Engine bogging down

[volcane]

Hi all
A friend has a 2005 GS1200 80000 miles. Accelerates fine to 4500rpm but then boggs down if given an agressive throttle input from there. Will accelerate ok from these revs with gentle throttle input. Any advice appreciated.
Best regards

 

[volcane]

Boggs down meaning decided lack of urge to accelerate up from 4500rpm in case the term causes any confusion. Is this likely coil sticks? Sticking/ loose cable or air leak? Any help appreciated.
Best regards

 

[Bendy toy]

Air leak - unlikely - Usually worst at low throttle settings.

Throttle cable - possible - check the cables where they enter the TBs and make sure both sides open fully.

TPS - Maybe - Make sure its not come loose and do the reset procedure.

Clogged air filter - Maybe - Usually worse at high throttle settings

Failing coils. Very possible - engine has a vibration phase at that speed. If its on the old black painted coils they will be well on the way out by now. Mine actually smelled burnt.

Blocked fuel filter. Unlikely - Check the fuel pump.

 

[alex_rsa]

coils....

 

[volcane]

Thanks i shall give feedback on the outcome.
Best regards PJ

 

[Bendy toy]

Easiest job is to pull the coils. If they smell burnt, get new ones because if they have not fully packed up they will soon enough.

 

[BlueBird]

Id try the

TPS,
A faulty one wont show on any diagnostics either.

 

[Greenman14]

Fuel pump? Symptoms are similar to my KTM 950 when its pump failed.

 

[volcane]

Hi
This turned out to be the R/H cylinder upper coil. We pulled the leads of the coil sticks bar one at a time. The R/H upper was the only one that would not start. Swapped over to confirm this one was at fault. Checked resistance on the outside pins which actually showed the same resistance as the serviceable one. Thanks for the suggestions. Where is the most reasonable place to buy these?

Thanks again rgds volcane

 

[alex_rsa]

Winner

Don't think there is any choice excpet BMW although Motowerks may sell genuine ones at a small discount.

 

[Bendy toy]

What colour are your coils?

Black painted are old style and not reliable. When one fails the other will do the same very soon.

Stainless steel sleeved - generally very reliable so bad luck if one has gone down. From BMW cost £80 to you sir. (each).

These are three pin coils - power, earth and trigger. You might be able to get a car coil of the right size to fit but you'll need a tame store man at a large motor factors to find the right one.

 

[volcane]

Black painted coils, will just bite the bullet and order from BMW.
Thanks again rgds volcane

 

[Bendy toy]

When mine failed I struggled to find the fault and replaced an O2 sensor. Then one went down for good and it was obvious what was happening. The dealer said they generally go in pairs and (guess what?) the other coil packed up while i was on the way home!!!

Mine actually smelled burnt.

 

[volcane]

Thanks again all
New stick coil installed bike back to full power��. Cost €108 through BMW limerick. Hopefully the rest will last a little longer. My friend has just finished finished a full maintenance schedule on a KLR 650 for an upcoming trip initially to Mongolia then much further on a follow up trip. Reds volcane.

 

[SimonB]

Just assuming.....

If the problem bike is in Kyle of Lochalsh on the way back to Oxfordshire would the panel limp back 550 miles or take the big yellow taxi? All advice gratefully received!

 

[Rocketman]

If the problem bike is in Kyle of Lochalsh on the way back to Oxfordshire would the panel limp back 550 miles or take the big yellow taxi? All advice gratefully received!

I could think of worse places for my coils to pack up .
I'd limp it back through the night with next to nowt on the road or ring carole to get me home

 

[alex_rsa]

If the problem bike is in Kyle of Lochalsh on the way back to Oxfordshire would the panel limp back 550 miles or take the big yellow taxi? All advice gratefully received!

I have had coils fail on me 3 times and never once would I have thought of using recovery.

The bike is missing-firing because of overfuelling but if you accelerate smoothly it should work just fine as the main plug will burn the complete mixture.

Cheers

Alex

 

[SimonB]

Thanks for that. It made it over Applecross with no real issues and up to Poolewe today and will head home tomorrow on a light throttle.

 

[Bendy toy]

Mine was a nightmare to diagnose because both primary coils were failing though one was slightly worse than the other. The secondaries fire so late they do very little. There is also the over rich mixtures caused by the O2 sensors which can't measure the hydrocarbon levels. Unburnt fuel = increased O2 in the exhaust gas so the ECU assumes its running too weak and ups the fuel flow. So the misfire quickly get worse as the plugs get sooty.

If you have a broken fuel strip you will need a to cary spare fuel because it will guzzle petrol and you will run out long before you would expect to.

 

[SimonB]

Once again thanks. Made it back from Poolewe on a light throttle over a couple of days and fitted a new coil. It appears to be back to normal if a little tired and filthy after 1800 miles in the last 10 days.