bad misfire

[GlennyGills]

Hi ,
My 95 Mk1 1.8 has a recurring problem. When staring from cold it idles ok, but when I try to pull away it misfires severely for a couple of minutes then all seems ok. This evening after I got home I put the MX5 Tech Diagnostic box on to test it and I got my usual Atm pressure error. No other faults.
BUT when i switched it to REV IDLE to was very bad and misfiring. Switching back to Rev Free and all seems well.
I did try revving it and I got what I thought was perhaps a slight misfire.

When driving I get some exhaust smells in the cab, dont know if it is related or not

I pull off the leads from the coil packs and the plugs and re seated them.

Any thoughts where to look?

Thanks

[blackyb]

Just asking, once warmed up, does the misfire clear altogether.

[GlennyGills]

Hi Bri,
I hesitate to say yes, but if still there not really noticeable.
Will check tomorrow.

[GlennyGills]

Strange thing - this morning it started and ran fine. Mazdamenders remote repairs - perhaps??

Wait and see

[GlennyGills]

Spoke a bit too soon, after being left in underground parking the car starts fine but struggles to run, bad misfire. After a couple of minutes all okay.

[Mazda Mender]

I am sure I posted up on this ????
Check for any dodgy wires to the coil pack,bent pins in the connection plugs, furring/tarnishing in the coil pack pots, split or crack in the coil pack, split in the HT leads, furring or tarnishing on the HT leads connections, oil,water in the spark plug wells ,or the lighting makers themselves

[GlennyGills]

Hi Wayne, thanks for the check list. I will do it tomorrow.

[blackyb]

Sounds similar to a problem I had years ago with my mk1 Escort. Fine during the summer but did exactly what your MX is doing come the damper winter months. Miss fire on first start up but once she got warm miss fire cleared. Turned out to be a damaged HT lead. Inidentified at night, bonnet up, started the car and I could see the flash of a spark from the HT lead.

Hope your fix is as easy as mine was back then.

[GlennyGills]

Well I think I have found my misfire problem.
New leads ordered from Autolink..
Just a note.. I had to peel back the rubber cover to see the extent of the problem. Cleaning the terminal made the problem better but didn't clear it.

16682624571726713948484890243993.jpg (332.25 KiB) Viewed 1196 times

[blackyb]

Moisture, hope the new leads cures the problem for you.
Putting our little girl to bed till spring tomorrow.

[GlennyGills]

Just fitted new spark plug leads- no difference.
Next to try, when rain stops, is new spark plugs.
I have bought a 4 pin 1.8 95-98 coil pack if required. Hope it is the correct one..

[Mazda Mender]

3pin 95 onwards , 93/95 4 pin
M-m

[GlennyGills]

Mines a 95
Well changed the plugs and no improvement - so coil pack change it is then. The wiring plug connectors feel difficult to remove. Can they be taken off after I have removed the three bolts and lifted the coil pack up ?

[GlennyGills]

Beaten by the bolt underneath and it starting to persistently rain.
Any hints for getting the lower bolt out.

[Mazda Mender]

12 mm ring end on the nut and use the two spanner method to crack it, and keep moving the ring and turning until it becomes really loose, if you have knuckle ratchet spanners than use it and then get you hand/fingers in to turn it out and remove it , but do this while the top bolts are still tight other wish the frame will put weight on the back bottom bolt and make it even worse to get out.
Now as for the plugs , press the tab in and use a flat driver at the bottom of the plugs and Jimmy/twist them until it braeks free from its hold and just pull it off, make sure they go back the same way as removed and the HTLeads