Hi, my first post here. I've been lurking for some time now, and the info here has taught me so much. However, despite having done plenty of searches here and on Google generally, I have a problem I'm having a bit of difficulty sorting.
I have a racing car powered by two K8 motors. I have yet to race it, (I've only recently bought it) but have stumbled upon an issue.
The car came with a spare ECU, but it had yet to be flashed. So I sent it away together with the two fitted ECU's so it could be brought up to the same spec. Whilst it was being flashed, the person doing the job suggested some fettling. The main suggestion was to restrict the rev limit in the 'neutral' maps to 9k (to begin with) so when I am on the start line with the clutch down ready to go, I can hold the throttle on the floor and hopefully get a consistent launch. Once the clutch was up, the full rev map would come into play.
However, I now can't get either engine to rev past 9k. I read up on the clutch switches, and sure enough, found that someone had effectively by-passed the switches in the wiring. So after much research here I have now have it wired so that pin 69 gets put down to earth when each engine is started, to simulate the clutch being pulled in. The switch on the clutch will follow. However, the engines still will not rev past 9k, even when in gear (which I assume the ECUs would also need in order to run on full power).
Or is there anything else that might be holding the revs at 9k? problems with gear position sensor perhaps (I haven't yet checked these, but can't see both sensors playing up) - unless they haven't been wired correctly either.
What I haven't (yet) got is any clocks, so I can't say if there are any faults recorded.
Its still being grounded and the ECU still sees the clutch being pulled in, as a temp fix I would run a switch so you can still start it and then flip the switch after its started to get the full rev range.
Just check the B/Y and B leads going into the ECU. When the engines are in gear, with the clutch disengaged, none of the leads should be grounded. If one is grounded, the ECU will assume no-load conditions and use the neutral map. Did the engines operate properly (that is, reach the rev limiter) before the ECU flash?
Thanks for the input.
The B/Y wire is the clutch switch, what is the B wire? The two black wires in the ECU pinout diagram I have is an ignition coil, or Tip-Over sensor?
Sorry, I meant the Bl (blue) wire, not B (black). Not sure about the pin number right now, but it looks like the only Bl wire going to the connector. It's the wire coming from the neutral switch which is integrated into the GPS, but is a separate switch. Have you checked that?
Apologies, in answer to your other questions.
I don't know for sure where the rev limit was before reflash, but I assume the problem has always been there, just not noticed. This due to the fact that when I first started fault finding post reflash, I discovered both clutch switches (or at least the wiring) 'hard wired'. I then disconnected the earth supply to the clutch switch pinouts, and it was still the same. I did another search, which suggested that the ECU needs to see a 'change of state' during starting or it will remain defaulted in neutral maps, so I wired relays in that supply an earth to the B/W wires just when the starter is activated for now.
However, the engines still refuse to rev. A suggestion by the fella that did the reflash to check the gear position sensors found another issue. There was no discernible voltage at the pink wires (0.04v). Someone had spliced into them, and added a resistor to earth, with the GP sensors still connected too! So I've put them all back to standard, and all tests fine (test voltages found on here!)
But still the buggers won't rev!!!! Grrrr!
I tried doing the relay trick on my bike and it didn't work and would run on the neutral map, got a code from it. the B/Y needs to be on a switch, the B wire is just a ground IIRC.
I'm more comfortable referring to pin numbers than colors because of the multiple uses. For example B/Y is the clutch switch (pin 69) but it's also the camshaft position sensor signal (pin 8). B (pin 31) is the tip-over signal and the #2 ignition coil (pin 47). There are a few where you can get away with just referencing the color but you have to be careful. R is +12V and always hot. R/Bl is fuse protected +12V but otherwise always hot. There are other colored +12V lines that are switched. B/W is the main ground (pins 5, 36, 66, 68, 71) and B/Br is the sensors ground (pin 35).
It seems to me that you need a functioning clutch switch instead of a bypass. Can't that be rigged up? It may not apply to you but many threads here have arisen from people eliminating the clutch switch, sometimes unknowingly. It causes problems because the K7-up ECM adjustment of the ISC is influenced by the switch position.
You seem to be aware that you're running blind without a cluster but you can do more. SDS can be bought for $150-$200 and will display (among lots of other things) the clutch switch, neutral switch, and gear position in real time. That should cut through a lot of the unknown elements that you currently seem to have.
Thanks all for the input.
I appreciate the pinout numbers too, as I have also read colours can vary sometimes too!
SDS might be a very good idea, especially as the guide price is similar to a S/H set of clocks...on the rare occasion they do appear for sale!. Any recommendations for purchase (ps - I am UK based).
There's a downloadable spreadsheet that lists the ECM pin numbers, wire colors, and pin functions better than the service manual.
JK750: I'm not familiar with high speed datalogging. Can you provide some info or a link? SDS logs each of its 30 odd variables roughly every .2 sec., so if something else can be turned on I can see where there could be problems, either with transmitting all the data or with data line conflicts.
High speed datalogging is an option when you flash your ECU ( either with EcuEditor or Woolich), it transmits data faster.Something like 20Hz if I remember correctly
And to answer to the original question,I'm using a momentary button for the clutch switch,I press the button instead of the clutch,bike starts,then release the button and the ECU never sees clutch input again. And the bike revs normally to 14k. If the clutch input pin is not grounded,ECU uses the "gear" maps and rev limiters.
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