S4 won't rev past 6000rpm ???

[br1an]

Before I go and spend £100s on getting my bike diagnosed, has anyone had similar problems as this.

My bike is a 2001 S4 Challenge and I've owned it for 4 years with no problems, but now as I accelerate up to 6000 revs it just seems as if there is a rev limiter. If you hold it back against the throttle stop it refuses to go past 6000, but if you back it off it will climb past but no were near as fast as it should do??

Something else I've noticed is when your running at a constant speed it seems to be missing, not exactly running on one cylinder, but definitely not right.

I have 2 ecu's the standard and the race and it makes no difference which one is fitted, and I've changed the spark plugs for NGK ones.

The only other thing that has happened is when it was in my garage the top box off my car dropped on it and I'm wondering if this has moved some throttle position thingymidgig.

If anyone has any ideas they would be much appreciated as It' ruining a fantastic bike.:hissy:

Cheers
Brian.

[br1an]

Does no one have any ideas on this ??????

Cheers
Brian

[Gilps]

Blocked air filter?

[br1an]

The bike has the DP open air filter fitted.

I think it's something more electrical???

Bry...

[jerry]

Yeah but when was it last cleaned ?
worn rockers?
TPS out ?
Coils ?

[S4 MAD]

as said by jerry tps gave me all kind of probs when mine went up the shoot.:(

[br1an]

as said by jerry tps gave me all kind of probs when mine went up the shoot.:(

Thanks for the replies, but could you expand on the the tps thingy ? When I look at the top of the engine from the left hand side is that the black square flat thing about 4cm across with yellow marking paint on the screws ?

I have the Ducati workshop manual but all it says about the tps is that it needs plugging into the mathmoss and it should give value xxx.

How did yours go wrong and what were the consequences ?

Cheers

Brian.

[jerry]

Yes the TPS , (throttle postion sensor )is what u are describing it can be adjusted without Mathesis if u have a good Digital multimeter and Balance kit for balancing the injectors as well as one affect the other. Or take i to a dealer for checking.They can go out of adjustment over time I check mine every 3 months or when i check the valves. usually low speed running shows up problems but at higher speeds I would not be so sure>

[bod]

Or why not mark the standard position yourself and then loosen the holding screws and give it a turn either way by a few % it's only a variable resistor nothing to clever.

[jerry]

it is very sensitive and not easy to get spot on u need much patience and the hand of a brain surgeon.

[br1an]

As a final update to this thread and hopefully this will help someone in the future.

The problem I had with my bike was rust in the fuel tank that caused sediment to build at the bottom . This has now been sorted with a good clean out and sealing with Petseal. I fitted a new fuel filter and now the bike is back to it's naughtiest best.

Does anyone know where to get a set of Timing belts for a S4 for less than £75.

Cheers

Brian.

[jerry]

My S4 in thailand has developed same fault and i am 90% sure its the fuel filter as well,