Help! My stock GRiSO 2014 refuses to stop hunting

Friends, I really need your help here. Despite two weeks of trying different stuff My GRiSO 8V 2014 (3000 km, totally stock) refuses to stop hunting on a steady throttle. Now I’ve run out of ideas.

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Good to know: Acceleration is fine. Idle is nice too. No error codes in the ECU. I am using GuzziDiag V0.46 and Writer V0.21, by the way. Unfortunately, the hunting is inconsistent; sometimes it runs really well but a few minutes later it’s back to eternally tugging at the leash. All revs (also  above 5000 rpm, quite clearly actually) and small throttle openings.   I also have a feeling that it’s often better right after downloading a new map, which has caused me more than once to think “problem solved”.

What to try next? I’m hoping you’ll tell me to check connector x, or measure sensor y.  Something like that.

Stuff I think can be ruled out (each changed in isolation and re-tested)
• Rider induced – I know you guys will suspect this, but I’ve tried changing knee grip, position, relaxing, comparing with other bikes. No difference and only perceiving hunting on the GRiSO. (I’ve been riding sports bikes for 35 years by the way)
• Throttle cable tension – various degrees of tightness tested. No difference. (smooth action)
• Valve clearance – workshop set it at 0.20/0.30 mm , I changed it to 0.10/+.15 mm.  Had a skilled friend check it too. No difference on hunting.
• Throttle balance – TB sync done four times, with a brand new Carbtune and strictly according to Pete’s instructions. No difference on hunting.
• Air leaks – rubber boots tightened, inlet manifold sprayed with starter spray on idle. No difference on hunting.
• ECU map – several maps tested, thanks to Beetle’s eternal patience and support. No difference on hunting, while overwhelming  evidence suggest that Beetle’s Factory 294C map does not produce hunting.
• CO trim value – several positive (up to +15) and negative settings tested on most maps. Affects running but makes no difference for hunting.
• Butterfly connecting rod messed with – the yellow paint seems undisturbed (so does the throttle stop screws)
• Spark plug caps – stocks seemed to work, changed to NGK SB05E. No difference on hunting.
• Spark plugs - changed to NGK iridium. No difference on hunting.
• TPS reset - I always do “Pete’s double reset” and end up with 4.6 (most often from 4.7 when not having touched anything since the last time)
• Autolearning -  has been reset every time I change maps.
• Clogged TBs – oil level has never been above the half full mark.
• Bad petrol – I have tried three different suppliers (best quality is 98 RON with 5 % ethanol. No difference on hunting.
• Temperature induced – I’ve ridden in temperature ranging from +8C to +15C, in dry and in wet conditions. No difference.

So that’s why I am starting to think that there’s a sensor, connection or cable somewhere which may cause this. Before I start messing randomly with things, do you have any suggestions?

Cheers Olof

Valve clearance, something to which the 8V is absurdly sensitive, should be 0.15 inlet-0.2 exhaust. I know it's hard to believe but that 2 thou makes a huge difference!

Have you or the shop messed with the throttle linkage rod or either of the throttle stop screws on the TB's?

Mark was asking me about this bike. It's obviously very hard for us to be able to solve a problem like this from such a remote location but we'll try.

Pete

Olof I have seen this myself. Turned out to be a dodgy USB connection on the laptop I was using for GuzziDiag and Writer. Laptop died and has now been replaced. I found that reloading the map after this type of event usually fixed it. Worth a try

That's very interesting Tony. You thinking some corrupted bits?

Pete, the valve clearance needs some clarification. I've been saying 6 & 8 thou, or 0.1 & 0.15 without even thinking about it, but 8 thou is actually 0.2mm. I may have been inadvertently sowing the seeds of confusion myself.


Olof, you could also try reseating the connectors on the ECU. If you cannot find anything wrong elsewhere, I have a spare ECU I could send you to try.

Basically 40 thou to a mm, (give or take something so tiny it isn't even worth thinking about!) so 4 thou =0.1, 6=0.15, 8=0.2 etc.

Pete

corrupted bits indeed. Also very similar to the 1200 Sport I "adjusted" at the Budgie. new map does wonders. Might be better to send him a map again so it is a known clean one. Remember the issues I had at one stage with my ISP? Safe to reload... just to make sure.

I used to have occasional issues with my old laptop which was running XP. The new one is running the excreble Windoze 8 which drives me batty but everything *Seems* to work.

For all of those people in the modern world I apologise for still talking in Imperial measurements from time to time. I was a child who grew up during the change to decimalisation of *everything* virtually in the UK which means I tend to use whichever system of measurement I find most convenient. That means tiny stuff like valve clearances I think of in thousandths of an inch and torque figures in ft/lbs but for most stuff I use metric. Sorry if this is confusing, I'll try and pay a bit more attention in future.

Of course if you Yanks would only catch up to the eighteenth century it would make things a whole lot easier....:p

Tony, we've already tried that. I sent him a link to download a map, but it made no difference. We've also tried about 6 different maps. Even a stock map with only lambda switched off.

A corruption during flashing may be occurring. However, I find it odd that it only causes 'hunting' and not some other issue.

Re set the valves to 0.15 inlet and 0.2 exhaust for starters. Remember what a pig my thing was when I tried 0.1 and 0.15? I don't remember it 'Hunting' per-se but it was a right pig of a thing. Changing it back to the wider specs changed it back to its usual buttery self immediately!

Also, this is a roller bike isn't it? How many roller bikes are running this map? I'm pretty certain the roller cam mimics the flat tappet cam very closely but how closely? I've really got to get on to converting mine......

Pete

Hi guys, i've always thought hunting is when you close the throttle and the revs don't drop off, RIGHT, or are you meaning something else.

WAKEY.

Hunting: a consistent change in rpm up/down during steady throttle cruise.

Pete Roper wrote:

Also, this is a roller bike isn't it? How many roller bikes are running this map? I'm pretty certain the roller cam mimics the flat tappet cam very closely but how closely? I've really got to get on to converting mine......

Quite a few, actually. This issue with Olof's bike is the first with hunting. Off the top of my head, there been about 4 bikes that have had unexpected results with the 294C map, fixed with either a CO trim or custom map. We've tried several custom maps with Olof's bike. What finally hit home something was amiss was when he tried a stock 03 map with only lambda turned off. Still hunted. Irksome!

Thanks Beetle.

Wakey.

If it's still misbehaving with the -03 map, with or without Lamda on, then there's another issue. If it's appreciably worse with lamda off then once again valve clearance needs a look.

Be interesting to get to the bottom of this. I'll give it some more gogitation on the drive down to Bussleton, where hopefully beer is cheaper than in fucking Perth!

Pete

Does the GRiSO have a fuel filter (might be a dumb question...)? I had similar issues on a Kwaka 1400GTR and turned out to be a blocked/dirty fuel filter after I copped a tank of bad fuel. Cleaned the filter and problem solved. Just a thought.

Josh.C wrote:

Does the GRiSO have a fuel filter (might be a dumb question...)? I had similar issues on a Kwaka 1400GTR and turned out to be a blocked/dirty fuel filter after I copped a tank of bad fuel. Cleaned the filter and problem solved. Just a thought.

A good thought. It does have a filter. It's attached to the fuel pump assembly.

Hi all,
Thanks for engaging! I spent the morning following your suggestions so far, except for the fuel filter. Unfortunately no success.

First, to clarify, this is how I define my "hunting": when hot a persistent, non-regular variation in power, as if the engine hesitates just a little bit for a fraction of a second. It's not on/off and the engine does not cut out entirely. Imagine a V8 with one cylinder misfiring every now and then. Or imagine walking a dog which keeps the leash just stretched out, which creats a gentle, irregular and persistent tugging. When cold (engine oil temp below 70-80C) it's plain jerky.

Also important, I think - my hunting occurs at all revs and gears but only at consistent speed and at small throttle openings (up to 12-130 km/h). As soon as I twist the grip just slightly more the engine "steadies" itself and produces creamy linear power. Very nice. As soon as I ease off, the hunting returns.

So this is what I did this morning:

1. Re-adjusted valve clearance to 0.15 inlet / 0.20 exhaust and re-did TB sync including TPS reset, CO trim zero: no difference in hunting but I think it's nicer on acceleration.
2. Re-loaded Beetle's Factory 294C map using a different USB connection on the laptop and reset TPS, CO trim zero: no difference in hunting.
3. Loaded Beetle's custom map 132A and reset TPS, CO trim zero: bike significanly smoother on trottle, bordering on mushy. No difference in hunting.

So the next step you guys suggest seems to be fuel filter, right?

Cheers
Olof

If when you roll the throttle on, you get good acceleration (creamy linear power), wouldn't a bad filter exacerbate this issue? Just thinking out loud.

If you pull the tank to check the filter, disconnect the power to the pump and crank the engine for a few seconds. This will ease the pressure on the (ahem) 'quick disconnects'.

You have looked at the OBD and there are no stored or active codes?

I don't think its fuel filter simply because you'd expect a blocked filter to get worse with more throttle.

Try firing up Guzzidiag and looking at the throttle angle when you move the twist grip. Is there any point where the voltage goes haywire at or around the point your engine is hesitating? It should increase smoothly all the way from closed to fully open. Engine shouldn't be running for this obviously.

-The map gets written ok or not. It checks the checksum after writing.
-spark plug caps or the wires?


This is a new bike, so the dealer should solve it. There could be an production error outside what we think of.

Can you produce the error while in neutral holding revs at fixed position? Or only during running?
Else visiting a dyno, where you can simulate it and they can measure some things.

Pete,
Thanks. There are no stored faults, I checked again just to be sure. However, when looking at the throttle angle (yes, with engine off    ) I see the following:

When increasing the throttle GuzziDiag indication show linar changes in increments of 0,1 degrees, exept for around values of 5,6-6,0 where it jumps straight to values of 6,6-6,8 without showing any values between even if I twist the grip very slowly and carefully. Most often I see jumps from 5,8 straight to 6,8, but sometimes jumps from 6,0 straight to 7,0. I tried up to 14 degrees but only saw such jumps in the 5,6-7,0 range.

When decreasing the throttle it behaves in the same way, linear in 0,1 steps except for at 6,1-5,9, where it jumps straight to 5,2 (I don't think I saw any other value).

I disconnected the connector (three point connector on top of the right TB) and put it back with a light smear of dielectric grease, but the throttle angle indication behaved exactly the same way after that.

Verdict?

Well, that's probably the smoking gun. Warranty the TPS.

Pete

Great, thanks!!
Olof