Strange issue i have encountered

[fatlapit]

Some of you may know i blew 3rd at fcs. I have changed my box. Easy bit done. So i fire her up and shes horrible and not happy. Miss firing not idling being a general pita. So i think vacuum leak and wiring. Either aomething ive not connected or somethings not tight. Nope non of that. So then i started to pressure test all the componants engine side of the tb. Er no problems. So i put her back together again. Still being a b**ch. So i thought hmmm ill plug the laptop in. Nope everything fine there. ffs wat can it be. So i started speaking to my next door neighbour. He says youve not get anything sensetive close to the fly wheel??? No i dont think so. So any way put her away thought nothing of it. So the next day i wiggled some wires and boom fixed awesome i thought. Took her for a test drive. Everything fine on boost iff boost and cruise all spot on. So i thought get home n wash her. So she decided to play up. This time fine on boost horrible for everything else. I get home let her cool and open the bonnet. Instantly looked at the flywheel area. Crank plug sitting right where a plastic bung for the bell housing should be. So i un plugged it and re routed the wiring. Turn the key and shes spot on.


Who would of thought thats the fault?? Must of been scrambling the signal. Totally crazy.

[Dum-Dum]

It's why crank sensors run shielded wiring.

[Ruan]

I wouldn't say that common - could be a failing crank sensor - they're usually pretty immune to interference due to the fact the crank sensors on the 60-2 tooth flywheels are Hall effect sensors, which work off the magnitude of flux, rather than the rate of change as in a VR sensor and output a purely digital signal which is generated by some circuitry inside the sensor itself.

I've known of engines have a real problems with starters with worn brushes affecting the crank synchronisation signals due to their proximity and refuse to start with the starter, but fire instantly when bumped - so wouldn't put it past it. As long as the wiring runs nowhere near the coils/HT leads if you're using them, I'd probably say it's not.

First thing I'd be doing is confirming all the wiring back to the ECU, if not try and get an oscilloscope and watch the signal whilst cranking and running, it should be a perfect signal. The fact that when you're adjusting wiring it fixes it would instantly say to me dodgy connection rather than anything else, though...

[Niall]

Sounds to me like failing crank sensor. Add to your live data on MAP crank error and watch it. You may get a count of 1 or 2 whilst starting but it should never go up when the car is running. If it does, dying crank sensor or bad wiring.

[fatlapit]

I would like it not to be either tbh niall. Everything is new.

[Ruan]

As said, who made the loom?

New parts can easily fail... Wiring is one of those things that can be particularly difficult to get right, the wrong route can cause mega problems.

EDIT: Just read you've changed the box, I'd put money on a wiring problem or connection issue if it was running fine before.

[Niall]

I would like it not to be either tbh niall. Everything is new.

Just because its new doesn't mean it won't fail. Ive had parts fail out of the box. Like i say, get recording your crank error and go from there.

[fatlapit]

Ok chaps cheers for your advice

[Niall]

Thankfully the omex is a very simple bit of kit. If you do have a crank error (like i say, 1 or 2 whilst starting can be normal) appearing and creeping up, it will more than likely be a new crank sensor!

[fatlapit]

The crank sensor is very prone to interference being a hall effect sensor. They have a shielded twisted pair cable as standard. What cable has been used on your new loom? If it's not a shielded cable with seperate earth into the ECU for the crank sensor that will be the issue 

From rich w

[Ruan]

Hall effect sensors are the least prone to noise, but either way - too much interference will cause the issue no matter, but I'm surprised there's enough EMI to make it switch past the TTL level unless the cables are literally going past the coils...

[Niall]

Also if its a omex built loom (even if you just bought the loom kit where its literally just tails and the plug), it will be with proper shielded cable and correctly earthed.

[fatlapit]

The issue is the flywheel and the crank sensor wiring. All sorted now

[cully]

what was the issue with the flywheel?

[fatlapit]

The hall effect from the fly was interupting the signal to the ecu