I have a 1999 XKR which has failed the MOT on emissions and has a slight misfire which gets worse as the car warms up.

I'm thinking maybe lamda sensors, but i've also been told it could be the coil packs which a belive is a usual problem.

Anything else it's likely to be?

 

Before you begin to speculate and long before you even think about throwing parts at it, have the codes read. Post the actual codes back here - not the descriptions anyone who reads them tells you they mean.

Please add 'location' and 'vehicle details' to your profile. It helps everyone to give relevant advice.

Graham

 

error codesas follows

P0300
P0301
p0302
p0304
p0308
p1316
p0102
p0112

I'm aware the final 2 are the air flow meter, but would this cause all the above?

 

A bad mass air sensor would absolutely wreak havoc on fuel trims...swap it over with a known, good one (or give it a good cleaning first), clear the codes, and see if any misfires return.

 

I concur. Clean your mass air flow sensor first. You can purchase a spray can of mass air flow sensor cleaner at any chain auto parts store for about six bucks. Two screws (some cars have Phillips screws, some cars have Torx screws) hold the sensor on. Once the screws are removed, unplug the sensor's electronic harness carefully, take the sensor outside, and give the inner element several thorough sprays from the sensor cleaner can. DO NOT attempt to wipe any part of the sensor dry. Wait a couple of minutes and repeat. Then set the sensor aside and allow it to air-dry for 30 minutes or so. Re-install it, clear your codes, and drive the car to see if you fixed your problem....

If the trouble codes return, it may be time for a new sensor....