I just bought a 1987 RX-7 (N.A.) on Monday. Fun as hell. But, it looks like I'm having problems with the CPU cold solder points. What I was wondering is if resoldering the CPU will fix all of these problems, or if I have multiple issues:

* Clock Flickers
* Voltmeter guage periodically doesn't work
* Tachometer periodically doesn't work (accompanied by shift light malfunctioning, and sometimes a buzzing noise when the tachometer is barely working and it's reading lower than it should be)

The tachometer thing is new today. It started working a few minutes into the drive though.

 

It's probably bad solder points on the gauges themselves. The clock most definatly, pull the idiot light cluster out and you'll see what I mean. The dash gauges are a little bit more work to get out, but there's an assload of solder points on the back that are usually bad.

 

With the gauges, I'll bet it's the copper contacts that the gauges screw on to. Mine were almost green with oxidation. I cleaned mine with a brightboy abrasive eraser (You can find them at hobby shops. They're used for cleaning slotcar and model railroad track), then sprayed them with bullfrog contact cleaner/protectant. They've been working flawlessly ever since.

 

Yep these wonderful cars and their wonderful wiring. Cold Solder joints for sure, dunno about the gauges though.

 

No re-solding the CPU will not fix any of those problems.

The clock problem requires re-soldering of the clock warning panel, where the plug meets the circuit board. Remember you need to remove the old solder first, then flow new solder in. I also have many of the different models of the clock warning panels already rebuilt on my website, if you don't want to do it yourself.

The volt meter and tachometer are related to poor screw connections on the back of the gauge panel. Remove the screws and put a little conductive grease on the tip and end of the screws and screw them back in.

and inflatablepets you said: I would bet $100, that none of his problems are related to wiring. The wiring in the FC is perfectlly fine. Yes some of the electrical parts have problems with cold solder joints after 10-15 year, but then again so do the electrical part on Lexus, Toyota, Honda, Porsche, Mercedes, etc.

I just don't get how people can think the FC electrical issues are any different than electrical issues on any other 15-20 year old cars.

 

(sighs) I will debate this issue with you again. I HAVE seen melted FC wiring harnesses before. I stand somewhat corrected as I should have said cold solder joints, or electrical isues. Cold solder joints are a specific issue with the manufacturing process. Age does not make a cold solder joint, improper soldering techniques do though. From what I have seen with the soldering issues on these cars is that there was not enough solder on the joints, so they never did make optimum contact to the PCB thereby causing additional resistance. Additional resistance causes more heat thereby causing melted wiring harnesses. I have also seen plenty of these joints crack as well. causing intermittent issues with items like the clock, logicon and other electronics. I also believe that the gauge of wiring on these cars is too small and should have been increased to 18 gauge or so. I still somewhat debate the wiring issues with these cars are more server than most others. I have owned much older cars than the FC that have NEVER had any wiring issues. These include Toyota, Honda, Chevrolet, Ford and Mazda. It seems to me that the issues are most prominent in the FC. I am not as familier with the FB's but I have not heard any of my rotorhead friends complain, or come to me to fix their screwed up wiring.


I can't complain too much as my FC was working perfect except for the intermittent clock which I repaired recently.


Edit: Icemark, I think you took my words out of context. I sort of like these discussions that are held in an intelectual manner. P.S. Don't ban me.

 

Right now, 60% of my cold solder repair work, is coming in from a Toyota/Lexus dealer and mostly 90-96 model parts. I also have rebuilt about a half dozen porsche cruise control brains, (all built by Bosch), and about the same mercedez ones each and every one of them related to cold solder joints. I also have been asked to do FD gauges for the same cold solder joints.

And I can't tell you the number of mid-80s to early 90s Honda ignition controllers that I have seen failed from cold solder joints.

So the cold solder joint thing is by no means a FC only thing.

and I would never ban anyone for a difference of opinion. #1 mods can't ban, #2 its not like you are delibertly trying to falme, provoke or offend anyone.

 

a LOT of the watercooled porsches have cold solder problems like icemark said, even in newer parts that are being made for them. i just had to resolder a DME relay for a 934S that was made in 92

 

I will concede due to the fact that I am not in business to repair automotive electrical problems. Thank you for an intelligent littlt diffrence of opinion there. There are good people on "The Forum". Anyways, to the thread starter, it looks like you have the good info you need to make the repairs and I wish you good luck.