Hi, I am new to the forum and unfortunately have to ask a question right away.

I have a Mondeo Mk2 1.8 Zetec Estate (1998) and started to notice a slight juddering and hesitation when accelerating so I went ahead and bought new spark plugs. Got them at Halfords, looked at the booklet they have there to make sure I get the correct ones. Bought the recommended Bosch ones and changed them this afternoon. The old ones were kind of rusty and didn't look good at all, so I think the change was really necessary. Unfortunately now the car is even worse, really rough idle and hops like a kangaroo when I accelerate. Now....did I do something wrong just by changing the plugs?

Any suggestions much appreciated.

Mel

Did you check the gap was correct?

Did you check the gap was correct?

Ahh, no, didn't do that. The new plugs are not the single electrode ones, they are the Super 4 ones. Would the gap adjustment be the same? I assume I could find the right gap setting in the Haynes manual?

I would think the gap should still be the same.

Yeah Haynes will state what the gap should be. If they were bought for your car/engine then they should be pre gapped but worth checking.

Are the ht leads in good condition?

if the gaps are not the issue, then you should be checking the HT leads and Coil Pack. If the HT leads have been moved around, you could have broken them inadvertently. The HT leads settle in one position for many years, they become fragile and the slightest disturbance of their comfort can brake the wires inside. The Coil Packs also if they are failing can cause this issue. any loose water in the engine bay can run down the leads and seep into the coil packs.

I would say check the gap first, then if this fails, buy yourself new HT leads and see if that makes a difference, it likely will make some improvement, but if its still running like a spanner then the Coil Pack is where my money would be.

Thanks for the replies guys...Problem is solved...the car really didn't like the spark plugs I got.

Bought another set from NGK with the single electrode instead of the 4 on the Bosch ones and hey...car is purring like a kitten.

Thanks for the replies guys...Problem is solved...the car really didn't like the spark plugs I got.

Bought another set from NGK with the single electrode instead of the 4 on the Bosch ones and hey...car is purring like a kitten.

Good result

Excellent, hopefully it wasnt too expensive overall?