How to solve hesitation, missfires and flat spots

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[url=https://imoc.co.uk/app.php/kb/viewarticle?a=22&sid=d52044e1db0a41fd0b701a54b29a01bd]Knowledge Base - How to solve hesitation, missfires and flat spots[/url]

This comes up a lot so I thought I would do a little write up on it. Feel free to add to this if you feel I have missed something out!

Hesitation and flat spots are generally caused by poor ignition components. I have recomended things to check in the order that they are likelyest to be and the cost of replacement.

1. Check the distributer cap and rotor arm. (see separate how to for replacing them) If the contacts are heavily corroded or damaged replace them. Check for signs of oil or water in the distributer cap. Whilst you have the cap off.....

2. Check the state of the connectors on the HT leads, look for corrosion or damage to the contacts again.

3. Check the state of the ht leads in general, look for splits in the leads, kinks and check the connectors at the spark plug ends.... whilst you have the ht leads out.....

4. Check the state of the sparkplugs.... look for wear on the electrodes, damage or discolouration

5. Check the airfilter.... replace / clean if dirty

6. Check the ecu for error codes and perform an ecu reset.

If these all look ok but you still have a flat spot I suggest:

1. Replace the dizzy cap and rotor arm first (around £20 for the pair from mrT)

2. Replace the sparkplugs next (NGK\'s cost about £8 for 4 from unipart)

3. If the problem is still there try some injector cleaner

4. I suggest changing HT leads last of all as these don\'t tend to fail very often and are very expensive to replace!