Hey All
Hoping you guys can help me with some suggestions for an ignition issue I'm having!
I've done some searching across here and the Miata.net forums- wanted to see if my hypothesis was on the right track before I start ordering replacement parts.
Car
1990 NA 1.6 (Short-nosed crank)
Problem
Misfiring/hesitation
Symptoms
Not much when cold- seems to idle quite high, between 1000-1200 rpm.
As the car starts to warm it begins to hesitate with a misfire on acceleration, especially below 3000rpm.
Once up to temperature, if you're sat at a set of lights out of gear, without your foot on the clutch, the idle becomes very sporadic and you can hear it misfire- it sometimes gets to the point of wanting to stall. Pulling away requires a very light foot, else you'll end up with it misfiring and barely moving, even when you go through the gears. Once it's moving though, I can knock it down to 3rd at around 50mph and it'll accelerate cleanly going through the gears.
Occasionally- if you're pulling away with it misfiring, it will sort itself out with a noise that I can only describe as a 'clank'. It's not massively intrusive, but you'll hear it coming from around the bulkhead, near the coil pack. Doesn't happen all the time though.
Factors
The car wasn't very well looked after by the previous owners- it had developed an oil leak from the CAS sensor at the back of the block and as a result, the engine was covered with an oil/muddy residue, especially near the bulkhead- I'm thinking this has finally killed the coil pack. The wires aren't original and don't seem the best quality, the length alone is wrong. I did have a look under the bonnet with the engine running in darkness and I can't see any flashes or signs of arcing, but it could be happening in the plug chambers itself.
I'm pretty sure a change of leads and a new coil pack will sort it, but as I've already replaced most of the cooling system over the last month I can't really afford to be wrong!
I've read a few other posts that says it could be throttle body or a variety of sensors. Are there any other things I can do (cleaning electrical connectors, testing etc.) before I start buying up parts?
Thanks again guys, apologies for the war and peace!
ZB.
Hoping you guys can help me with some suggestions for an ignition issue I'm having!
I've done some searching across here and the Miata.net forums- wanted to see if my hypothesis was on the right track before I start ordering replacement parts.
Car
1990 NA 1.6 (Short-nosed crank)
Problem
Misfiring/hesitation
Symptoms
Not much when cold- seems to idle quite high, between 1000-1200 rpm.
As the car starts to warm it begins to hesitate with a misfire on acceleration, especially below 3000rpm.
Once up to temperature, if you're sat at a set of lights out of gear, without your foot on the clutch, the idle becomes very sporadic and you can hear it misfire- it sometimes gets to the point of wanting to stall. Pulling away requires a very light foot, else you'll end up with it misfiring and barely moving, even when you go through the gears. Once it's moving though, I can knock it down to 3rd at around 50mph and it'll accelerate cleanly going through the gears.
Occasionally- if you're pulling away with it misfiring, it will sort itself out with a noise that I can only describe as a 'clank'. It's not massively intrusive, but you'll hear it coming from around the bulkhead, near the coil pack. Doesn't happen all the time though.
Factors
The car wasn't very well looked after by the previous owners- it had developed an oil leak from the CAS sensor at the back of the block and as a result, the engine was covered with an oil/muddy residue, especially near the bulkhead- I'm thinking this has finally killed the coil pack. The wires aren't original and don't seem the best quality, the length alone is wrong. I did have a look under the bonnet with the engine running in darkness and I can't see any flashes or signs of arcing, but it could be happening in the plug chambers itself.
I'm pretty sure a change of leads and a new coil pack will sort it, but as I've already replaced most of the cooling system over the last month I can't really afford to be wrong!
I've read a few other posts that says it could be throttle body or a variety of sensors. Are there any other things I can do (cleaning electrical connectors, testing etc.) before I start buying up parts?
Thanks again guys, apologies for the war and peace!
ZB.