Cam sensor troubleshooting

[ignitionautosport]

Kawa, hey? I got a ZZR600, but no benefit to run DTA on that, it's carbed. lolll Well ok for timing it may be good, but no fuel.

so convert to efi

/derail

[FrankCorrado]

hahahahah thought about it.

[lumley32]

ZZR600, raced them in sidecars back in the day, turned most of them into piles of scrap after using a Vance and Hines ecu that only limmeted the revs some of the time! lol

[FrankCorrado]

Ok so I fixed half of it. The car is very driveable, but I cannot got over 50-60% TPS and 3300-3800 rpm at the same time, which makes the whole thing useless. lolll

If interferences is the problem, then no matter where I place my wire and if I ground or not the shield doesn't change anything. Kev, my wire is not further away from the coil pack then yours was.

Basically most of the time when I am over 50-60TPS and around 3500rpm the engine misses 4 cam signals, sometimes 2, and a few get rejected. I got a couple rejected and 10 missed in my last 45mins drive. When it misses 2 signals my AFR goes from 11.5-12 to 16 and when it misses 4 signals at the same time it goes to 20. Generates a lot of pops. Under 175-200kpa.

Now if that is wire related, I wonder how a wire can fail past a certain rpm and tps. I went up to 4200 but under 50TPS and all was fine. Not sure wire is my problem, how can the wire be more affected if it's 80kpa or 180kpa? If it was wire, it would fail all the time, to me, or be very rpm or timing specific, no matter the load.

I use my OEM ignition wire from the OEM harness (Kev) connected to a non-OEM relay which switches on 12v+ from battery (connected to relay) to the cam sensor. That same relay using same power source and same ignition source feeds 12v to the injectors, which never never never had a wire problem. The ground is the same for both. That same ignition wire is split in 2 so it also feeds another relay to feed 12v to the coil packs. Which run perfect as well.

I had to do that cuz my old stand alone could not stand OEM wiring and was requiring the use of independent relays plugged directly to the battery (go figure, but I followed the instructions). So I re-used that for the DTA. I don't see why it would not work if installed properly. Voltmeter and resistance tests show no signs whatsoever of a bad installation.

Also my crank sensor, using same type 2-core wire as the cam sensor, never misses a tooth.

Next step is to check the clearance between trigger wheel and sensor. I think it's viable to think it's possible if the clearance is too wide it could miss triggers under load and higher rpms. But still, I just don't get that load variable in the equation...

What's really interesting here is that light load and high rpms no problems.
Light loads = higher timing = more use of the coil pack = more possible interferences. Result: no misses.
High loads = less timing = less use of coil pack = less possible interferences. Result: misses trigger.

I wonder the explanation of that pattern, I just don't understand what the load would do to come into play here.

I think someone has had a similar issue on the old forum, too bad it's gone now.

[VR6Turbo]

Any chance you could have cracked the cam sensor trigger? Quite a common thing as it's a plastic sensor that's quite fragile.

[FrankCorrado]

Good point! Since I have to remove the cam cover anyway to check the clearance I'll of course check in which shape the trigger wheel is.

[FrankCorrado]

Well I removed the cam cover to take a look. Would be better if I remove the side cover, but it's a much longer job, so I tried to see anyway. The trigger is well in place and not cracked. Judging by the distance the trigger's edge is from the top of the cam bolt/nut and then looking at how far the sensor goes inside the cam sprocket, I am surprised they don't touch each other, so they certainly are very very very close. But clearance was not an option for me, as if it was the problem, it would not function properly even at lower rpms.

Now if I decide to remove the trigger and wave it over the the sensor to check if I get a rise in voltage, that's useless. At the moment it works when the trigger waves thousands times per minute, so twice a second will obviously work.

I'll ask my mechanic, maybe he's seen such a problem.

[VR6Turbo]

You could try shimming the sensor out a little if it's too close? Should be 1mm air gap I believe.

[FrankCorrado]

Yes my second to last thing to do is to remove side cover, manually move the cams so that I can precisely measure the clearance and adjust it. I won't be able to do such a thing before next Spring.

My last thing to do is get everything off, find an OEM cam sensor harness that is not even shielded, plug it in the fusebox and down to the cam sensor. Probably biggest job my engine would ever have. Was easier to upgrade to turbo and fit my old SDS system than if I try to put back some OEM harness I have never had before. But who knows, maybe that's were the problem is.

[FrankCorrado]

Interesting! I decided to swap back to PIN22 and see what happens. Turns out I get the same issues as before I changed for PIN23, which is 100% misses as soon as it cranks. Plugging back to PIN23 and... all good, except past 3300-3800 under 50-60TPS.

This means with the exact same configuration, I get different results for PIN22 and PIN23. Remember that PIN22 was working all the time for months and just stopped completely from working now. I don't know if PIN22 and 23 use the same circuit though.