[PSIG]

+1. Fouled plugs also. DSC should be set for Falling if the polarity is right. If those images are Falling, then polarity is reversed. The correct polarity and edge setting combination is required for Speeduino to see gaps properly and with correct tooth timing. Verify that first. Go from there.

[CamJam]

So i checked the sparkplug leads and spark plugs. All leads read 2.2kOhms, and all sparkplugs are resistor type and gapped correctly (all around 0.8-0.9mm)
So i have narrowed this down to when the car is cranking with compression
Current setup is the max9926 has a 10kOhm shunt resistor on VR1 signal. Secondary signal is disconnected at the board)

When i crank the car with no accessories and no spark plugs installed. Only thing hooked up is the coil and spark leads, i get a perfect waveform out of the scope and in TS.

When i add the spark plugs in and nothing else i get very different waveform from on the scope.
The battery was showing <9V on a datalog so i joined 2 together and was only getting 10V on a crank.
I then removed the 10kOhm shunt resistor and got no change in scope or toothlog.

The real question is, how is speeduino ever going to know when a real tooth is missed when cranking and the signal is getting the same signal for dips on compression?

What does the max9926 signal expect in on its input voltage? i seem to be getting just over 300mV peak to peak on my current signal.

[apollard]

With two good batteries and it still dipping to 10v, I would check all connections for voltage drop while cranking. First suspects are grounds. Several OEMs have had TSB/recalls for ecm problems caused by bad grounds. One that comes to mind is Ford and a bad ground strap between engine and chassis.

[Jason4AGZE]

CamJam,
Looks like we are fighting the same problem. I am still taking readings with a scope and trying to figure this out. On a 4agze DLI. On the cam wheel the little blip I am 99% sure it is from the curve on the back side of the wheel. When I was scoping mine. I turned it back and forth at the sensor and it will show on the scope.

Your results of removing a tooth is my biggest fear.
I was going to buy this distributor here
https://www.carparts.com/distributor/re ... repg314104. And cut 2 teeth off 180* apart. But if I can't get a clean signal from the one I have already then I don't see that working. As it seems you have found out.

I still need to remove the wires running to my CAS to try and isolate that circuit from interference. My alternator sits just below and the charging cable runs the same path as the CAS wires.

But all in all I don't see how we can get rid of the little blip.

The only other route is crank wheel. MRP has a nice setup. But at $200.

[LPG2CV]

So move the cas wiring away from the alternator wiring. Make an effort Bruv!

[stum]

As LPGCV has mentioned. check on your wiring and possible "Cross Contamination" from other sources. On my Toyota installation i only had to move some other wires a little bit away (50-100mm) and the scope trace cleaned up a huge amount. The wire's i ended up moving where not what I would have classed as possible noisy cables. It was more of a untangle and separation ( a 30 second job)
Just show's how sensitive the VR trigger picukups are.

regards StuM

[Jason4AGZE]

The only thing that was holding me back was doing all the testing first.

For my setup I have to remove the fuel rail and a few other intake bits to get to it. I was just hopping for a set up in stockish form. I do have my harness out of the intake now. I just have to split it apart and run the line around. I should be able to get to that today.

[CamJam]

So back at it again and this time i have:
- Bought a 4age bigport distributor similar to what i had (24/4), the only difference is now the single tooth wheel doesn't have the extra half moon setup, as the new one had 4 teeth, and i chopped the other 3 off.
- Ditched the VR sensor setup and bought some hall effect sensors. I have been through the forums and found people using the Allegro ATS667/ATS627 so thought i would give it a go.

Managed to get the ATS667 hall sensors all wired up and installed in the new distributor using one sensor for 24T and another for 1T . Managed to get the timing setup on the car, and also idling with fixed timing at 5-10deg.

The only issue i am seeing at the moment is the car idles well between 0-5deg advance, but anywhere above or below this, the car runs quite rough, almost like its missing. The only thing that would make things better was increasing the dwell time from 3ms to 7 or 8ms.

Is it possible i have the rotor phase out? - i have just been reading up on this and could be something to try.
Currently i have been installing the distributor as per the factory manual - pretty much the rotor is sitting on point 1 at TDC.
Watching some videos, seems like i need to advance this to 30deg (or somewhere before point 1)?

[PSIG]

Yes, rotor phasing should always be checked. It's easy with dual wheel, as you set rotor position relative to crank advance by turning the distributor body, and then set your Trigger Angle so it times correctly. If you haven't seen my post on rotor phasing basics, look here. Note the comments in there about "bonus twist" will not apply to dual wheel.

[CamJam]

Just an update on where this went as i hope this helps others with a 4age 16V with stock wiring and distributor.
- The Allegro sensor lasted about a week before i started getting sync loss. I tried 3 more of the same sensors, molded and mounted the same way and played with this for a few weeks. It did work eventually for about 2 days, then just syncloss. I have a feeling the distributor is getting quite hot as its next to the exhaust and overheating the sensors. Not quite reliable enough for me.
- I ended up going back to VR sensors and ordering a JDM VR conditioner from PnPDuino. This required using the original wiring, but making a little dual jumper for G- to go to both the VR+ signals. This option also took some more modifying of the distributor to the 1T sensor. The main issue was the 1T sensor needed to cross at the same time as the 24T for the missing signal to work for missing tooth setup. This setup eventually worked pretty well. I did get some sync loss around 5500rpm, but i have a feeling this was due to the 24T and 1T signal not being perfectly lined up.
- I ended up going away from the missing tooth setup, as the car i have is a project/weekend car and never has a full battery by the time i jump in it. The missing tooth setup seems to struggle to start with a low battery (<12.6V), so i ended up just putting it back to basic distributor with the JDM VR and this has proven to be very reliable for what i need.
- I would still like to find a good reliable dual wheel setup within the stock distributor that can run coil on plug in the future. Just need more time playing with other options at this stage.