TONY55S said:

do the map sensors fail .my car is 19 years old with original sensor.
is it worth buying new one in the hope it will fix the misfire.
tony

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A poster has already suggested it could be the map sensor. You can at least check it is clean. It is a simple part. Failure is going to create a code.

Have you checked the codes?


Meanwhile you seem to be ignoring repeated requests to you to find out if you have checked the ECU earth.

Have you scraped it yet? Can I bagsy the fuel rail please.

judderbar said:

Have you checked and cleaned up the ECU earth wire? There should be an earth wire from the ECU to the throttle body because the ECU is bolted to the plastic inlet manifold.

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Even if it's an old post, maybe the below info could help others searchers, as I am.

A little completion : the first 'end' of ECU earth BLACK wire is bolted on the throttle body (metal to metal), and the throttle body is bolted indeed on the plastic intake manifold. The other end of the earth wire is bolted under the engine, in the starter motor zone. Of course, the engine (and the starter motor) is linked to the gearbox, which is linked to the chassis, which is linked to the negative from battery.

A quick test for ECU earth is to create a new link directly to battery minus with a serious enough cable from one of the 2 ECU bolts. Especially when we cannot check in the parking the ECU earth under the engine...

A missfire will always cause the plugs to become sooty which aggravates the problem. Misfires put unused oxygen down the exhaust. The ECU sees this as a weak air/fuel ratio so turns up the fuel - result black spark plugs.

Start the car from cold or near cold and point an IR thermometer at the exhaust stubs. Missfiring cylinders will be cooler than the others. The 8V has two coils so it's likely that 2 & 3 or 1 & 4 will be similar.

It will be electronic ignition so the ECU will save and last good or bad running information,. Take the earth and live lead off the battery and connect them together overnight this will reset the ecu,. Basically it will wipe the ECU,. Once it's been 24 hours put the earth and live lead back on the battery and then turn on the ignition but do not start the car for at least 5 minutes let the ECU pick up all the sensors ect