derSchwamm

iTrader: (1)

I can't find a good picture or diagram showing where grounds are supposed to be on a GSL-SE but I think mine are wrong or incomplete. Right now, I have the following grounds in the engine bay:

1. Negative battery to starter/bellhousing bolt
2. Small ground on top of engine, under vacuum rack from the engine wiring harness
3. Small ground from driver's side wiring harness to lower driver's strut tower
4. Ground wire run between the alternator and the driver's strut mount

And that's it. Is there supposed to be another negative cable run off the battery, like to the strut tower? Is the alternator ground run to the right place?

My fresh rebuild is very low on power and I think it's ignition related, so fixing the grounds might help (and testing ignitors, etc).

GSLSEforme

The original negative battery cable had a ground lug mid way in cable that bolted to lower inner driver side apron and cable continued on to starter.

Your alternator ground cable is an add on,not original.

What is battery voltage with car running. What is voltage at ignition coil primary terminals?

derSchwamm

iTrader: (1)

That explains a lot. I kept reading about a ground there but didn't know where it came from. My battery cable has nothing splitting off. Could I run a separate cable from the battery negative terminal to the body and get the same effect or should I track down an original cable?

Voltage is fine at the battery (I forget the exact value) but I will check the coils. Yesterday I swapped the two coils themselves and the car ran a little differently. It actually died randomly in the middle of driving, so I think I could have a faulty coil in the trailing spot now (leading previously) or maybe a bad trailing ignitor. Before I jump to conclusions I'm going to test all the j109s I have here and figure out which are still good. Rotating the ignitors also changed the way the car ran so I think at least one is not working well

GSLSEforme

Running a cable to body from negative battery terminal is fine.
Are the ignition coils Diamond coils?

derSchwamm

iTrader: (1)

They are both MSD blaster coils of unknown age and mileage

j9fd3s

iTrader: (3)

Might Stop Dead? Maybe Spark Died?

derSchwamm

iTrader: (1)

Haha. They came with the car. If you have a recommendation for a better coil let me know. Looks like OEM ones are long gone

GSLSEforme

Test them and see what condition they're in. Primary windings should be 1-3 ohms,secondary should be 5-6k ohms. If they test in spec,keep them and move on. Strongly suggest you do a spark test on ignition system.

Used Diamond coils can be found on ebay all the time,often replaced in search of more performance and can be picked up cheap.

derSchwamm

iTrader: (1)

Cool, thanks. Weather may limit my ability to test coils the next few days. Now that the FB moves the FD gets the garage back and the FB has to endure the weather!

All 4 of my j109s that I own tested OK using the service manual switch + 12v light bulb method.

Not or sure what you mean by “spark test” but with a timing light I almost can’t see the trailing plugs firing, or at least it’s too weak to make out the pulley mark. Leading works no problem. The trailing timing issue actually led me down the ignition path in the first place

GSLSEforme

Spark test-whole system. Have had J-109s pass test you just did yet not switch properly to let coil saturate and develop best spark.
Disable fuel pump,pull all plugs,put plugs back in respective wires and lay on top of intake.(Fully charged battery). Have a helper crank engine for 30 seconds or so,observe spark for quality and consistency. Spark color should be blue on all plugs and should be no dropouts. Switch out igniters to get best spark. Oscilloscope is best,results from doing above close second.

When you find best combo,use razorblade and clean mounting pad on distributor body and back of igniter and smear thermal paste on back of igniter. Helps insure long life for igniter.If igniter swap doesn't change spark quality,swap ig coils and see if problem follows part. If no change,ohm test pickup coils. I like to use a lab scope and look at signal/voltage generated. Check pickup air gap(use brass feeler gauges),too little air gap and not enough dwell time to fully saturate ignition coil. Specs are .023"-.035",have found .032" to be sweet spot for generating strongest signal/voltage/maximum dwell time for coils.

Blueprinting the pickups for maximum signal/voltage is the key to serious spark energy when combined with hi-amp GM ignition modules when doing a Direct fire conversion. You can see and hear difference in spark energy,color goes from blue to purple and sounds much like a mig welder.

Trailing ignition is only used to clean up emissions,has no effect on engine power.

j9fd3s

iTrader: (3)

that is a good tip!

GSLSEforme and i agree on several things,
1. GSL-SE good!
2. Tassel Loafers good!
and 3. the stock ignition works best when it is stock.

the blaster coils should work ok, you might switch them leading/trailing to see if the problem follows. you should check voltage at the coil too, if the battery is 13.6, if coil voltage is lower than about 13 (more than 0.5v drop) then you are loosing ignition power.

i also like a new cap and rotor, i like the OE Mazda/Mitsubishi parts. i always check the wires too, 16k OHMs is the limit, but a new one will be about 7.5, higher resistance in the wire, the less ignition power you have.
i would start with the stock spark plugs, and when it is dialed in the Rx8 Leading is a good option, it takes less power to fire, and it likes a leaner mixture.

derSchwamm

iTrader: (1)

Thanks everyone! Great tips here especially around finding the right ignitors to use. I just put a multimeter on my coils and got the following resistances:

Front/Trailing: 0.9 Ohm primary, 10,006 Ohm secondary
Rear/Leading: 0.9 Ohm primary, 4,380 Ohm secondary

Since GSLSEforMe said "Primary windings should be 1-3 ohms,secondary should be 5-6k ohms." and NONE of these numbers are in spec (and they're wildly different on secondary), I guess I should pick up two new or used Diamond coils next. I do have an FC coil sitting in the garage I could use for leading.

About trailing ignition only cleaning up emissions, I disagree... years back I had a leading ignitor die suddenly, which I swapped on the side of the road with the trailing. Getting home was a small struggle, especially with hills. Not having trailing spark sucked. ALTHOUGH this could be because the leading coil was also crap and my leading spark is weak too!!

j9fd3s

iTrader: (3)

yeah one of those coils is no good. if you can find a cheap pair of stock coils that is the best way

derSchwamm

iTrader: (1)

Until I started troubleshooting, the coil with 10k Ohm resistance was on my leading spark. I guess that could explain my lack of power?

GSLSEforme

Look on bay of e for used Diamond ig coils.All FB coils are interchangeable. MSD products...company is trading on a name,majority of their products are manufactured in china,blaster coils are one of those products.
Keep the FC coil for possible future DFI conversion-with a GM type ignition module. Attempting to use 2nd gen coil with J109 igniter will lead to igniter early demise-no sense ruining an otherwise good J109.

Regarding purpose of trailing ignition,you can disagree but its only purpose is to clean up emissions. I have driven an SE on trailing ignition only to get home,it ran but had NO power. Your recollection of swapping igniters doesn't seem logical as no trailing =no fuel pump and no rpm signal for SE ecu to use-car wouldn't run at all.Sounds more like no leading spark,fits scenario better.

GSLSEforme

Don't assume anything til you check everything. Cap,rotor,wires and plugs. Check condition of cap/rotor,test resistance of coil/plug wires. Good set of NGK wires only $15. What condition are plugs in,some engines just won't run right without a fresh set of plugs,if you're running same set of plugs you got your rebuilt engine started on...once you've figured out what other ignition shortcomings you have,throw a fresh set of plugs in it.

All 1st gen cars,on their best day-with brand new components have the weakest ignition systems of all 3 generations. They can't afford worn,near out of spec parts.

GSLSEforme

j9fd3s,i disagree on using RX8 plugs in stock 1st gen ignitions. I use the Nd racing version in my 2nd gen DFI ignition on my SE but would not recommend them for use in stock 1st gen ignition system. The coil can fire them but just,not enough power in system to fire them efficiently,more likely they will foul and work coils even harder in process. Best plug for oe1st gen ignition is NGK BUR8EQ14.

Comment about RX8 plug liking leaner mixture is due more to the coil that is firing it. RX8 system has more power than 1st gen ignition system.

t_g_farrell

iTrader: (1)

I used them with Ford E coils and GM ignitors and they worked great. I redid my ignition to get trailing going again and used an FC coil to drive both the leading plugs now. I can tell the RX8 plugs are not firing as well with that coil setup. I will go back to dedicated E coils for each leading plug on the next ignition go around.

derSchwamm

iTrader: (1)

You're right. I shouldn't have had fuel at all without trailing ignition. It must have been the other way around then

derSchwamm

iTrader: (1)

The car already has brand new plugs (BUR8EQ14) and new NGK plug wires. The plugs were installed shortly after an older set was used to get the engine started. I'll still check wire resistance to be safe. Cap and rotor are relatively new and lower mileage also but I'll see if there are ways to test them. Only the ignitors and coils are old and have been on the car as long as I've had it

j9fd3s

iTrader: (3)

if you can't control the mixture, then they don't work. my FC didn't like them at all.

derSchwamm

iTrader: (1)

Well, I may need to start a new thread since I'm pretty far off track, but what the heck.

I put a brand new NGK coil in the leading spot, and it runs about the same. I also swapped out ignitors. All 4 that I have test good. The car starts right up and seems to run ok but is still very low on power when I drive it. I pulled the leading plugs which were brand new and they were covered in soot. Running too rich I guess? They look wet in the picture but it's dry soot.

I noticed my bracket on the s5 throttle body means that the TPS is fully extended after only about a quarter throttle because the arm is longer. On a GSL-SE throttle body it seems to take about half throttle. I assume this can't help the problem but since near full throttle the TPS is fully extended either way I imagine this isn't the cause. Any other ideas?

Oh, and each rotor is making about 95-110psi compression about 40 miles after the rebuild as best I can tell with my harbor freight tester.



S5 throttle body with GSL-SE TPS

GSL-SE Throttle body and TPS position

GSLSEforme

Had you done a system spark test as previously recommended,results?

derSchwamm

iTrader: (1)

I have not. Honestly I am not sure how, since I wouldn't know what 'good' spark would look like and I also cannot see the color of the spark at all. I've relied on getting strong pulses from my timing light instead

derSchwamm

iTrader: (1)

Ok I tried the spark test this morning. Leading plugs are sparking when I hold them up to the firewall. Trailing plugs weren't because I disabled the injectors at the trailing coil negative lead. I'm not sure what else this test could tell me aside from that my plugs are working.

I also found two other issues which I fixed. First, the check valve under the ACV was missing so I installed it. I think this could have been allowing intake air to escape and throwing off the mixture, but aside from a slight lumpy idle it runs the same. I may need to adjust the TPS for idle again.

I also found that the diaphragm in the actuator on the front side of the throttle body is broken, so the actuator doesn't do anything. I think this is the actuator that closes the front pair of butterfly valves to enrich the mixture before the engine is hot? I rubber-banded it open for a test drive and it didn't seem to have an effect. It's the silver actuator in the top-left of my S5 throttle body picture two posts up.

I quickly checked the resistance between the ignitors and coils. 3.5 omhs trailing, 0.9 ohms leading. Not sure what the spec is but it's weird that they are different.

I'm open to suggestions on what to investigate next. Plugs are still covered in soot after a couple laps around the block