,

v9ff · v9ff's Garage

Those are some awesome detailed pictures of the DME!!!

eddiehotrod · eddiehotrod's Garage

Thanks Russ, I had my suspicions about the DME and you have confirmed my suspicions. Thanks for the detailed reply, I'll open it up next week and let you know how I get on.

Ed

eddiehotrod · eddiehotrod's Garage

Russ, were you just getting intermittent no start problems, or do you think they were linked to the car being left in the heat of the sun?

xlr8 · 08-09-2004, 09:21 AM

Hi Ed,
I had an intermittent starting problem with the 88 cab while it was parked in the garage. I confirmed it was ignition related. I needed the garage space for another project, so I rolled the cab outside where it was sunny. After the car warmed up in the sun, I was able to start it. After it was parked in the shade for a while, it would not start. I suspected the DME computer and was able to confirm this by swapping DMEs with our 89 coupe. The problem moved with the computer. I guess the contacts in the cracked solder joints shifted with the expansion and contraction of the temp changes and made adequate contact intermittently. A couple of times I had experienced a momentary miss while driving that I believe was related to these contacts.

jpnovak · 08-09-2004, 10:45 AM

I don't have a DME in my car but that is a fantastic description of repairing the solder joints on the board. great pics.

eddiehotrod · eddiehotrod's Garage

Well I got the DME out last night, and although I couldn't find anything nearly as conclusive as Russ did, I did find many of what I would call 'dry' solders. Also, somebody has been in there before me - I could see evidence of previous repairs, so I went over those too. It's back in the car and it started OK, so at least I haven't made anything worse. The next really hot day we have over here will hopefully prove if my issue is solved. Special thanks to Russ for his input.