See here for the original issue: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/fun-coil-packs-input-please-339530/

I've now acquired a volt meter, but unfortunately I'm electrically challenged and don't understand it too well. Instructions aren't much help... I've got settings for DCV, ACV, DCA, and ohms? With different stages of numbers for each...

The instructions say to read resistance (ohms, no?), to set it to either ACV or DCV. From this I put the two probes on the metal surface of whatever I'm testing, correct? If I'm doing this correctly, I'm getting 1ohm from each coil pack...which is what I'm supposed to get, right?

The stickers on the packs say 12v, but I couldn't get the meter to read voltage, so I'm guessing I'm just doing it wrong.

Basically, at this point I'm confused as hell. If my packs are testing right, then wtf is the problem?

I tried to arc them to see what was happening.... pull out a plug, stick it back in the wire and try to crank the car, right? No spark from either leading or trailing, if that's the case. Not a damn thing happened.

I'm stumped, and don't know much about electrics/ignition. Any tips?

 

I don't want to be too discouraging, but if you don't have a good basic knowledge of electricity, you're in for a confusing time. Your meter says to set it to volts in order to read ohms? Are you sure? Isn't there an ohms setting? If there is, set it to that and try again. Regarding testing the sparkplugs, you have to have the plug grounded in order to check for spark. Lay the plug on something metal on the engine - The top of the intake manifold will work. The idea is that the metal on the plug, like the threads, has to be touching metal that is grounded (connected to the negative terminal of the battery.) Start with that and then get back to us.

 

Excellent, thank you. I believe I was setting the plugs on the rubber top of the strut towers... ha.

 

DCV- direct current, volts
ACV- alternating current, volts (household electricity)
DCa- direct current amps
ACa- alteranting current amps

The different numbers are the threshold of the multimeter. Setting it for say 1 miliamp threshold when you plan on shoving 10amps through it, is bad. Just as setting it to read on 1/10th volt increments is bad if you're measuring 500 or so volts. Pretty obvious stuff there.

Ohms is a measure of resistance, not votlage. Take another look at the multimeter. Sometimes they can be confusing in their settings. You can check the resistance of the coil pack, but in doing so, you are not checking the voltage. (mind you output voltage of the coil pack is what-- 40,000 volts?)

Anyhow, since you probably already knew everything I just said... I can concur on the plugger's needing engine ground.

 

Ok, here's another thought, probably slightly far-fetched, but nonetheless....

The plugs are all covered in oil. Is it possible there's enough oil in the plug wells that they just can't spark anymore? I did clean up the plugs but if the wells are still nasty... would that have anything to do with it?

 

Yes, an oil film will play havoc with connections...

Do a search for "basic electrical troubleshooting for the rx7" I wrote a while back...It should make things just a bit clearer for you...For now remember the golden meter rule- for resistance readings, all power must be off...

 

Ok, well... I put the plugs on metal and neither of them sparked when I tried to turn it over.

Can't be a good sign. checked all fuses again, they're all fine.

Does this mean both my coil packs are gone?

 

OK, since you're allergic to a meter, let's keep it simple- does the main relay click when the key is turned? It's the big one behind the trailing coil pack, bolted to the side wall there, near the clutch master cyl...

 

Yes. The car will do everything but actually start. Motor spins freely and fine.

 

Did you pull all of your plugs and clean 'em out real good? Also need to get as much oil as you can off of the plug threads in the rotor housings (don't drop anything down in there!).

Next thing I would do is read out my CAS coils, and check the CAS connectors (one near the CAS, the other under the brake master cylinder)...Set the meter to resistance (ohms), turn off all the power on the car, disconnect the CAS plug, and read the 2 coils out in pairs, turn the CAS plug so the keyway points up, then read the 2 pins on the left with the 2 meter probes, then the ones on the right. You should get somewhere around 160 ohms, give or take 40 ohms, each coil...

 

Yes, plugs have been cleaned out completely. I will clean up the threads in the housing, too.

I'll give a try to what you said. 'Bout to send you a PM...check it.

 

Check the ENGINE fuse inside the car. Third row from the bottom, second or third one from the left.

 

I did. It's fine.

 

check the crank angle sensor, not sure what is the best way to do it but use the ohms on the meter and turn the engine. it should have a "off on" signal. ie it will give a low reading for on and a high reading for off. if it doesnt respond then you gots a bad crank angle sensor. also, if you have the patients, check the ignition SWITCH. sometimes the contacts get worn slap out! oh and get some new plugs...

i hope that helped a little bit.

how long did you have those plugs in there? if you havent had em in too long and there coverd in oil then you may have a faulty turbo ontop of all that.

pm me when you read this..

-chris

 

The motor in the car is all but blown, I'm not worried about it if it is a bad turbo or anything like that. The coolant seals are gone and it's at 204k stock.... if it's spewing oil all over the place, that's fine. It's earned the right to do so by now.

I have the FSM now and have located the specs for the CAS and everything else, so the troubleshooting continues.....

 

Wayne,

The funny thing is if you do a search on "basic electrical troubleshooting for the rx7" all I find is you saying do a search on "basic electrical troubleshooting for the rx7"...

Can you point us all to the actual writeup? Maybe supply the link to us?

Mike B
89 Ragtop

 

Guys, I tried another tact and found Wayne88N/A's thread.

It's at:

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/basic-electrical-troubleshooting-rx-7-a-321278/

 

Thanks, Healeyguy, I'm an old fart and am trying to catch up with the computer proficiency you younger guys seem to have been born with, lol...I think I've finally gotten the hang of posting links now, though, so you guys won't have to go through this again

 

I hate to say it kid, but you're not as old a fart as me. I'm probably one of the oldest here at the site. I've got 10 years on you. December 1955

 

Which means you're wiser (with age comes wisdom)

And thanks for calling me kid, made me feel good, lol...

Did the writeup help you guys any? I know one of these days I need to do something on how to read the Mazda schematics with ease...

 

October 1955 here, Healeyguy. Stickgoat - If the "motor's all but blown," as you say, why put the effort into it? Blown coolant seals, 240k miles,...Yikes. Time for an engine swap.

 

Thank goodness there are other old guys around.

I was getting worried that all there were here were 15 yr olds getting an Rx7 for their 1st cars.

Mine was a 62 Cadillac ragtop that the top never went down when it was sunny and couldn't get the top back up when it rained. Wait a minute, that's what this evil Rx7 is doing to me this week too (Deva Vu?)...

Mike B
89 Ragtop

 

There are several of us "older guys" here... Old enough to have bought a FC new.

And I still worry about the 15 (or even 18) year olds getting an RX-7 for a first car... too much car for 90% of them. Kids driving cars as old as they are...

 

FC new? Mark, you are young...

I had gone thru 3 new Rx7s before the FC was released. I bought my 1st Rx7 Sept 1978. I was told by the dealer if I wanted to see one the 1st year, just learn to love the color yellow ...

It's funny you bring up the 15/18 thing. I just cornered a guy this past weekend that has had a 87 SE sitting in his yard undriven for the last 2 1/2 years. He told me he bought it for his son who was a senior in high school and decidedd against giving to him when he heard the insurance bill was going to be $2800/yr...

The really sad thing is the car is rotting away and the guy is one of these "I'll get it running someday" and looking at his yard and the other derelict cars he has, he never will...

Mike B
88 Ragtop

 

Ah my first RX-7 was also a Yellow '79 SA, but I bought it a couple years used (in 82).