vems trigger problems on aan

[diesel des]

Ok I'm trying to setup vems on my aan. I now actually have two brand new vems ecus. Both have the same issue. Car is fine on motronic. So I swapped the red and purple wire on the crank home sensor as described on the net. The car starts fine. But between 2k and about 3.5 k rpm approx I get triggering errors. Eg the rev counter bounces about mad and I get big backfired etc. If I keep the revs up the car drives fine but between these revs its undrivable. it actually seems better with the wires as standard.

Now the funny bit. If I start the car then set secondary trigger to disabled, then disconnect the sensor the car runs fine with no trigger errors. But the car is a balls to start like this. Sometimes it does sometimes not. It always starts easy with the secondary sensor turned on.

My vems supplier is helping resolve this hence the second ecu. But anyone any thoughts. Firmware is 1.74 and I'm using vemstune. Now I use a 7a flywheel but have been told this isn't the issue as new vems is ok with that. and I have just changed the clutch this week so I don't Fancy pulling the gearbox again. The pin looks fine on the flywheel.

Cheers des.

[Jamo]

Post your vemconfig file up

BTW the 7A flywheel could be the issue, as A80avant found the pin on the flywheel wasn't wide enough to trigger correctly.

[diesel des]

Ok will do tommorow when I'm on my computer. I haven't actually looked at the config file is it just a text file. Jamo I really don't feel like swapping the flywheel 2 days after doing the clutch. I don't want to ever see the dam flywheel again LOL.

[A80Avant]

no, no need to swap your flywheel, but the problem is there as Marc explained to me and eventually solved the problem.

2 solutions:

1) try and grind some metal off the bracket that holds the trigger sensor so that it turns slightly to 'see' the pin on the flywheel better. (that didnt work for me + we took the sensor closer as well, and even damaged one before realising that we werent progressing that way. BUT marc says sometimes it works

2) take the starter off, manually turn the crank to see the pin on the flywheel. YOu will need to weld some more iron next to the pin,make it wider or make a proper block of it. Make sure the height is the same as the OEM one or the dual mass flywheel one, and flatten the surface. After that it should work. Thats what made my car fire up and drive after that. Mine as soon as it fired, it hit 1500rpm and then fluctuated between 1500 and 15000 rpm reading making the car practically undrivable.

hope it helps

[jade]

I ran a 7a flywheel no problems, The map supplied with my Vems started my car but would of destroyed the engine if I tried WOT was not even close I am a good mechanical fitter engineer but without Repo,s help I would not of got anywhere with my vem and would of destroyed my engine. Get professional help to start with as most have

[diesel des]

Ok the welding to the flywheel sounds like what to do. Should i use a piece of mild steel and weld with normal rods. Or do I need dissimilar cast rods. I'm ok with a mma arc welder. What size of steel should I use. Any pictures. Wish I had of asked this last week when it was appart.

[terrybullwon]

Welding on to a factory balanced fly wheel sounds like a really stupid idea.

[terrybullwon]

Welding on to a factory balanced fly wheel sounds like a really stupid idea.

Moving the sensors closer buy removing metal sounds alot better. If you really have to make the timming pin "bigger" maybe worth going to a machine shop and have one with a off set made so its closer to the sensors and then it can also be weight matched.

[diesel des]

A few grams won't make a difference on this. It's not a full race engine. The sensor already seemed less than 1mm away so I think welding is my best option. Would like a picture though. Cheers des.

[jade]

Are you sure thats your problem before welding more on your flywheel

[Jamo]

A few grams won't make a difference on this. It's not a full race engine. The sensor already seemed less than 1mm away so I think welding is my best option. Would like a picture though. Cheers des.

Agree welding a pin isn't going to affect the balance of a street car

[Jamo]

Ok will do tommorow when I'm on my computer. I haven't actually looked at the config file is it just a text file. Jamo I really don't feel like swapping the flywheel 2 days after doing the clutch. I don't want to ever see the dam flywheel again LOL.

Config is just a text, you could just post screenshots of the ignition settings

[A80Avant]

that is what i was told as well. I dont get any problems with vibration or anything else etc.

The pin itself may not be more than 1 gram if you weigh it. Ok on 7000rpm spining even that 1gram is much heavier i suppose. Ideally it should be taken off, weld and rebalanced to zero. But as i say, mine was done as is and the amount of welding material is so little that it doesnt seem to affect the balancing. I have been speaking to a lot of respectable mechanics and shops around the UK as well regarding balancing and personally im getting the idea that it is being overrated when it comes to street cars or minor changes. Not everyone is building a race car.

On top of that, as mentioned above, solution 1(sensor moving) did not have any effect on vems reading the damn pin any better. So we had to go with solution 2.

Use material that is strongly magnetic and test it with the sensor before hand. Make sure it sticks to it, Or use a magnet for that matter.

Marc was telling me that there are variants of 7A flywheels and not all will cause this problem, hence why some have a problem and others dont.

managed to find a couple of photos from the garage days.

here is the pin and shows how small it is:



here is the weld ( picture was taken while still in the process. it needed refinement anyway)

[diesel des]

Thanks for the picture! that helps a lot. does the car still run on motronic if needed with this mod. cheers des.

[A80Avant]

i suspect it should run ok,but i havent tried it. My motronic has way different eproms in and i dont dare plug it in again.