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In addition to what Chris stated above, I believe you need to do a modification inside the VEMS ECU. At least from what Ive read online while searching for crank trigger info a while back. You will need to install a resistor on the board. See here http://www.vems.hu/wiki/index.php?pa...riggerHardWare I would also wait for Peeps advise. From what I know all the PnP kits he offers is for VR triggers.
So, you have also verified that your +5V reference voltage from the VEMS ECU to the Hall sensor is good, and the signal and ground wires have good continuity from the sensor to the correct pin on the VEMS ECU?
The front missing tooth trigger wheel is correctly set up? That takes some trial and error.
So, you have also verified that your +5V reference voltage from the VEMS ECU to the Hall sensor is good, and the signal and ground wires have good continuity from the sensor to the correct pin on the VEMS ECU?
The front missing tooth trigger wheel is correctly set up? That takes some trial and error.
Finally I'm getting a signal in VEMS! I spent all day yesterday going through all the wiring and testing the sensor. I finally found one error in the wiring. It turns out the pull-up resistor was tee'd from power to ground instead of power to the signal output wire. Ughh I'm such an idiot... Got that fixed today. Now it gives a signal to VEMS, and I can see it on 'record triggerlog'. There is one issue the trigger is having while cranking, however. I'll get into that later.
One thing to note on the 'record triggerlog'. There is only a trigger signal after the engine starts cranking. If the ignition is on, but no cranking, it will say "no trigger input". I've seen quite enough of that message now, thank you very much VEMS. I was at first miffed that it still didn't see a signal after verifying with my little O-scope multi-meter that there was a signal voltage on pin 27 before plugging it into the unit. But it sees the signal as soon as it cranks. Just something to keep in mind for anyone else that runs into this situation.
So the car still won't start, not surprisingly. I am a little confused about what "TDC after the trigger" means. Iirc, when cyl.1 is at TDC, the sensor is 9 teeth before the missing tooth gets to it. The way I am interpreting 'TDC after the trigger' in this case is the first trigger tooth should be 16, while 'TDC after the trigger' is 90 deg. Does that sound about right? I will dial in my timing with a timing light, but is this close?
Now about the issue with the trigger. I am seeing a trigger error that says: "less pr.trig" In the help menu for this it says, "less primary trigger detected than it should be." That in and of itself doesn't make much sense to me. But my best guess is it is saying the voltage is too low. After looking at the triggerlog, it is occurring intermittently. But the engine state flag is saying "cranking/running on", and there are RPMs on VEMS. Maybe the pull-up resistor is toast? Or the sensor? Bad continuity? I'll double check continuity to rule that out. The sensor is new, but after seeing that there are other sensors out there that don't require putting in a resistor, I'm not liking this thing much now. But if it works, it works for now.
One thing to note on the 'record triggerlog'. There is only a trigger signal after the engine starts cranking. If the ignition is on, but no cranking, it will say "no trigger input". I've seen quite enough of that message now, thank you very much VEMS. I was at first miffed that it still didn't see a signal after verifying with my little O-scope multi-meter that there was a signal voltage on pin 27 before plugging it into the unit. But it sees the signal as soon as it cranks. Just something to keep in mind for anyone else that runs into this situation.
A Hall sensor or VR sensor will NOT generate a signal unless the engine is turning, so the "no trigger input" is perfectly normal in that state. With the ignition on and nothing else, all you'll see on an oscilloscope is a flat line; with a Hall sensor this flat line will either be at 0V or at 5V depending on whether the sensor voltage is pulled up or down.
Have you checked the actual sensor output with an oscilloscope while cranking the engine? It might provide some clues about the VEMS trigger error message.
Here's a screenshot of an attempt to start the engine. As you can see, there are some "less pr.trig" errors. They do look like they have a recurring pattern, although you can't tell from just this screenshot. It occurred to me this morning that maybe the error is coming from the fact there is a missing tooth in the wheel, but maybe it's expecting it in the wrong place in time. That would tell me the trigger settings are wrong. Regardless of that, I'm going to hook up a timing light and crank it to see where the mark is. To be clear, the car will not start ion its current state. I confirmed I'm getting spark on plug 1. I just put in about a gallon of gas. Plug 1 was wet when I took it out. So I think it comes down to the timing now. The trigger settings still has me confused, but I will play around with it and see if I can at least get the timing set while cranking.
Here's a screenshot of an attempt to start the engine. As you can see, there are some "less pr.trig" errors. They do look like they have a recurring pattern, although you can't tell from just this screenshot. It occurred to me this morning that maybe the error is coming from the fact there is a missing tooth in the wheel, but maybe it's expecting it in the wrong place in time. That would tell me the trigger settings are wrong. Regardless of that, I'm going to hook up a timing light and crank it to see where the mark is. To be clear, the car will not start ion its current state. I confirmed I'm getting spark on plug 1. I just put in about a gallon of gas. Plug 1 was wet when I took it out. So I think it comes down to the timing now. The trigger settings still has me confused, but I will play around with it and see if I can at least get the timing set while cranking.
You have a front crank trigger setup with hall sensor I assume. How many teeth and missing teeth. No you set cylinder 1 to top dead center / TDC. then could how many teeth until your sensor will pass the the missing teeth. I was off on my initial teeth count but the engine started, just needed to change the next trigger tooth. https://vems.hu/vt/help/v3/v3_primar..._settings.html
36-1 wheel running a hall sensor. Forgive me for the stupid question, but in what direction do i count the teeth from the perspective of standing in front of the car?
I also just hooked up a timing light and cranked the engine. No spark on any plugs. Oddly enough however, when I had plug 1 out to check for a spark, there was spark. That was earlier today. This car baffles me around every corner. No pun intended.
36-1 wheel running a hall sensor. Forgive me for the stupid question, but in what direction do i count the teeth from the perspective of standing in front of the car?
I also just hooked up a timing light and cranked the engine. No spark on any plugs. Oddly enough however, when I had plug 1 out to check for a spark, there was spark. That was earlier today. This car baffles me around every corner. No pun intended.
set the engine to TDC, verify with flywheel mark and camshaft mark ( if you only verify cam, you might be 180 out ). The check your front trigger wheel and sensor position and see how many teeth until the missing tooth going clockwise. So if its alot of teeth, rotate trigger wheel until its a lower number of teeth. Heres my trigger settings with a 36-1 wheel with VR sensor. Help with trigger settings menu https://vems.hu/vt/help/v3/v3_primar..._settings.html
So that green line represents your sensor position, correct?
Also, does the first trigger tooth need to be that first tooth before the missing? If that's the case, then my wheel will need to be moved. VEMS isn't seeing the missing tooth where it is expecting it. l Before, I tried setting the first trigger tooth as 16 to virtually flip the wheel over. The car didn't start. So that would explain why.
So that green line represents your sensor position, correct?
Also, does the first trigger tooth need to be that first tooth before the missing? If that's the case, then my wheel will need to be moved. VEMS isn't seeing the missing tooth where it is expecting it. l Before, I tried setting the first trigger tooth as 16 to virtually flip the wheel over. The car didn't start. So that would explain why.
The green line is TDC. The sensor placement in the picture would be in between green and red. First trigger tooth or FTT is the first tooth that passes over the sensor. The each tooth after that in clockwise rotation is 10 degrees. In my case my sensor was very close to missing tooth, so 0 teeth, then a little over 3 teeth would be TDC which I dialed in to be 36.5 degrees. Once you get her started you can play around with this number live and see/hear how the engine runs. Check on post #411 by @944crazy who has a better explanation.
Ok so I re-clocked the trigger wheel so the missing tooth is now 6 teeth away, before the trigger. 'TDC after the trigger' is set at 60 degrees. The engine wants to start. It's catching, and even ran on 1 cylinder for about 5 seconds at one point. But it won't fire. Would anyone like to look at my config to see if there is anything that needs to be changed?
Ok so I re-clocked the trigger wheel so the missing tooth is now 6 teeth away, before the trigger. 'TDC after the trigger' is set at 60 degrees. The engine wants to start. It's catching, and even ran on 1 cylinder for about 5 seconds at one point. But it won't fire. Would anyone like to look at my config to see if there is anything that needs to be changed?
.zip the config and upload it here. Since the motor is trying to catch and start, all the problem now is trigger timing.
Just checked and everything looks fine. What kind of 36-1 trigger do you have? Clewett? I would double check with engine at TDC where the sensor/tooth is in respect to missing tooth and next trigger tooth. Looking at my settings, my TDC after trigger value does not fall in an acceptable range, I have 36.5 and VEMS recommends 60-127. Will need to rotate trigger wheel and re-do my timing.
If you are still having trouble with your trigger setup, I stumbled across this forum over the weekend. A lot of Audi guys with the good old 5-cylinder engine use VEMS because it originally had the same crank trigger setup as the 944. It seems a number of them also had trouble converting to the later factory Audi 60-2 setup, but eventually figured it out. Obviously the trigger tooth counts and numbers will be different, but some of the threads here explain the logic behind the VEMS trigger menu:
04-13-2020, 10:12 PM
