89RedsunGTUs

iTrader: (1)

Hey guys, been fightin this issue for the past week. As i drive fresh in the morning, no CEL and Tach Functions properly. Drive home from work and CEL comes on and Tach shuts down. using my Rtek, it shows me "Trailing Coil Failure" for current errors. once i shut off the car and restart, CEL goes off and Tach work again, but if i have been driving the car with the issue for a while, it only takes a minute for it to fail again.

So, now onto things i've tried...
1: switching coils, worked for a day or so but then same issue. revert back to old coils, worked for a couple days then same issue again.
2: did the Rear hood vent using washers, thinking that if i was heatin up the coils some how it would help. nothing noticable
3: realizing i had possibly pulled out too much fuel, and was over working the coils with a lean mix, i added more fuel and it seemed to prolong it.
4: Wiring, i've looked at the wiring at the connectors and didn't notice anything, but i'm planning on lookin closer.

One thing i noticed, could be coincidental though. CEL came on quicker with Headlights on.

Any ideas you guys can give me a better direction would be awesome. or any expirence would help.

Thanks guys. as usual, i expect this won't take long with you guys on the trail.

HAILERS2

Monitor the voltage of the batt/alt when this happens. See if the problem only happens when the voltage drops under 12vdc. For some unknown reason I came to the conclusion that if batt voltage drops real low, the ECU cuts trail igniton i.e. tach action also. I might be wrong, might be right.

89RedsunGTUs

iTrader: (1)

^^ Thanks, i'll definatly look at the voltage gauge if it happens while driving and see if it drops at all during.

on this note, i do murder batteries alot lmao

89RedsunGTUs

iTrader: (1)

alright, updates

Waited for it to get dark so i could put as much draw on my electrical system as possible. (real reason, i repainted my hood lol)

Drove around and let the car get hot, turned on my Taurus fan, and instantly, CEL no Tach. hmmmm i thought, so i pulled over, shut the car off, switched the fan off again, and turned the car back on. and started moving again. turned the fan back on, and nothing... drove around some more, switched on all the lights, (headlights, Fog lights) and still nothing. mean time i was Datalogging with my Rtek, and Voltage Never dropped below 13.24 the entire run..... so once again i'm back at square one...

1: if it was wiring, wouldn't the problem be more consistant???
2: if in deed it was the coil. everytime, the car got hot. it should fail?

Thanks again guys for adding input, or idea's i greatly appreciate it.

89RedsunGTUs

iTrader: (1)

Update:

finally remembered to bring my DMM home from my shop. monitored the alt while idling, and was getting 13.4 volts, then randomly it would go to 0v, then 8v, then 13v than 4v again, then 13v. so i'm assuming this means the Alternator is going bad.

Now, can i use a S4 TII alt on my S5 Motor? i have a spare alt from my extra TII motor.

Thanks again guys

datz

definatly sounds like the alternator is going bad, but i cant answer the question wether a turbo alt could work but i would think no problem, but i could be wrong on swapping the alt

89RedsunGTUs

iTrader: (1)

aaaannnnd definatly can't use a S4, the plugs are 100% different lol. so now i'm on the hunt for a S5 Alt locally lol

RockLobster

iTrader: (7)

That monstrosity of a VDI intake manifold makes using other alternators a bear on S5 N/A cars.

I would stick with the stock S5 N/A alternator. And yes the S5 TII is different and does not even come close to fitting in the stock location due to the plug being on the back side.

Digi7ech

iTrader: (1)

You have a taurus fan?
YOU NEED AN FD ALTERNATOR!

I bet the taurus is killing your battery and alternator. It pulls serious amps.

As for "totally different wiring", not really.
Although an S4 is extremely weak. Something like 70amps or less.

https://www.rx7club.com/showthread.p...72#post5131072

89RedsunGTUs

iTrader: (1)

lol Thanks Digi.

i've had battery probs since i bought the car. but, i don't doubt the taurus fan surely isn't helping.

do you happen to have a spare FD alt? lol i'm commin back down to phoenix on saturday.

by different, i was talkin bout the connectors. don't feel like cutting wires to downgrade i agree

also, do you agree my alt goin wacky could cause this trailing coil crap?

Digi7ech

iTrader: (1)

not sure, I would assume an improperly initialized/charged coil could possibly not fire.

No extra FD Alt.

RockLobster

iTrader: (7)

Yes it can. But check the trailing coil ground as well.

When i had a bad engine block ground the voltage would drop and the trailing coils would shut off.

thewird

iTrader: (8)

Was this ever fixed? Was it just the alternator?

thewird

pdxrotornewb

iTrader: (2)

I'm curious what the fix was as well. I'm having the same exact problem, and replacing the alt and battery didn't help. I'm still suspecting a bad replacement alternator.

misterstyx69

iTrader: (142)

I had this problem on an Rtek 2.1 and it was due to to the Premix ratio.It kept bogging the Trailing plugs.
when they don't fire your tach doesn't work.

movingim

Were you able to solve this as I'm having the same problem with CEL, and dead tach. There's little consistency and when it does happen I have been able to determine the coil pack does not receive the "trigger" signal to fire the coils....

satch

iTrader: (1)

Having a problem w/both coils or just the trailing?

movingim

Just trailing

satch

iTrader: (1)

Does the CEL spit out a specific code that relates to the trailing coil or does just the CEL come on? How did you determine that the coil was w/o the trigger signal from the ECU? Have you checked the connection to the CAS?

movingim

Hello:

Yes the CEL flashes the code for #1 and the tach goes dead when CEL comes on.
I'm assuming that the trigger signal is cutting out thus the trailing coils not firing. I had the engine running with trailing leads pulled with spare plugs inserted and grounding on the intake manifold. The plugs had good spark then lets say 10 seconds later they would stop firing as if the the power was shut off to the trailing coil/igniter.

Today I started the car and ran it until it was warmed up, everything worked fine, no CEL light or dead tach. I tested voltage from the trailing coil 4pin connector and 2 pin connector and compared to FSM

(2) Pin connector +12v
(4) Pin Connector
1G (B/Y) Ign Switch on 0v and Idle .5v (Timing Signal)
1J (Br/Y) Ign Switch on 4v and Idle 1.9v (Select Signal)
1V (B/G) Ign Switch on .9v and Idle 1v (Confirmation Signal)

So the 1V (B/G) is reading under specs, FSM says "Below 2.0v Ign Switch on and Approx 4.0v at idle.

The next time the trailing coil stops working I will take readings.

I have not checked the CAS.

Other then this intermittent problem the engine runs great! I have tried another used working trailing coil/igniter and same problem persists.

satch

iTrader: (1)

https://www.rx7club.com/2nd-generati...wires-1013741/

Pin 1V should be 1.4 volts while idling as indicated in the link above. Secondly, the coil's igniter must be grounded to the fender by the coil properly being bolted to it and perhaps the grounding is not as it should be so make sure the coil is getting a proper ground. And the timing signal can be measured w/key to on and rotating the alternator pulley which rotates the Main Pulley which then causes the timing signal wire to alternate from 0 volts for most of the time and then to 5 volts very briefly before quickly reverting back to 0 volts. When it comes to the four wire plug you might want to try to clean it and do the same thing for the CAS plug as well.

movingim

The trailing coil stopped working today, enough for me to check with a DVM and determine there is no voltage to terminal 1G at idle which according to my 1990 FSM edition should read 0.8v. Of course I'll start the car tomorrow and the CEL light will be off and the Tach will work for a few days then it will happen again.

Thanks for clarifying the voltage for Pin 1V, I have a 1989 FSM in a electronic format (pdf) and the actual 1990 FSM manual and the voltage is different, maybe a typo? The car is a 1990.

I'm pretty confident that the trailing coil is properly grounded and the (4) pin connector is clean. I'm going to check the CAS.

satch

iTrader: (1)

Make sure that pin 1G is mated properly at the ECU as opposed to having an iffy connection. If this wire were pulled back within its plug at the ECU then it can possibly work sometimes but not at other instances.

Also, when pin 1G has no voltage w/key to on do an ohm test of the wire to confirm whether the wire is grounding out or not. No key necessary for the ohm test (can damage the circuit).

thewird

iTrader: (8)

The coils ground to the chassis btw., not the wiring.

thewird

movingim

Problem fixed!

Four days ago the CEL light came on along with the dead tach. I would restart the car and CEL light would be off and the tach would function, once I pressed the brakes to activate the brake lights, or any other electrical load, the CEL would turn on and the tach would stop functioning this happened consistently.

I cleaned the main ground wire/cable located in the lower left shock tower and the ground wires located under trailing coil, I used a external tooth washer between the ground wire ring terminal and the body, this gave a little more bite, I also spread dielectric grease, interesting that the ring terminals didn't look to badly corroded. Once I did this no more CEL and tach has been functioning.

The other thing I noticed is the last few months the voltmeter would stay just above the 12v mark. Since cleaning the ground wires the voltmeter consistently reads just under the 14v mark and wipers work a little faster, etc. I'm pretty confident that the problem is solved but time will tell. In a month I'll update, thanks for all your help suggestions!