misfire in one exhaust pipe on idle

[eng622]

On test driving a car I was looking to buy there was a slight hesitation at low revs when giving it some throttle. On return I noticed that the OS exhaust pipe had a smooth beat whilst the NS one had an irregular beat and the occasional misfire. Could this be a faulty oxygen sensor (lamda). I'm making the assumtion that there is one in each outlet pipe as I have read there are two sensors.

[yzf1070]

Yes there is a lambda in each exhaust and both exhausts remain seperate all the way to the back of the car. The reason for the misfire could be a multitude of things but not necessarily anything seriously untoward. First items that spring to mind other than lambda are the plugs, plug leads, ignition coil pack, collapsed cat, one cylinder running lean.....the list could go on. On a worse case it could be a burnt exhaust valve. You mention that the car hessitates at low revs under acceleration.....my limited knowledge would lead me to first suspect a Lambda sensor as these are notorious for failing. There are very simple ways to test for this but as the car is not your possesion its not practical to do in this case.


A little more info for consideration. If the car hessitates regularly under accelleration mid range my first guess would be throttle body spindle wear. The proper way to sort this is to have the bodies reworked with brass bushes, or you can get reworked exchange items. However this issue so far seems to affect only the earlier cars (sub 2003).

You do not mention mileage and age of the car so its difficult to be more precise.

My recommendation is to ask the owner (if private) or the dealer/garage to get it sorted and he/she is in more of a position to receive the deal/sale they are seeking.

Good luck

G

Edited by yzf1070 on Wednesday 22 November 08:46

[rralston]

Could be many things although I've had a similar experience with mine last year.

Turned out to be the Catalyst, it had broken down on one side, and got lodged in the central silencer.

Started as a misfire, then a cronic lack of power.

Quick Answer - remove cat material and refit exhaust.

[eng622]

The Tuscan was an S 2003, with 15K but had not been used regularly for two years. I have a Fiat Coupe 20VT and that developed a misfire and all it turned out to be was the Lambda sensor.