Cam sensor signal missing

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
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vlad01
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Re: Cam sensor signal missing

Post by vlad01 »

The spark runs independent of the ECU, the DFI handles it. ECU is only controlling the timing other than the base 10º the DFI does itself.
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wrx884
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Re: Cam sensor signal missing

Post by wrx884 »

vlad01 wrote:The spark runs independent of the ECU, the DFI handles it. ECU is only controlling the timing other than the base 10º the DFI does itself.
Hmm so that kinda tells me it must be a wiring issue, i know i can easily do a continuity test but that doesn't always show if there's any corroded wires that could be causing a weak signal hey?
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Re: Cam sensor signal missing

Post by vlad01 »

Yeah, I'm thinking wiring too.


Just for good measure unplug the ECU and see if the spark is still missing. There is always a possibility the ECU might be shorting one of the signals/bypass to ground, not that I think that would stop the spark though but I guess you have to rule everything out.
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wrx884
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Re: Cam sensor signal missing

Post by wrx884 »

vlad01 wrote:Yeah, I'm thinking wiring too.


Just for good measure unplug the ECU and see if the spark is still missing. There is always a possibility the ECU might be shorting one of the signals/bypass to ground, not that I think that would stop the spark though but I guess you have to rule everything out.
Yeah right so technically if all is working fine i should still get spark if i disconnect the ECU? im at a point i'll try anything to eliminate any possibilities.
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Re: Cam sensor signal missing

Post by vlad01 »

Yes, it should still spark without an ECU. I had run a v6 on residual fuel in the manifold with no ECU connected. That's how I discovered they don't need the ECU for spark all those years ago.
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Re: Cam sensor signal missing

Post by kojab »

Shot in the dark.

No spark can be caused by very fouled or wet spark plugs. A WORKING timing light will not display spark when spark plugs are wet even in a car with no faults. This has caught out even good mechanics.

Pull your plugs and make sure they look good. If in doubt put a new set in and make sure you haven't got diesel in your fuel tank.
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Re: Cam sensor signal missing

Post by vlad01 »

I recall he mentioned that it wasn't sparking between the posts on the coil packs.
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wrx884
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Re: Cam sensor signal missing

Post by wrx884 »

Been a little while since i been able to jump back on this but had a crack today, i don't know if ive got any actual progress but i guess mayb something???

Now I've tried starting the car with no ECU to see if i get spark, i can say that with no ECU the car wont even crank so that's a no go test, but now I'm pretty sure i have all codes logged haha as i now have the engine light on always now after attempting this, so i don't recommend this unless u can get the codes clearly easily.

Took the harmonic balancer off again and inspected it and again i cant see anything out of ordinary.

Started checking for continuity through the entire wiring now i have better access to the crank sensor connector. Using the pics provided on page 3 i can say nothing is out of ordinary and i get continuity in each connector and pins from the crank sensor to the cam sensor, back to the DFI connector then back to the ECU and all those check out fine, even the grounds seem ok. The only wire that seems to go elsewhere else is the power in wire which comes from one of the 3 connectors on drivers side above the brake booster (green wire) then to fuse and all checks out ok. Now this doesn't mean i don't have a break or corroded somewhere still and could still be causing issues with the missing cam signal but thought id put the balancer back and test. The wires that i can see thats not taped up or inside conduit looks fine with no breaks on the outer wire case but sure enough, the car actually cranked over (not straight away) and ran, but was rough as and would stall out randomly but at least now i can get it running atm.

I decided to start checking my grounds as that's the next point in checking, now i thought i had a bit of a shitty wire connection on the black wire with red trace (might be orange trace?) that gets bolted to the ground point under and in front of the ABS module so i re did all these just for peace of mind. Sure enough it kinda started better and kinda ran a little better but i cant really confirm that the ground points were an issue or was just a coincidence? But one thing i have now noticed i can make the engine revs drop dramatically and even stall if i push up and down on the drivers side guard pretty abruptly and the issue pops up so this to me must sound like a wiring issue somewhere? Id do the same test on the passenger side i can create it but it takes much more effort so I'm thinkin my issue is on the drivers side? so I'm wondering if a full engine harness swap might be the go but if I'm to go do that can it be done easily enough while the engine is still in??
Last edited by wrx884 on Mon Mar 01, 2021 6:19 pm, edited 2 times in total.
wrx884
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Re: Cam sensor signal missing

Post by wrx884 »

kojab wrote:Shot in the dark.

No spark can be caused by very fouled or wet spark plugs. A WORKING timing light will not display spark when spark plugs are wet even in a car with no faults. This has caught out even good mechanics.

Pull your plugs and make sure they look good. If in doubt put a new set in and make sure you haven't got diesel in your fuel tank.
Yeah as stated man i checked for spark at the posts as its easier to check on my own that way. No chance of diesel being in the tank and the plugs are brand new since the motor swap


Ground point under ABS module. I did forget to mention i had upgraded the ground point here years ago and added a single 4 gauge wire from this point to the neg terminal on the battery to stop lights dimming with the stereo install.
20210301_135437.jpg
Heres some pics of the balancer if anyone else can spot something but to me seems normal?
20210228_165039.jpg
20210228_165022.jpg
'quipt4it
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Re: Cam sensor signal missing

Post by 'quipt4it »

I would do a 'wiggle test' on the 'Ground point under ABS module' in the pic., if you haven't already.
The crimping does not look sufficient from the photos.
Throw in a couple of star washers for good measure. I prefer crimp and solder.
I'm still leaning towards earthing/ connection.
Those vanes look mint btw
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