Arghhh Cars !!!!!!

stevieturbo · Post by **stevieturbo** » Thu Jul 31, 2014 12:19 pm

When you say you got no crank sensor at all, exactly what do you mean ?

You are getting no signal at all, or the ecu isnt registering any response ? The two are not the same.

You cannot randomly change between VR and Hall without telling the ecu of the change, as they create different signals.

You do not need the engine running to test either sensor.

You just need a working sensor, a means of reading the signal, and for the trigger wheel to rotate.

the videos should have explained that fairly well.

Spongo · Post by **Spongo** » Thu Jul 31, 2014 12:22 pm

Ok there was no input into the MS with the new VR sensor at all no cranking signal and I even tried it on the old ECU and there was no tacho output from it either, and as I said the old sensor is a 2 wire unit (my bad) therefore must be a VR sensor yes?

Videos helped a lot thanks

stevieturbo · Post by **stevieturbo** » Thu Jul 31, 2014 12:37 pm

Spongo wrote:Ok there was no input into the MS with the new VR sensor at all no cranking signal and I even tried it on the old ECU and there was no tacho output from it either, and as I said the old sensor is a 2 wire unit (my bad) therefore must be a VR sensor yes?

Videos helped a lot thanks

But again, how are you determining no input ?

Unless you test the actual sensors output, you cant say that. If you are relying on the MS, then you are also relying on the MS being configured properly to understand the sensor input. As said, it's two different things.

Measuring sensor output with a scope relies on no other factors. Relying on some sort of output from the ecu relies on many factors being correct.

A 2 wire sensor would almost always be a VR mag sensor. This will create it's own output voltage in the form of roughly a sinusoidal waveform. You cant reliably test that with a voltmeter.

If the MS offers you a scope trace then that would suffice. I'm sure there are videos on Youtube explaining that too.

Most sensors will give an output regardless of polarity. But polarity is important as far as the ecu understanding the output is concerned.

DaveEFI · Post by **DaveEFI** » Thu Jul 31, 2014 1:40 pm

Spongo wrote:OK running an MS2 set up and when I installed the new sensor from Trigger Wheels I got absolutely no crank sensor at all, I tried to reverse the polarity as well.

Put the old sensor back in and it worked, incidentally I made a boo boo with a previous post as the old sensor is a simple VR one and NOT a Hall sensor, I thought there were 3 wires but that was a red herring sorry

So if I have the engine running I can simply put a probe on the correct pin on the MS plug and see what I am getting ?

I have re-wired the existing sensor to move the cable away from the noisy stuff and at the same time disconnected it from the now defunct ECU ( so I now have a check engine light permanently on and a somewhat erratic gearbox ) and I am still getting sync loss with no reasons on the dashboard.

The sync loss appears to get less as the engine warms up as well, does that help?

Its just so darned annoying it must be something simple but not related to sharing the CPS. I am thinking its an earthing problem but where to start ?

Right - it's a VR sensor. As has been said, these produce a less 'solid' waveform than a hall effect, so the wiring needs to be in top notch spec, including a screen. Also, MS may need some tweaking as not all VR sensors are the same. Is it definitely configured for a VR sensor? There are two input circuits to an MS V3 PCB, on only one (the VR input) will work with a VR sensor. Either will work with a hall effect.

If you look at the underside of the PCB where the legend is printed, Tach Sel should be linked to VRin. VRout to Tsel.

To avoid removing the PCB from the case, this diagram of the board from the component side might help:-

If all that is correct, the pots may need adjusting. I'll cover that later if it's configured correctly, but still doesn't work.

Spongo · Post by **Spongo** » Fri Aug 01, 2014 5:13 pm

Thanks Dave, I am sure it is set upo for VR but will now book some time in the MAN CAVE to check it out, I am also trying to fit a new bathroom in between work etc

Spongo · Post by **Spongo** » Tue Aug 05, 2014 8:28 am

Ok here is an update, board is set up for a VR sensor so no probs there, whilst I was poking around the vehicle wiring I had something of what I hope is a eureka moment, the signal wire is going to both ECU's so that the gearbox gets all it needs from the original engine ECU and the MS gets what it needs to run the engine. What I found also was that I had also run the ground connection to both ECU's

So now the ground connection has been cut to the engine ECU and everything still works.

It now appears to run much better with virtually no misfire ( I did get one but that may be an ignition lead as they run very close to my headers).

I still need to get the new VR sensor working though as I would like to have seperate sensors for each ECU to eliminate as many of these potential issues as possible.

Spongo · Post by **Spongo** » Mon Aug 11, 2014 9:31 am

So after removing the erronious ground connection all was well, misfire stopped and it was running well, then after a trip to one of those fast food outlets with golden arches I was sat in the drive through queue and temperature went up a bit not much then whammo misfire all over the place on both petrol and LPG. Once I limped out of the queue temperature settled and mis fire stopped on petrol but the car would hardly run on LPG.

Since then once warm the car wont run properly on LPG but on petrol its fine. gas pressure is good, coolant level OK, injectors are working OK as well.

Losing the plot on this one very fast.

unstable load · Post by **unstable load** » Tue Aug 12, 2014 6:15 am

At least you have narrowed your search down to the LPG circuit and systems.

Spongo · Post by **Spongo** » Tue Aug 12, 2014 8:28 am

True, I will try and get a log done as well that may help in the diagnosis.

Spongo · Post by **Spongo** » Mon Sep 01, 2014 2:05 pm

The plot thickens, I have found leaks on the inlet manifold that is letting a small amount of coolant into the engine and giving me the misfire so its off with the manifold and some new gaskets again