Hi, this is my first post, im new to VEMS, and the world of ECUS really.
I have just built a mk1 Clio Williams engine on Jenvey throttle bodies, catcams vernier, high comp pistons e.t.c
I bought the VEMS ecu and Prebuilt V3 harness off a very similar engine, and i used all the sensors from it.
On first startup it ran fine, couldnt be happier, no real problems to report, spent most to fhe day fiddling and driving it around a bit, i then parked up and tidied a bit of wiring and dissconected the battery, and car hasnt been able to start since...
Ive hooked the laptop upto megatune, and its obvious the problem is it cant detect a crank speed..... 0rpm.
However it will say, if you crank for 30 seconds, jumpt upto to something like 100-200rpm for a very split second before remaining at 0rpm, it might do it a few times in the space of a minute.
Ive changed the crank sensor, with no luck. Resistance accross both crank sensors is 220 ohms, resistance of wiring between crank sensor and the Econoseal 36 plug is 0.4 ohms. While cranking a 4v signal can also be found at the ECU plug.
So the crank sensor is fine....the wiring to the ECU plug is fine, then what the hell is wrong? ive not changed any Trigger settings e.t.c
One thing to note, if i dissconect the crank sensor and turn the engine over Megatune reads nothing, but if i connect and crank over, then it will still read 0 but "Trigger Error" will come up at the bottom in red.
Im running a Meganne flywheel with 60-2 trigger pattern, and this is a screenshot of the trigger pattern settings, unfortunately it means nothing to me and im wondering if any of you can shed any light onto something that is REALLY annoying me. Thanks.
Why would it work fine, and then not the next day, when nothing has been touched :S
(http://i133.photobucket.com/albums/q51/laine_16v/trigger.jpg)
Most likely you have fried P259 chip. Does fuel pump comes on when switching ignition on (assuming you have FP relay wired through P259)?
It's common that ECU doesn't register engine speed when this chip is fried because it ruins the 5volt supply to the LM1815 chip and it means no rpm reading.
This chip is cheap (4 euros or something like that) but you won't be able to change it by yourself.
Hi,
Fuel pump is manually wired, so cant use that to check.
Thats cracking, why on earth would it fry the chip, i didnt touch anything :( Is there a proper way of telling if this chip is 100% to blame or dead?
It fries already when ground wires are mounted to the wrong place or are not enough etc.
There is only 1 ground on my prebuilt wiring loom, and the earth was perfect as far as i can tell :S
like i ask, is there a proper way to diagnose it is that for sure? some sort of command i can run? *shrugs*. Also if it was completely dead, why does it register some RPM for a split second sometimes (albeit rarely)
Is there somewhere i can send the ECU away too to be repaired?
Wire up a neon indicator lamp to one of the P259 channels and energise this through Megatune by going to the RPM triggers under the extras menue. Select the P259 and then the chanel, set min and max parameters. if the light is not on, use the inverted chanel number (i0, i1, i2 and so on) if the lght still doesnt come on, the chip is a goner. Check all p259 channels in this way
Make sure you have 12v to the lamp first, then the ground for the lamp to the p259 channel, do not put 12v direct onto the p259 channel as that is a sure way of smoking the chip, if its not already.
OK to save me some time here,
Instead of using a lamp, can i just put a multimeter between the +12v and the P259 pin, and check for resistance, say to activate it when i push the throttle past 50%?
I dont have any lamps and cant be bothered to go any buy anything lol.
Hi,
You do need a small load on there, DMMs never give a 100% definate in this situation.
Cheers,
Gavin :)
Right, luckily enough.......
I have a friend who also has a mk1 clio running again a throttle bodied engine, on VEMS management. So i plan to go visit her, plug my VEMS straight into her loom and see if it detects a crank signal. :)
Ok just tried my ECU out on my friends car/wiring loom.
Its works perfect, picks up RPM signal fine! Back to the drawing board then :S
Hi,
Well that only leaves you with crank sensor, wiring or the trigger wheel has fell off!
With the VEMs unplugged check the resistance across the 2 crank sensor wires (at the 36pin plug) and each wires resistance to gound.
Cheers,
Gavin :)
Crank sensor is fine, like i say it measures 230ohms accross and gives 10v AC while cranking.
And my two other friends with same engien setup have identical readings too..
All earth pins on ECU plug read 0 ohms when earth is measured.
Trigger wheel is part of the flywheel, and last time i checked the flywheel hadnt fallen off lol! This is the MOST CONFUSING problem in the world and it just does not make sense AT ALL.
Anyone want to come and fix this for me? ill pay them handsomly!
Well, at least you have some good news in that the ECU is now a known good unit. When you say in your original post that you tidied the wiring and reconnected the battery, can you elaborate anymore? Was it literally just a matter of cable ties here and there, or was it more involved? Did you somehow swap the VR cables so the polarity is now wrong? May help us track it down.
If you give a location I'm sure there will be someone around. If you're near to me I'll gladly have a look. I'm in the Bedford area.
-Gavin
Quote from: Sprockets on March 15, 2009, 10:51:53 PM
Well, at least you have some good news in that the ECU is now a known good unit. When you say in your original post that you tidied the wiring and reconnected the battery, can you elaborate anymore? Was it literally just a matter of cable ties here and there, or was it more involved? Did you somehow swap the VR cables so the polarity is now wrong? May help us track it down.
If you give a location I'm sure there will be someone around. If you're near to me I'll gladly have a look. I'm in the Bedford area.
-Gavin
Yeah its good to know the ECU is ok. Yeah literally because the prebuilt V3 harness is so fricking big all i did was cable tie the excess plugs that i wasnt using toegher and then cable tied them to the main chunk of loom.
No havent swap VR cables over, not possible, its a Hall sensor anyway i believe, but not too sure (new to this and trying to learn as quick as possible :))
I live in Bristol, but will pay happily for someone / anyone who knows what they are doing with these ECU;s to come have a look.
Is the sensor 3 wire or two wire
3 wire is Hall and 2 wire is VR :)
Its a 2 wire sensor, swapping the wires is about the only thing i havent done. I havent done that because it ran in way it currently, but i will try it anyway tonight. If the wires were the wrong way around would you get the symptoms i am experiencing?
It has been known to be the cause of strangeness.
Does VEMSTune have a scope for the crank trigger similar to the likes of DTA? That would be a useful tool :)
Quote from: Sprocket on March 17, 2009, 04:51:46 PM
Does VEMSTune have a scope for the crank trigger similar to the likes of DTA? That would be a useful tool :)
I vote whole heartedly for this tool to be brought to Vems.
Completely rewired it all now, and get a consistent perfect crank signal now :)
Result, and some Karma points for getting that done sir.