***UPDATE – Never put the word resolved with car issues until you are 100% sure! I never really resolved the issue, the 2jzgte vvti igniter seems to have limitations, I ended up going to a LS2 LQ9 Coil setup, info on the kit and installation can be found HERE
Everything posted below is what I did to minimise the issue but I did start having ignition issues again, I’ve amended the post below with all the updated information. I’m going to change from the stock 2JZGTE VVTi coils, leads and DH61 igniter to the LS2 LQ9 coils and report back my findings. I think there is fundamentally an issue with pushing higher boost and power with the stock DH61 igniter***
Have ignition issues? Never under-estimate the importance of the correct spark plug heat range!
For a while now I have had varying levels of spark blow out or ignition break down at anything over 23psi which I though were just bad coil packs, here are some of the things that were occurring, what I replaced and what I did to resolve it;
I originally had break up around 23psi on the dyno and less break up issues on road, came in around 5500rpm and was worse as the car got hot to the point where it was almost non-drivable. I ended up changing the igniter with a 2nd hand unit from Japan which seemed to fix the issue when the car got hot, but it still seemed to have a slight miss in the high rpm (6500rpm+) but way better than it was to the point it wasn’t an issue, this was probably more due to the cooler weather testing.
Got a retune before my last event (1000m sprint) and it seemed to pop it’s head up again as running a little more boost, so even though my coils and leads looked in great condition I brought brand new stock vvti coils and leads, plus some coil pack connectors, then ran an extra earth from head to body. Issue still occurred. It seemed to get worse with heat again. I found that 20psi setting had no issues at all and had no misfire all the way to 7200rpm 🙂
I ended up playing around with different spark plugs and gaps, smaller gaps helped but to a point where gap was too small and I was masking the problem, plus it was still misfiring.
While I was also troubleshooting I found issues with 1 of my injectors and had them serviced, flowed and cleaned which is still an issue after this. Also a 1 volt drop across a fused distribution box was found which I resolved.
What I replaced or purchased;
- Brand new genuine VVTi coils
- Brand new genuine leads
- Brand new geunine coilpack connector clips
- Okada Plasma booster (Used on ground side of coil to increase spark current) – Couldn’t get DLI
- New power distribution post to replace fused one that was dropping 1 volt from alternator to battery
- Created further earth/ground wires from engine to frame and frame to transmission
- Ran new ECU earth wires to engine block
- Ran igniter earth to engine head
- Tested a 12v+ wire from fused distribution to igniter B+ wire (Only do this for testing, car won’t shut off in an emergency)
What I checked and tested;
- Checked all coil wires, igniter wires and earths (All parts including old ones within resistance specs)
- Battery power seems fine (13v+) and checked logs on ECU to confirm
- Ran 2.4, 2.2 and 2.0 coil dwell settings @ 13-14 volts – gets worse with less dwell
- Ran BKR6E, BKR7E, BCPR7ES spark plugs at .8mm, .7mm and .6mm with the .6mm being the best gap
Resolution: (Which wasn’t the resolution in the end)
In the end it came down to spark plug heat range, I brought some BKR9EIX spark plugs which resolved the issue, I was previously running BKR7E copper plugs @ around .6mm gap, I wanted copper plugs but couldn’t find any copper ones in the 9 heat range in stock anywhere. The new plugs gap is left alone at .8mm gap, this gap in the past would cause all sorts of misfire! Ran 23psi for over 30 minutes the other day wthout issue in hot weather where the spark break down would occur more often than not.
Now I just need to resolve the rich cylinder condition related to my ID2000 injector and supra should be ready for another tune and more boost without spark issues 🙂
Ran an extra wire from the igniter earth to a common earth that is connected to the engine head, also moved my okada plasma booster earth to this also. Took for test drive and it did seem to improve the issue a little, miss was still occurring though, just not as bad as usual.
Next test I did was run a wire from my powered distribution post which runs to starter, fuse box and battery so it’s the closest I can run from the alternator. I ran the other end to the B+ 12v on the igniter wire. *It’s worth noting that this is also the circuit for other devices such as the injectors and I highly recommend not using this method as your car will not cut off in emergency, this is purely used for testing running the coils at close to alternator voltage!!!
This time there was no to very minimal break up! Obviously with a better burn the AFR’s weren’t as rich, boost was up another .4-.6 psi and the car pulled very hard @ 24psi all the way to redline (7400rpm).
Based on all of this information it’s quite obvious the coils aren’t getting the primary spark voltage they need at higher boost levels and a device will be required to boost primary voltage to the coils. The cheapest and most effective (out of the box) option is the Kenne Bell boost-a-spark (http://www.kennebell.net/KBWebsite/A…oostaspark.htm), it’s only around $230 + delivery and almost half the price of most other solutions such as HKS DLI, Okada projects lift, other CDI devices.
But after some thinking on the Kenne Bell Boost a spark setup I don’t think it would be very practical, I would need to isolate the coils +12v power supply as it’s shared with the fuel injectors (just like non-vvti) – not too hard but just more stuffing around. If I did just run it off the shared B+ from the igniter then yes it probably would resolve the issue with voltage and get what I set the boost a spark product to (Probably 14-15v) but then the injectors would also have 15v. This would mean the ECU is still seeing what ever the battery voltage is (usually 13v or so) and then there would be no way of setting dwell on the coils or deadtime on the injectors correctly as there would be a mis-match on the voltages on the 12v+ circuit.
I could get away with running an isolated coil 12v+ and dropping dwell on coils across the board to compensate for the extra voltage but this just further complicates the setup.
I think it’s finally time to ditch the 2JZGTE VVTi coils and igniter setup and go with the LS2 LQ9 coils, just too many variables with the stock setup running high boost and unknown specs on igniters and using shared power with no feedback of real voltages of coils and injectors to the ECU.
***Note for anyone reading this thread – I removed the wire after the testing for safety reasons, make sure if you do this then you also do the same***