CBR 600rr 03 unbalanced cylinders and misfires

[rkliddiard]

Hi everyone,

This is my first post so hello, I hope this makes sense.

I'm with Aston University (UK) and we are using a Honda CBR600rr (03) engine but I'm having a bit of a problem with the engine misfiring and not settling. We've only run it a couple of times so far.

Initially it seemed like cylinders 2&3 were not doing anything as the exhaust temperatures did not increase at all. We checked spark plugs but all worked fine but there was some fouling on the plugs and they were wet with fuel. I brought the pulse width forward and now all cylinders are working but... cylinder 4&2 are about average exhaust temperatures of 379 & 363. But cylinder 3 is mega hot at 479 and cylinder one is 131. (degrees C)

There's a lot more information but I hope that enough to work on. At the moment we are working on the fuel injection start. At the moment the map seems to be backwards. The fuel starts injecting at 360 degrees after TDC firing and then increases for RPM and TPS... But we are going to change that and see what happens.

Cheers!

Rachel

[rkliddiard]

Hi everyone,

This is my first post so hello, I hope this makes sense.

I'm with Aston University (UK) and we are using a Honda CBR600rr (03) engine but I'm having a bit of a problem with the engine misfiring and not settling. We've only run it a couple of times so far.

Initially it seemed like cylinders 2&3 were not doing anything as the exhaust temperatures did not increase at all. We checked spark plugs but all worked fine but there was some fouling on the plugs and they were wet with fuel. I brought the pulse width forward and now all cylinders are working but... cylinder 4&2 are about average exhaust temperatures of 379 & 363. But cylinder 3 is mega hot at 479 and cylinder one is 131. (degrees C)

There's a lot more information but I hope that enough to work on. At the moment we are working on the fuel injection start. At the moment the map seems to be backwards. The fuel starts injecting at 360 degrees after TDC firing and then increases for RPM and TPS... But we are going to change that and see what happens.

Cheers!

Rachel

[Jon Burford]

Hi Rachel
Interesting, your running the cbr this year? Still using the CVT?

Just wondering what engine management your using?
I don't know the '03 too well but I assume it has a cam sensor? are you running it sequential injection?

[rkliddiard]

Hi jon,

Ah yes the famed CVT. No we are going for the built in gears in the engine. No more CVT.

We are using OBR euro 4 as we have a lot of historical use with the company. We have a CAM sensor that works and we are running sequential injection and to further my description above its actually cylinder 4 that is not firing. Not cylinder 1.

Cylinder temperature, #1 -290, #2 -510, #3 - 360, #4 - 20.

Thanks for the reply.

[Jon Burford]

ah that's a shame, we are giving the CVT a go this year. I guess we will be the only ones at Silverstone with it then!

Okay, sadly I don't have much experience with that ECU but I assume you can set the injection offsets on the sequential injection?
if it's down at 20 then obviously it's not even occasionally firing, which is strange with a wet plug and spark. it would suggest that the injection offset is very wrong, or a problem with the ignition timing.
was the engine running when you bought it? just trying to find out if it's a problem with the physical engine or the setup/electronics.

does your ECU offer any kind of diagnostic display. Our DTA has a diagnostics panel that lets us check for crank/cam errors etc etc.

Sorry I'm not offering any concrete answers, experience tells me that little problems like this are caused by tiny little faults. Especially if the engine was running before.

A long shot, check your plugs. if the missing cylinder is really wet/dirty give them a clean.

[Rex Chan]

It sounds like you're trying to get the engine running for the first time? I've been lucky with startup maps, but some teams just can't them started. So the first option is that the startup tune/section of the map needs changes.

However, assuming it's close enough get it running, the main thing I would check for is that all the injectors are firing when you think they are. Have you done a test/diagnostic on all 4 injectors? We use MoTeC, and they are wired so that injector outputs fire 1-2-3-4, regardless of the firing order you have set in the software. Thus, for a 600RR firing order of 1-2-4-3, we wire the #3 inj output to cylinder 4, and #4 inj output to cylinder 3. Not sure if your ECU has something like this?

Of course, check your ign outputs are doing what you think they are.

Based on the issue being with cylinder 3/4, hopefully you're problem is like what we had: just swap the actual inj connectors around on the fuel rail and it will solve the issue.

In the MoTeC m400, you can specify injection timing as start or end, and we use end of injection to be 200-300 degrees BTDC of the intake stroke. This shouldn't have a major effect on getting it started.

BTW: 360 deg after TDC of firing is TDC of the intake stroke. At diel, the pulse width isn't long compared to RPM/cycle time, so the angle has less effect.

[Jon Burford]

Thinking about what Rex said.
This problem did occur to us last year, we were running fine on the dyno, but when we started the car for the first time, it was missing. It transpired to be this problem, but on the ignition side of things rather than injection.

Hope that helps a little more

[Luniz]

Just out of curiosity, have you been using the OBR Euro4 before? If not, make sure that the firmware version and the release version of the descriptor file on you laptop match. Otherwise the data you write to the eprom on the ecu ends up in just some random place and you don't really know what the ecu is doing.
We had that problem with this exact ecu last year and it took us some time to find the reason behind it.

[rkliddiard]

Hi All,

We got it in the end. Jon you were right it was the spark plugs. Most of them were on their way out and then died. We bought new ones (not cheap for stock CBR600rr, the lady at the till had to double take at the price) and voilà, all working now.

Thanks for all your ideas and help.

[rkliddiard]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Luniz:
Just out of curiosity, have you been using the OBR Euro4 before? If not, make sure that the firmware version and the release version of the descriptor file on you laptop match. Otherwise the data you write to the eprom on the ecu ends up in just some random place and you don't really know what the ecu is doing.
We had that problem with this exact ecu last year and it took us some time to find the reason behind it. </div></BLOCKQUOTE>

We've also had problems in previous years with firm ware but lucky we'd learnt from that mistake and that was one of the first things we checked but thanks for the advice.

[Rex Chan]

Rachel: see if you can get a spark plug sponsor - the stock CBR600RR plugs are NGK, but Denso also make one, and we had them sponsor us 4 boxes (16) a few years ago. We also take our engines back to Honda MPE (in Aus), and they seem to put new ones in for us too.

[Jon Burford]

Goood.
Glad you got it sorted and yes bike plugs are expensive!

Good luck with the car build. Hope to see you at Silverstone.