emerald crank sensor problem
Discussion
My first race of the year in the drag polo flagged up a problem with the crank sensor.
I wondered if anyone has had the same problem.
The car starts and runs fine till I reach 5.5-6k rpm and then the led on the top of the ecu momentarily goes from green to red and the rpms on the live mapping page drop to zero for a split second.
This acted like a rev limiter and my car would not rev past this point.
I wondered if anyone has had the same problem.
The car starts and runs fine till I reach 5.5-6k rpm and then the led on the top of the ecu momentarily goes from green to red and the rpms on the live mapping page drop to zero for a split second.
This acted like a rev limiter and my car would not rev past this point.
Well you didn't say that!
The issue is present because at high RPM the crank sensor signal is degrading to a point where the ECU looses 'sync' (I say 'sync' in inverted commas as GEMS/Emerald don't run sync in the same was as per Pectel, Life, Tag etc.). The red light and 0RPM is present whilst the ECU reacquires an accurate engine position. Until it has it is impossible for it to run the engine and all fuel and spark events will shut down.
My first comment of check its wired correctly was because in 95% of cases a new engine electronics package showing a similar issue will be due to the crank sensor being wired back to front.
In your case check your earths and the condition of the shielding on the CPS loom (if not twisted pair) and replace the sensor if this does not solve it. It'd also be worth scoping the CPS sensor, or at least logging at a decent rate the raw CPS signal if the Emerald supports this, so you can see what is happening to the signal at high RPM.
The issue is present because at high RPM the crank sensor signal is degrading to a point where the ECU looses 'sync' (I say 'sync' in inverted commas as GEMS/Emerald don't run sync in the same was as per Pectel, Life, Tag etc.). The red light and 0RPM is present whilst the ECU reacquires an accurate engine position. Until it has it is impossible for it to run the engine and all fuel and spark events will shut down.
My first comment of check its wired correctly was because in 95% of cases a new engine electronics package showing a similar issue will be due to the crank sensor being wired back to front.
In your case check your earths and the condition of the shielding on the CPS loom (if not twisted pair) and replace the sensor if this does not solve it. It'd also be worth scoping the CPS sensor, or at least logging at a decent rate the raw CPS signal if the Emerald supports this, so you can see what is happening to the signal at high RPM.
Edited by Icarus_ on Tuesday 14th April 14:13
marT350T said:
the led on the top of the ecu momentarily goes from green to red
What does that signify?marT350T said:
the rpms on the live mapping page drop to zero for a split second.
That might suggest loss of crank signal. Can you tell whether an ECU reset occured? Do you just have the single crank sensor? For example sequential systems would have a cam sensor too.
How is the crank sensor wired up? It would usually be via a dedicated screened cable with the screen earthed at the ECU end. Even so it's possible for it to pick up pulses from adjacent leads especially HT leads, so check that it's routed as far away from other leads as possible and where it has to pass them don't allow them to run parallel.
GreenV8S said:
marT350T said:
the led on the top of the ecu momentarily goes from green to red
What does that signify?marT350T said:
the rpms on the live mapping page drop to zero for a split second.
That might suggest loss of crank signal. Can you tell whether an ECU reset occured? Do you just have the single crank sensor? For example sequential systems would have a cam sensor too.
How is the crank sensor wired up? It would usually be via a dedicated screened cable with the screen earthed at the ECU end. Even so it's possible for it to pick up pulses from adjacent leads especially HT leads, so check that it's routed as far away from other leads as possible and where it has to pass them don't allow them to run parallel.
have just red the instructions and have seen how it should be wired with the screen earthed at the ecu so I will check that.
I have just installed a laucnch control and flat shift system , and they splice into the wires running to the coil packs. These wires run abot 5 cm from each other so do you think this could be causing interference even if the sensor calble is screened ?
MarT350T
im using the emeralds own flatshift system (std on K3). By setting the throttle %age to about 15%-20% im hoping to us it as a launch system too (clutch depressed throttle wide open, ign retarded against the flatshift limiter, hopefully should see some boost on the gauge with no load). Havent tested it in real anger yet, will do on the 25th of this month, let you know how it goes.
i assume you have spliced an aftermarket system in?
im using the emeralds own flatshift system (std on K3). By setting the throttle %age to about 15%-20% im hoping to us it as a launch system too (clutch depressed throttle wide open, ign retarded against the flatshift limiter, hopefully should see some boost on the gauge with no load). Havent tested it in real anger yet, will do on the 25th of this month, let you know how it goes.
i assume you have spliced an aftermarket system in?
Edited by CNHSS1 on Tuesday 14th April 16:03
marT350T said:
I have just installed a laucnch control and flat shift system , and they splice into the wires running to the coil packs. These wires run abot 5 cm from each other so do you think this could be causing interference even if the sensor calble is screened ?
The ignition system is the worst source of electrical noise, so LT or HT cables running close to the signal cable are a bad idea in general terms. 5cm with a screened cable doesn't sound likely to be a problem but if you can see any way to move them further apart you could see whether it makes any difference. Wires crossing at a sharp angle are generally better that wires that run parallel.marT350T said:
I dont think that putting a scope on will tell me anything I dont already know. I know the signal is being lost from the led and from the live mapping screen when the rpms suddenly go to 0 for a split second.
the signal may still be there...just too weak for the Emerald to see it.or it may be getting lost completely. A scope will tell you this.
Ideally a scope tagged onto the wires directly at the ecu, so it runs through the wiring also.
Easiest option is to try a new sensor though.
stevieturbo said:
marT350T said:
I dont think that putting a scope on will tell me anything I dont already know. I know the signal is being lost from the led and from the live mapping screen when the rpms suddenly go to 0 for a split second.
the signal may still be there...just too weak for the Emerald to see it.or it may be getting lost completely. A scope will tell you this.
Ideally a scope tagged onto the wires directly at the ecu, so it runs through the wiring also.
Easiest option is to try a new sensor though.
At this point though as CPS are cheap I'd visual make sure everything looked good, isolate any new bits and try it then. If the problem still persists fit a new CPS, if it still persists get the scope out.
Presumably your sensor uses screened cable right back to the ECU with the screen also being the sensor ground ? If not and it earths via the block then check that there is still a good low impendence connection from the block to battery –ve and also directly from the ECU to the battery –ve. A good thick ground for the ECU is important because any filtering of the sensor input to remove noise will require a good ground to decouple to. If the ECU is seeing noise on the sensor signal don’t exclude the fact that it could be a fault in the ignition circuits that is generating noise that it didn’t do previously. Certainly hanging a scope on the ECU input would seem to be the starting point.
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