I need to know the most common reasons why rx7s don't get spark. right off the top of my head I'm thinking triggering device, or bad coil packs...........but its late and I'm super tired and I need to know what yall think.....thanks for your time.

Nick

 

how did you determan no spark? are you not getting spark on all 4 wires?

 

Ive had this happen a couple of times, both after engine swaps, and both were on s4 NAs. The components worked fine when the bad engine was removed(as a whole withi intake and wiring intact) and the new transplanted. Plug it all up and get no spark. I spent 2 days the first time, swapping coils, relays, checking fuses, swapping wires, and the CAS, and checking voltages. Come to find out it was something int he airflow meter. I unplugged the one in the car(that had worked the day before) and the car developed spark, but wouldnt run(obviously, with the afm disconnected). I then hooked up a spare one and it fired right to life. THis happened on 2 seperate cars. I know the 89+ afms are different, but may suffer from teh same fault. Something to try. IF you unplug yours, and check again for spark, just dont expect the car to run with it unplugged. Other than that, ther eis the CAS, coils, and fuses, all of which are pretty much bulletproof and have never failed on me in 30+ FC's.

 

How about a popped EGI fuse? On a 87 its in the engine compartmet, l/h side, black rectangular cover. Or how about the cas plug not fully on. Or ECU plug left off during maint? Or a review of the ignition system http://www.teamfc3s.org/info/article...g.html#signals Or ohm out the wires b/t the cas and the ECU. Sorry, I don't think I've ever had no spark. Hard to believe both the lead and trail coils w/ignitors went **** up at the same time. You checked spark on the lead and trail plugs both. This will bump your post TO THE TOP OF THE LIST.

 

I,ve lost spark twice on an 86'na both times I had burned the wires up .
I finally solved this by buying some quality wire's. it was over about a month one set was autoz-ne other set parts amer-ca. Maybe it'll help.

 

Well I checked everything after work(not everything just coils and wires) they all ohmed out to spec........so I checked the ECU its getting power but.... checked the ground(8.3 MEG OHMS) dang its high so the question is........would it hurt any thing to cut the wire the ECU and take it strait to battery ground? any help would be much appreciated.

Thanks for all your posts,

Nick

 

IF youre worried about the ground, just locate the right one, cut off some insulation, and run a short extension wire directly to the frame, by grinding off the paint with a dremel and bolting it down, the bolts right below the ecu work well, or you can drill a hole and use a sheetmetal screw with a ring terminal. I wouldnt go running wires back to the battery, grounds should be as short as possible in all applications, or else all grounds in the car would run back to the battery. IF your battery-to-chassis connection is good, then the ground will be equivalent anywhere on the chassis.

I dont think this is your problem either. Have you checked all fuses, and fooled with the afm as I described above? ITs usually a fuse or the afm in my experience.

 

OK i'm about to check all the fuses and stuff but I have one more question...........why would there be such high resistance to the ECU I mean there shouldn't be any for the ground. right? once again I really appreaicate all the help
thanks,
nick

 

ok I checked all the fuses and nothing? well I'm going to ground the ecu some where else so if any one has any suggestions I'm willing to listen.........BTW I checked the spark on all four wires..nothing.I'm going to ohm out the CAS and see what the specs are........(the swap is a 91 j spec 13b-T into my 89 TurboII if that helps any...thanks

Nick

 

WHen you did teh swap, did you pull the harness through the firewall, or leave it in the car and disconnect everything on the engine? There was one time, when swapping an engine(I always pull the harness WITH the engine, through the firewall), I didnt have one of the plugs in the pass. kick panel COMPLETELY together, and it wouldnt spark, then I checked and found it hadnt clicked together. There are 2 real big gang plugs, yellow, in the kick panel, that are hard to get at...it was one of those. IF you didnt disconnect all that, then dont worry about it. Tried unplugging the afm plug then turning engine over to see if it sparks yet?

 

I pulled the harness though when I did the swap I'll check those. and I'll try unplugging the AFM...I know I always go back to the ground thing but the only thing that is leading me to the ground is that I have my S-AFC hooked up to the ECU and it doesn't come on when the power is on and its power is coming from the ECU's power and ground so I checked voltage to the ECU and its getting voltage so thats when I checked the ground and its said that the gound wire had 8.3 meg ohms of resistance so thats what was making me think it was the ground (haven't had time to check it....If i'm wrong in my thinking please straiten me out.
I have jet to work so I'll check every thing when I get home

thanks,

nick

 

Well, if you think the ground is a problem, fix it, its not a big deal. You have an 89+ car, so your harness should have a little ground loop for the ecu right where it plugs in, I think it grounds to the body there too. Just find that ground wire, make yourself another ground to the body, grind off any paint or dust, and bolt the sucker down using a good ring terminal. Then there wont be any question. ALso you should probably go out and clean you rbattery terminals, adn run another ground from the battery to the chassis, and maybe one from the chassis to the engine, with good clean connections on each end.

Thats somethign else...you DO have the engine grounded dont you? The large thick *** wire on the driver side starter bolts? IF the engine isnt grounded it will not spark. Unlikely but possible anyway.

IF you ground everything well then that shouldnt be a future concern, and we can concentrate on what else there is the problem.

 

Just sell it to me and be rid of it!

Wish I could do more to help you

When you get it running, let me know. Ill drive on down and we can "run em"

 

i often have trouble with no spark after i have had my coils and ignitors out to work on something else. The coils and ignitors need good ground or else they wont fire. check it, if need be run a earth straight to the mount for the coils/ignitor from the -ve battery lead

 

you can have it for 5k thats what in need to get out of it you can have both motors exhaust, AFC, TT, Blah blah blah.......I'm serious fo real.

Nick

 

Dude! Lemme sell my car! Im serious fo real too dawg!

 

I guess that no spark was a crappy way to start the post. come to find out my fuel pump doesn't come on and I don't get any spark so I it can't be the coils I'm still messing with all this stuff so any help would be appreaciated................sorry but I tried messing with the MAF.........Fuses and every thing else mentioned

Later,

NICK

 

It was the ECU ground....now the beast it running.......Once again Thank you for all your guys help....Merry Christmas

Nick