Intermittent misfire

[francisjonno 2]

Hi Guys

My '97 Highline seems to have an intermittent misfire.

The problem only happens when the car has been run, then the ignition turned off, then restarted again after a couple of minutes (e.g. stopping at a petrol station). It misfires just below 2000rpm (worse under load), slowly clears as the revs rise and the misfires slightly around 4500rpm. Turning the ignition off then restarting always cures the problem

My local independent VW specialist pluged it into the diagnostics and it didn't come up with any problems. I've replaced the plugs and HT leads and otherwise the car runs brilliantly. The problem only happens under the specific conditions i mentioned and there's nothing majorly wrong as its just been on a rolling road and produced 199.8bhp 215.7lb ft (172bhp, 177.9ld ft at the wheels) - and is standard (as far as i know) other than a modified airbox and K&N panel.

I'm thinking it could be an intermittent fault with the lambda sensor, has anyone else had a similar problem? or any suggestions before I buy a new sensor (c.

[sijo 0]

mate if it's getting 199.8 bhp and 215.7 lb ft I really wouldn't worry, as it should be 174 bhp at the wheels, not the flywheel !

[francisjonno 2]

I know, it was a surprise when i got the printout! I thought the guy ment it was 172 at the flywheel but he promised it was at the wheels and had just checked the rollers against a car that had recently been on AMD's rollers (it produced the same bhp both times)

Trouble is, when the problem happens and i'm trying to overtake it feels like the engines fallen out and its got 20bhp!

[Guest sleeper]

Lambda probes should be considered a 'service' item. Their expected lifespan is 40-60k according to bosch & siemens. Allegedly they can be cleaned, the hard bit is getting them out... good luck!