JeffRX7

I just finished swapping a s5 tII into my s4 tII and got it up and running. once i went to check the timing, i realized i had no spark on the trailing coils, and the tach was dead. i checked with a timing light and just resting a plug on the block and cranking it over. I tried swapping the trailing coil from my N/A in, still no spark. swapped the CAS from my old motor, still nothing. I'm kinda stuck. ive been studying the schematics and from what i can tell the only other part inline is the ECU! which im really hoping isn't bad... oh, also the coils all have power and the plugs and wires are nearly new. any help would be much appreciated!!! thanks

RockLobster

iTrader: (7)

You running the S5 ECU? What about the idiot cluster is that S5?

In limp mode the ECU on S5s shuts off the trailing coils and thus the tach dosn't work.

Two common causes for this are:

-Bad/lack of engine ground either main or smaller passengerside firewall ground.

-Bad trailing coil pack/ignotor

JeffRX7

I'm still running the S4 ECU and guages, the only thing S5 is the block, LIM and UIM and turbo setup. i used the S4 throttle body so the TPS would match up and removed all emissions, air pump, A/C and power steering(manual rack). If anyone needs info on the s4-s5 conversion, i might be of help!

I'll slap a better ground on the engine to chassis, see if that works. any more suggestions? could it be the ecu?

tIIsleeper

Your trailing plugs are fouled. Turst me. You still have another problem though. My s4 does the same except my tach works. I checked the plugs. Both fouled. I replaced them and they fould again after 5 miles. It runs too rich.

JeffRX7

as far as im aware, the tach will only work if the trailing coils are firing... i don't think they are just fouled, because i rested a brand new NGK on the block, and no spark...

tIIsleeper

If you have a lawnmower, pull off the plug boot from the plug on the lawnmower. Take a leading and trailing plug out of your car. Stick the plug from your car in there and see if it sparks when you try and start the mower. Do the same with the other plug. No spark=fouled. Spark=Fine.
You have to ground the plug as well.

buttsjim

I know you said your coils have power, but it sounds like your electrical connectors to the trailing coil pack may by dirty or have a disconnect. That would affect both the coil and the tach.

JeffRX7

well, shouldn't it have the same effect if i take a brand new plug, rest it on the block(ground) and crank the motor and have someone watch for spark? tried that. no spark.

JeffRX7

the connector plugs are fine and clean. I tried swapping coils last night and checked that, and metered all the wires... has power at the 2 pin, not sure what the ones in the 4 pin are supposed to read? anyone know or know how to test them?

tIIsleeper

With the car running pull the trailing plug wire off of the coil to see if the coil is sparking. You wont get shocked. Done it plenty o times before. Wear gloves to be sure. If there is spark then your problem is the wires or plugs.

buttsjim

I was looking at the online FSM, and the test for the 4-pin appears to require a special meter.

You can probably check the input voltages though. On the 4-pin connector, the yellow/blue wire goes to the tach, and the blue/red, brown/yellow, and blue/yellow wires come directly from the 1M, 1U, and 1X pins, respectively, on the ECU. If you check the chart on page 4A 30 and 31 of the on-line FSM, you can see what your voltages should be.

It looks to me like you should be able to either check the voltages at the ECU or at the harness side of the connector. But, I'm a certified electrical retard, so you may want to get someone elses's opinion if you're not sure yourself.

JeffRX7

wow, just checked with mazda parts, a new trailing coil pack is $1000!!! I'm not sure what else to try though... just swapped the ecu with my N/A just to see, and still no spark. guess i try to find a used coil if no one else has some insight on this?

misterstyx69

iTrader: (142)

never did a swap but have question...did you use the wiring harness from the s4 and hook it into the s5 and then use the s4 ecu?if so IMO could be the gremlin right there ..just a thought ..two cents or broke and busted!

JeffRX7

I did use the s4 ecu and harness on the s5, but the only things plugged in to it are the injectors, TPS, CAS, and temp/press sensors... and those are all from the s/4. It should think its still an s4 as far as i can tell.

misterstyx69

iTrader: (142)

I have been going through this forum for about 3 weeks solid,about 4 hours a night "cause i put a down payment on my very first RX7 and wanted to know every thing about it,so if i ran into a problem i would have a fair idea of what it was and be able to fix it myself instead of spending the big bucks to get it fixed...I am pretty sure i read somewhere along the way about the harnesses and that you had to use the whole set up...example..s4 out and s5 in ...use the s5 engine ,the s5 harness and the s5 ecu.It would only seem logical since that is what it was operating with before and it ran fine ,you would have no problem with one whole system out and another whole system in..just think of it as trying to replace a half a dozen apples with a half a dozen oranges and putting the oranges into the apple box.outside it's the same ..inside it's different.you know what i'm trying to say ..opinion of a newbie

ilike2eatricers

Have you checked your EGI fuse? How about the main relay?

misterstyx69

iTrader: (142)

like it says..jeffrx7 get more input on your situation ....if it was egi fuse the damn thing wouldn't start! take the light bulb out of the socket..eff all happens when you turn the switch on right? right...bud if you can get where i am comin from...check the forum...laid it out...swaps will have problems people have done swaps ..people get input on problem find out what it was and HOLY **** ..it's alive..(not tryin to be an a-hole)..stop..grab a cup of coffee ...smoke if you got em..sit back and search second gen topics..keyword swaps..i'll feel bad if I am wrong but please let me know anyways.got a coffee ridin on this one!still say it's the harness(stubborn i guess!!!!!!!!!)misterstyx69

HAILERS

There's just a hint of doubt in my mind. The engine is a series five. Right? Right. And ALL the harness are series four with a series four ECU.

If the above is true, then ohm out the wires from the Trail Coil to the ECU. If they are all ohming out, then start the car and read the input/output described in the section called Control Unit in the FUEL SECTION.

The only time I've had tach/trail coil problem is just after I had to jumper a car after I'd let the battery go dead overnight. After driving for sometime and then shutting the car off and restarting it would the tach now work. I've no real explanation for that happening. I've seen it twice in the past.

Put in the Trai Coil assy from your other car and try that.

JeffRX7

I guarantee it's not the fuse or the relay, neither the leading or trailing coil would get power. they both have a steady 12v on all the wires they are supposed to when the ignition is on. and misterstyx.... I see where you're coming from with that but i dont agree. every thing the harness is hooked to it was hooked to on the s4 engine. the coil is off the body harness anyway, not the engine harness. as long as the CAS is making a signal, it is wired straight to the ecu, then the ecu sends a signal back out to the coils. the CAS is the same s4 to s5 and the ecu is still s4. to put in an s5 ecu and harness you have to replace all the harnesses, cluster etc... as far as i can see the trailing coil has everything it should need to fire. the only thing i have left is to make sure its getting a trigger signal from the ecu, which i havn't been able to figure out how to test yet... there's a $40 coil pack on e-bay...might just get it and try it....unless someone else has a suggestion?? (hint hint)

p.s. I'm not sure what worked and didn't work on this car originally... i bought it with the engine half stripped out of it because it "ran poorly" maybe linked to this same problem??

JeffRX7

hailers, i did try swapping in the coil pack from my n/a, still no spark or tach... i read that its possible to damage the ignitor plugging it in with the ign on... which might have happened? or that coil could be bad too? it seems weird they'd both be bad, but i don't know of what else to try... still have to check the signal wires into the coil...havn't been able to get the pdf of the FSM up on my comp for some reason.

buttsjim

Here are some screen shots of the on-line FSM that may help. In addition to checking at the ECU, I think you can check the 1M, 1U, and 1X voltages at the 4-pin connector. I stated the appropriate wire colors in an earlier post on this thread.

I edited this post because I just noticed that 1M is an ECU input, whereas 1U and 1X are both outputs.

Hope this helps. If not, I'm sure Hailers will.

SirCygnus

iTrader: (1)

ey hows about this, check the airflow meter. unplug it via the metal clip, and try it again. i have having the exact same problem. no spark, no rpm gauge responce, and everyone kept telling me it was the coils or the relay. it was nothing. it was a junk airflow meter. go try it. it doesnt hurt to try it out. it took me one month of reaserching to figure this damn thing out.

JeffRX7

thanks sircygnus and ****, I can't wont have a chance to try anything on it till tomorrow morning, so ill test the ecu outputs as well as check the AFM....ive got a few of those around now... thanks again! any more suggestions appreciated as always!

SirCygnus

iTrader: (1)

well howd it go?

HAILERS

FYI, a coil assy that isn't bolted to the chassis won't fire. The body of the coil assy is the ground. This was just FYI. If it is bolted down then don't add grounds etc. Just make sure it's bolted down.

I guess your other car does not run?? IF it does put yours in that car and see what happens.

http://www.teamfc3s.org/info/articles/demystifying.html

The engine runs so I don't see how it could be the afm. If the afm was bad and drowning out the refv then I could see how the afm would keep the lead and trail from firing, but like he said, the engine runs and the leads work.