- My model of MX-5 is: Mk1 1.6 Auto Import
- I’m based near: Northwest
- I’m looking for technical help or recommendations on:
Hello everyone, new to writing on this platform but I’m at a bit of a loose end and am looking for recommendations/help.
I have a 1.6 automatic imported mk1 with a very strange misfiring issue.
If I apply harsh acceleration it misfires heavily up to 2k revs and will not climb higher, however if I very gently accelerate and get the revs above 2k I can then use as much throttle as I like and it drives like normal again, it does this regardless of whether the overdrive is turned on or off.
I have replaced the spark plugs, HT leads, checked for water in the spark plug wells, tried driving it with the o2 sensor unplugged, replaced the fuel pump wiring that I found had been chewed by a mouse, checked the throttle position sensor with a multimeter, the air flow meter is also completely free and not seized.
So I’m looking for:
A. If anyone has experienced similar and what they did to rectify the issue.
B. Peoples ideas on what may cause an issue like this one.
All help and ideas are greatly appreciated,
Thanks,
Ros 
May I suggest you check the fuel lines and filters for internal damage and blockages?
Your car’s symptoms strongly remind me of a similar problem I had many years ago with an old Mk2 Zodiac.
It was intermittent fuel starvation, but only under certain conditions.
Fortunately those cars were very, very simple, with not many places to check for problems.
It turned out that a flexible rubber fuel pipe from the body to the engine had a tiny flap of rubber loose inside where the rubber had been clumsily pushed over the end of the metal pipe from the tank (not by me and also a major reason why I got the car really, really cheap).
The sharp edge of the metal tube had shaved that piece of rubber so that at a high flow it partially blocked the pipe, BUT only when the engine was leaning over on the engine mounts when cornering hard and/or at max throttle. ie typical student driving.
A temporary fix was to replace the rubber with a bit of plastic reinforced fish-tank pipe. Alas, that soon became hard and cracked with a strong pong of petrol…
The correct type of rubber pipe was the cure, and fitted very carefully worked well for another couple of years before I lost the rust battle that finally killed my old faithful. That car was where I made most of my mistakes while learning to weld…
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