Occasional hesitation/loss of power at 5000rpm+

[172_Tom]

Sometimes when I get to 5000rpm the engine seems to splutter a bit and loses power. Only happens infrequently. Engine is definitely well up to temperature when it happens. Car recently passed its MOT. Timing is definitely not out. Oil level is fine. No warning lights on the dash.

I'm planning on servicing it soon and changing the plugs. If changing the plugs doesn't work where should I be looking next?

 

[Clioste]

I had this all the problem was that one lead was bit dodgy changed em and runs fine.

 

[172_Tom]

OK cheers, were there any visible signs on it or did you just follow a process of elimination?

 

[Clioste]

Well that was first thing I tried not saying it is that but it worked for me when I tryed booting it at high rpm didn't want to know or oxy sensor maybe.

 

[MartinR]

lambda sensor pre cat

 

[172_Tom]

lambda sensor pre cat

Wouldn't it have failed the MOT on emissions if the lambda sensor was bad?

I changed the plugs at the weekend - old plugs were Bosch ones and I've replaced them with the correct NGK ones so hopefully this will cure it.

 

[basketballjoe3]

I had something similar to this in mine about 6 months ago, turned out to be the coolant temperature sensor and/or thermostat (not sure, changed both).
Nothing else happened at first, and I just slowed down/stopped booting it and the power came back/hesitation stopped.

The give away for mine though was that a couple of days later the temperature gauge started hitting zero when it happened too.