My uncles having problems with his little rover 25, He says that when he is driving around town the engine missfires and judders when he lets off the throttle ie coasting in gear. He says that sometimes its been missing on acceleration aswell but not so bad. To date hes had crank sensor fitted and o2 sensor by local garage..but problem is still there

anyone help pls?

2000 1.4 k series rover 25

thanx

If its got coil per cylinder ignition have a look to see if the plug leads are rubbing on the cylinder head and shorting out. Just one idea, I am sure others will follow.
Steve.
Edit.
PS I have got a set of new coils if that turns out to be the problem. Also a new crank sensor.
Steve

[Edited on 19/4/10 by stevec]

No rover specific knowlage but for missfiring, a new plugs and coil?

Its either spark for fueling isnt it, so if the cps is ok and the 02.
- What do the plugs look like? Spark?
- Garage could (or might have) stuck a emissions probe up it.

Start with the basics, it's most likely ignition related.

IIRC a MY2000 Rover will still have a distributor, so the rotor arm, distributor cap and HT leads should all fall under suspicion, as should the spark plugs if they have not been changed according to the service schedule. Coil is also a possibility.

[Edited on 19/4/10 by MikeRJ]

thanx for your help guys

Year 2000 was the change over point from distributor and single coil to 2 coil wasted spark , about 2002 they switched to 2 plug top coil packs.

As above replace the rotor arm or on latter cars coil packs and fit new plugs either X-part or NGK.
NGK number BKR6E or BKR6ES *** very ***important to
check the plugs are gapped at 0.8mm for distributor models. Cars with coil packs used a 1.1mm gap but I recommend the gap is reduced to 0.8mm

However you can also do a few simple checks before spending money.
(1) I think the car will be fitted with a Mems 1.9 or 2.x ecu which has the MAP sensor fitted to the ECU motheboard.
The small bore vacuum pipe between the throttlebody/inlet and the ECU manifold should be **very** carefully removed at both ends and blown through, I would not be surprised if it is full of gunge or liquid.

(2) Re-synch the throttle position sensor to the ECU , by this procedure: with the ignition on but engine not running push the throttle pedal slowly to the floor ten times, then turn ignition off and start the engine.

(3) Check the inlet manifold is tight.

(4) The the earthing point for the MEMS ecu is making good contact with the chassis --- I think on this model the ECU is in front of the battery and the earth point is somewhere on the bonnet landing panel or front ns wing.


(5) Also check the throttle position sensor they can wear badly between idle and 1/4 throttle as this part of the movement gets he most wear.