bad running uder acceleration

[MiataMark]

Got an issue with my MX5 which I find hard to explain, basically when you accelerate there is a lot of what sound like exhaust blow noise and it feels like there is resistance to acceleration. The closest I can come to is that it is similar to when I had EGR issues on my diesel Alfa.

No fault codes show on the admittedly basic diagnostic port.

The car did initially fail an MOT on erratic idle that the garage put down to the Idle Speed Control, a good Italian tune sorted that out. I've taken the air Valve off and given it a good clean which I think has improved things. Which potentially leaves the Idle Speed Control Valve (which is expensive and should show as a fault on the diagnostics as it's electronically controlled, or there is a sensor).

There is another worry, I've never been that happy with the cooling system on the car and the water level does seem to drop, could there be a HG issue? I haven't had time to either check the oil filler and do a compression check. Can't see any oil in the water but it's so rusty that I'm not sure you could, needs a good flush through.

Anybody with MX5 engine experience got any hints...

[kevins]

With all these things its best to get back to basics:

Does it have compression
Does it have a clear air path (air cleaner, catalyst or muffler blocked, ducts collapsing, throttle fully opening, air leaks post MAF)
Ignition- do all the plugs look OK and the same, coil packs and leads could be breaking down.
Fuel - is the fuel pressure OK, does it drop at high load, is the filter blocked, colour of plugs will also tell you if it is running weak or rich.

These are in that era when the on board diagnostics was pretty useless and testing parts on the bench is not easy, diagnosis largely falls down to replacing parts, if you can find someone with a similar car swapping things like MAF, coilpacks etc is an easy way to rule out components without spending a fortune.

[MiataMark]

Been to a local garage (that did the MOT) diagnosed as miss-firing probably ignition. I've ordered new plug leads and plugs as I was going to renew them anyway.

[Rich]

Jul 25, 2019 21:25:39 GMT MiataMark said:

Been to a local garage (that did the MOT) diagnosed as miss-firing probably ignition. I've ordered new plug leads and plugs as I was going to renew them anyway.

Plugs and leads were moderately common on the MX5, the one I bought for the engine misfired from cold until it had been driven for a good few miles, new plugs and leads sorted it a treat.

[MiataMark]

Jul 25, 2019 21:52:13 GMT Rich said:

Jul 25, 2019 21:25:39 GMT MiataMark said:

Been to a local garage (that did the MOT) diagnosed as miss-firing probably ignition. I've ordered new plug leads and plugs as I was going to renew them anyway.

Plugs and leads were moderately common on the MX5, the one I bought for the engine misfired from cold until it had been driven for a good few miles, new plugs and leads sorted it a treat.

Good to know, I was going to change them anyway so will be good to see if it makes a difference. I'll do compression check as well, if I can find my gauge.

[CFmania]

bad running uder acceleration.

So the cars not Moo vin too well?

[ChasR]

Is it misfiring or just making alot of noise instead of moving along?

If it's running smoothly, I'd say its a blocked catalytic converter or a fuelling issue.

[MiataMark]

Aug 24, 2019 6:55:45 GMT ChasR said:

Is it misfiring or just making alot of noise instead of moving along?

If it's running smoothly, I'd say its a blocked catalytic converter or a fuelling issue.

It was fixed with new leads and plugs.