Something is a miss!!!

[Warnzie]

So....have a look at the attached video. My 6th gen has ran flawless and only had 11,000kms on the clock. I noticed the other day when cruising on a straight piece of road it was bogging down and then coming good? Kind of like a flat spot type of thing which is so strange cause I have a PC5 which has being custom tuned for perfect ratio’s and have never had a issue. I put it down to using 91ron fuel here in Australia where I usually use 95ron. Took it out today and got home and the thing as you can see from vid dropped it’s idle for no apparent reason? 
 

something is obviously a miss but don’t really know where to look. Would it be sensor related like tps or could it just be as simple as crap fuel?? Have checked my PC5 and no probs. Love to hear your thoughts

[Grum]

You could be right about a bad batch of fuel, I've seen a similar effect from crappy fuel. There's nothing wrong with running standard 91oct in a VFR, unless your PC5 has altered timing etc. Given your bike has only 11,000ks on the clock it should be running like new.

If you had a sensor issue you'd normally see a diagnostic error code flashing on the Fi Light.

Have you been using Ethanol blended fuel? Was your last fuel fill from a remote petrol station you hadn't used before? Any chance of condensation in the tank?

Definelty worth dumping what's in the tank and fill er up with known good quality fresh stuff, see how you go. Warm engine idle should be 1200rpm.

Also don't discount a dying battery, make sure your charging system is OK by checking the battery voltage with engine running, should see around 13.5 to 14.5volts.

Good Luck.

[Cogswell]

I'll apologize in advance . . . when I saw the thread title I had in mind it would be about something like this . . .  (more below)

 

 

Ok - now that my bad boy thing is out of the way,  the circumstances of your PC V are not particularly clear - you've been running it for some time, or, you just installed it and had it tuned on a dyno?  Are you using Autotune?   At any rate - do you have O2 eliminators installed?   Improper grade fuel will likely cause detonation or pinging if too low a rating, but the engine should still run fine as the energy content in the fuel remains the same.  If you have water in the fuel that will definitely cause problems.  If you suspect that, lift and support the tank and get absolutely every last drop out you can and refill with fresh and add some treatment to get the water in to suspension so it can be completely eliminated.   A sensor failure is certainly possible, but seemingly unlikely given the low usage it has on it - I would look for obvious things  as you've mentioned 1st, or things such as a pinched vacuum hose or the like. 

 

Let us know how it goes.

 

 

 

 

 

[Warnzie]

I wish I had that problem😂😂👍 a problem any of us would surely learn to live with😂👌🏾
 

I tested the battery under load with a 12v light bulb and we all ok in the battery department. Will fill tank with premium again as usual to see if it helps get rid of the issue, if not, think it might be best for me to look at vac lines to starter valves, and look at and sync starter valves to eliminate any possibilities. I’m regards to my PC5, I’m not running o2 sensors, have a cat delete and also a piper ross filter with stainies. Had it custom tuned 3mths ago and hasn’t missed a beat since then, if anything made a perfect bike that all the more perfect

[Cogswell]

You may want to visit Dynojet's website and look at the O2 elim specification for your PC V.  They're mandatory for a PC III and I believe also for a V.  The PC uses a set map and does not adjust based on O2 sensor input.  The ECU will change its output based on various parameters and the eliminators fool the ECU in to thinking that the O2 sensors are there and functioning as normal.  That keeps the ECU's output static so that the PC can adjust accordingly.  If the ECU does not have the elims and changes its output, the PC map no longer works as it should.  Check with Dynojet to be sure on a V.  You don't have to buy their elims - you can make your own using 1 each 330 ohm (1/2 watt or more) resistors in place of the O2 sensors - cheap and easy.  I'll scare up a photo of them installed on a 6th gen so you can see how they go in.  Even if that's not the problem it would be good to get that sorted if not already.

 

[Warnzie]

6 hours ago, Cogswell said:

You may want to visit Dynojet's website and look at the O2 elim specification for your PC V.  They're mandatory for a PC III and I believe also for a V.  The PC uses a set map and does not adjust based on O2 sensor input.  The ECU will change its output based on various parameters and the eliminators fool the ECU in to thinking that the O2 sensors are there and functioning as normal.  That keeps the ECU's output static so that the PC can adjust accordingly.  If the ECU does not have the elims and changes its output, the PC map no longer works as it should.  Check with Dynojet to be sure on a V.  You don't have to buy their elims - you can make your own using 1 each 330 ohm (1/2 watt or more) resistors in place of the O2 sensors - cheap and easy.  I'll scare up a photo of them installed on a 6th gen so you can see how they go in.  Even if that's not the problem it would be good to get that sorted if not already.

 

Sorry to clarify I am running o2 sensor eliminators😉👌🏾

[Warnzie]

So just a update, refilled tank from basically empty with the good stuff, have ridden 160kms with a few rides and bike ran flawless....but this morning it happened again!!!!! Blipped down to 3rd to go around a roundabout,

went to put gas on and it stumbled and flap spotted...got to top of hill where I sat at traffic lights as like as above vid the bike sat there idling at 500rpm. It does sound like it maybe running on a couple of cyclinder when it doing that? So, my next point of call is plugs and coils. Is there a easy way of checking the coils with a multimeter?

[Grum]

Be surprised if it's a spark plug issue they are Platinum/Iridium's good for 100,000k's. Dont know that an ohm meter will pick up an intermittent or faulty ignition coil, guess you may be able to do some comparison measurements. It would be worth removing them and individually checking there are no cracks or arc overs evident, or burnt looking connection to the spark plug.

How difficult is it to get your bike back to stock standard, bypassing all the PC5 stuff?

Wonder if you might have a fuel pressure issue, perhaps a faulty fuel pressure regulator?

[Dutchy]

Point an IR thermometer at the headers to see if one is way cooler?

 

The FPR is often taunted as an usual suspect on RC51 fora.  An easy check though: lift tank, pull the smaller (horizontal) tube, place a rag under, switch on ignition (donot start the engine). If fuel comes out, it is farked.

[Marooncobra]

Warnzie,

 

I had this issue plague me for a period. Sometimes it would run sweet and then out of nowhere start dropping revs when you come to a stop, having to keep blipping the throttle. Similar to your situation. I changed coil packs, plugs, completed a Stater sync, fuel filter but it would show up every so often. Just when you think you have solved it, after a couple of weeks of riding, it would come back 😩😩
 

I then did a complete clean of all electrical connections and also removed the earth block that is located in the wiring loom around the Throttle body by soldering in new joints to each individual wire and then wiring an additional earth back to the battery. I also did the same procedure and removed the earth block located in the nose cone and added a further earth wire all the way back to the battery. Since then she purrs and I haven’t had low revs plague me 😁😁
 

I put it down to a bad earth, cannot confirm which one as I cleaned them all and removed the earth blocks, and when you are riding it vibrates and produces a bad earth at certain times hence the low revs.
 

[Warnzie]

2 hours ago, Marooncobra said:

Warnzie,

 

I had this issue plague me for a period. Sometimes it would run sweet and then out of nowhere start dropping revs when you come to a stop, having to keep blipping the throttle. Similar to your situation. I changed coil packs, plugs, completed a Stater sync, fuel filter but it would show up every so often. Just when you think you have solved it, after a couple of weeks of riding, it would come back 😩😩
 

I then did a complete clean of all electrical connections and also removed the earth block that is located in the wiring loom around the Throttle body by soldering in new joints to each individual wire and then wiring an additional earth back to the battery. I also did the same procedure and removed the earth block located in the nose cone and added a further earth wire all the way back to the battery. Since then she purrs and I haven’t had low revs plague me 😁😁
 

I put it down to a bad earth, cannot confirm which one as I cleaned them all and removed the earth blocks, and when you are riding it vibrates and produces a bad earth at certain times hence the low revs.
 

Wow, thanks for the heads marooncobra😉👍 did yours suffer from the low idle and also surging / bog down feel when getting on throttle at low rpm?

[Marooncobra]

I think the low down bog at low rpm is a quirk of the Big Bang V4. You have to put on some revs, feeding in the clutch, to get her going. I find VFRs need to be in the 3000+ rpm range to be comfortable and not load the engine. 

[Warnzie]

When I say bogging, I mean when giving it some throttle, light throttle nothing happens - like it hitting a flat spot and all of a sudden it gets going

[Marooncobra]

Warnzie,

 

Are your throttle cables adjusted so there is no slack in them? Obviously there needs to be a minor amount to allow full steering without an increase In the revs but there may be too much. If too much then this would give you a dead spot in your throttle twist range where it is not operating the butterflies.