Got a strange one

[Big Jets]

ITs funny you coming back with that Rob ,my mate was at the door today with his ex gp ldv van,he put a front downpipe on it and since then ran like shit ,I told him to disconnect the cat ,sure enough that was the culprit ,big flake of crap in the cat gave it a shake to clear up the blockage and his wee sherpa was runnin like a sweetie again .Your cat could be blocked ,My bike ran fine till you gave it a handfull and it just lost power, would tick over all day long and rev but when up and running it played up .

 

[keith6233]

H1 To check the cat loosen the exhausts at the head so that the gas can escape if it runs ok its the cat,had a similar problem on a corsa.

 

[nick.ct]

Rob, when it starts misbehaving at 2K5 rpm, is that under load or no load conditions. Clearly if its independant of load its not the TPS.

Nick

 

[John Armstrong]

1997 R1100 GS. Starts and runs fine, revs without any problem. As soon as you ride the bike it gets to 2.5k and bogs down, misses and farts.

Rob, when it starts misbehaving at 2K5 rpm, is that under load or no load conditions.

That help?

 

[nick.ct]

That help?

Not really, still doesnt say if the engine is under load or not

 

[John Armstrong]

Not really, still doesnt say if the engine is under load or not

Unless you ride off the side of a cliff, how do you get above 2500 rpm without it being under load, if you're riding it

 

[nick.ct]

Unless you ride off the side of a cliff, how do you get above 2500 rpm without it being under load, if you're riding it

OK OK, does the engine loading make a difference. ie light load, just bimbling or hard acceleration away from standstill?

Feck me, this is hard work

 

[Rob Farmer]

Feck me, this is hard work

I didn't word it well. The bike will rev cleanly through the rev range while it's standing still, right through to the rev line if needed. I can pull off without any problem but as soon as the revs hit 2.5k it starts missing and farting, quickly pulling in the clutch and revving the engine all is well, let the clutch out and it bogs down again.

The ECU is flagging the throttle position sensor as the fault, clearly it isn't increasing the fuel to match the TPS. The only way I'm going to suss this is to replace the TPS to clear the faut code in the ECU. They aren't cheap though.

With a bit of coaxing, careful gear changes and the use of a few downhill roads I can get to 60 MPH but as soon as the road turns into an incline it's back to 30 Mph and hickupping.

 

[Stewart H]

So does the bike have a cat? I have had a couple of instances over the years where the cat internals came adrift and were moving about in the exhaust, under the right conditions causing almost complete power loss, stop the vehicle, gubbins falls away from the hole it was obscuring, motor revs normally, failing that cant you contact a local Tosser and swap TPS units as a test ? they only take five minutes to change over/set voltage.
Stewart

 

[the celt]

The ECU is flagging the throttle position sensor as the fault, clearly it isn't increasing the fuel to match the TPS. The only way I'm going to suss this is to replace the TPS to clear the faut code in the ECU. They aren't cheap though.

.

Rob Ive a spare TPS sitting here drop me a PM and
I'll put it in the post for you to try.

 

[Rob Farmer]

Nope. No Cat fitted.

I've set the TPS up properly and the fault codes cleared so we should be ok on that front. I've just found the HT leads got a split in it. Looks like it needs some serious TLC first and a methodical approach to finding the fault.

Thanks for the offer Joe but I'm ok now

I'd forgotten how well the 1100 rides

 

[Beak Freak]

Might be barking up the wrong tree but.....

I had a similar problem recently on my 850GS. poor performance low down coughing and spluttering but it did get going again once past that part of the rev range.

Mine was down to a blocakge in the small right angled pipe (design fault?)leading from the fuel pump. once this had been blown through/poked and prodded performance returned to normal.

I don't know but would the ecu think that the throttle sensor was at fault if there was too little go juice getting through?

Sorry if I have wasted your time, but the symptoms sounded similar.

 

[Wrigsby1]

I've had 2 misfiring probs, one on a K11 and one on a GS which were both coils. The 1st was on the K and i tried all "the other things" before trying a coil. On the GS it was one of the 1st!

Motorworks were great in sending me 3 or 4 bits that might fit the bill but refunding me on things not used so for the home mechanic who is chasing their tail with a hot multimeter they can be a great help. One thing at a time mind!

The K was misfiring badly on one pot over about 3k rpm but not showing out of spec coil readings and sparking well when cold and static.

Worth a try with them to at least eliminate a few things...

G