Pre-ignition or pinking? 2007 MX5 coupe.

Hi

Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise when
accelerating gently at fairly low revs. Not a lot of torque starting off
on steep hills in Cornwall the last few days.

Garage can find nothing wrong. Never had any similar problems with our
2005 1.8 but exhaust is quite white inside.

Anyone come across anything similar? No problems over 2500 rpm. Goes
best over 3500 rpm.

TIA for any help.

The Invisible Man > wrote:

>Hi
>
>Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise when
>accelerating gently at fairly low revs. Not a lot of torque starting off
>on steep hills in Cornwall the last few days.
>
>Garage can find nothing wrong. Never had any similar problems with our
>2005 1.8 but exhaust is quite white inside.
>
>Anyone come across anything similar? No problems over 2500 rpm. Goes
>best over 3500 rpm.

But you should not be accelerating up steep hills at less than 3,000 rpm.
It would be lugging the engine. That is why there are gears.

Leon

>TIA for any help.
--
Leon van Dommelen Bess, the Miata Bozo, the Miata
http://www.dommelen.net/miata
The only thing better than a white Miata is two white Miatas

Probably a combination of:

1. Bad fuel. Octane ratings may not be what they should at some outlets,
try a differant fuel supply
2. Carbon build up in the combustion chambers. Run a car of fuel additive
designed to flush it out.




"The Invisible Man" > wrote in message
. co.uk...
> Hi
>
> Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise when
> accelerating gently at fairly low revs. Not a lot of torque starting off
> on steep hills in Cornwall the last few days.
>
> Garage can find nothing wrong. Never had any similar problems with our
> 2005 1.8 but exhaust is quite white inside.
>
> Anyone come across anything similar? No problems over 2500 rpm. Goes best
> over 3500 rpm.
>
> TIA for any help.

Mal Osborne wrote:
> Probably a combination of:
>
> 1. Bad fuel. Octane ratings may not be what they should at some
> outlets, try a differant fuel supply
> 2. Carbon build up in the combustion chambers. Run a car of fuel
> additive designed to flush it out.
>
>
>
>
> "The Invisible Man" > wrote in message
> . co.uk...
>> Hi
>>
>> Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise when
>> accelerating gently at fairly low revs. Not a lot of torque starting
>> off on steep hills in Cornwall the last few days.
>>
>> Garage can find nothing wrong. Never had any similar problems with our
>> 2005 1.8 but exhaust is quite white inside.
>>
>> Anyone come across anything similar? No problems over 2500 rpm. Goes
>> best over 3500 rpm.
>>
>> TIA for any help.
>
Thanks for your comments.

Did wonder about the fuel but have now used 3 different brands from
outlets 300 miles apart.

White exhausts used to often mean that mixture was a bit lean.

I wouldn't expect a modern car to coke up quickly but maybe I ran it in
too gently.

30 years ago I would spend hours adjusting the mixture, balancing carbs
and trying different ignition advance/retard but nowadays I am unaware
of much that can be done other than using a not-standard chip.

Other than a road car I had long ago which I fitted with a half race
head etc. our current MX5 is the the most difficult I have ever had to
drive in traffic.

The Invisible Man wrote:
> Hi
>
> Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise when
> accelerating gently at fairly low revs. Not a lot of torque starting off
> on steep hills in Cornwall the last few days.
>
> Garage can find nothing wrong. Never had any similar problems with our
> 2005 1.8 but exhaust is quite white inside.
>
> Anyone come across anything similar? No problems over 2500 rpm. Goes
> best over 3500 rpm.
>
> TIA for any help.

You've answered your own question. Keep the revs up.

On 2007-06-25, Zog The Undeniable > wrote:

>> Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise
>> when accelerating gently at fairly low revs. Not a lot of
>> torque starting off on steep hills in Cornwall the last few
>> days.
>>
>> Garage can find nothing wrong. Never had any similar problems
>> with our 2005 1.8 but exhaust is quite white inside.
>>
>> Anyone come across anything similar? No problems over 2500
>> rpm. Goes best over 3500 rpm.
>
> You've answered your own question. Keep the revs up.

So the 2007 engine is really that much worse than the 2005?

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Grant Edwards wrote:
> On 2007-06-25, Zog The Undeniable > wrote:
>
>>> Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise
>>> when accelerating gently at fairly low revs. Not a lot of
>>> torque starting off on steep hills in Cornwall the last few
>>> days.
>>>
>>> Garage can find nothing wrong. Never had any similar problems
>>> with our 2005 1.8 but exhaust is quite white inside.
>>>
>>> Anyone come across anything similar? No problems over 2500
>>> rpm. Goes best over 3500 rpm.
>> You've answered your own question. Keep the revs up.
>
> So the 2007 engine is really that much worse than the 2005?
>
My mistake. The old MX5 was in fact a 2002 model.

Our 2007 is difficult to drive in town centre traffic. It almost needs
putting into 1st gear every time you turn at a green light at an
intersection. I have driven a lot of cars over nearly 40 years but never
had one this sensitive.

On 2007-06-25, The Invisible Man > wrote:
>> On 2007-06-25, Zog The Undeniable > wrote:
>>
>>>> Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise
>>>> when accelerating gently at fairly low revs. Not a lot of
>>>> torque starting off on steep hills in Cornwall the last few
>>>> days.
>>>>
>>>> Garage can find nothing wrong. Never had any similar problems
>>>> with our 2005 1.8 but exhaust is quite white inside.
>>>>
>>>> Anyone come across anything similar? No problems over 2500
>>>> rpm. Goes best over 3500 rpm.
>>> You've answered your own question. Keep the revs up.
>>
>> So the 2007 engine is really that much worse than the 2005?
>>
> My mistake. The old MX5 was in fact a 2002 model.

Still people seem to be saying that the 2007 engine is just
plain un-drivable compared to a 2002. I find that a little
hard to believe.

> Our 2007 is difficult to drive in town centre traffic. It
> almost needs putting into 1st gear every time you turn at a
> green light at an intersection. I have driven a lot of cars
> over nearly 40 years but never had one this sensitive.

I haven't driven a 2007, but I'd be surprised if the NC engine
is that much worse than the NB.

--
Grant Edwards grante Yow! Hello. I know
at the divorce rate among
visi.com unmarried Catholic Alaskan
females!!

Grant Edwards wrote:
> On 2007-06-25, The Invisible Man > wrote:
>>> On 2007-06-25, Zog The Undeniable > wrote:
>>>
>>>>> Our 2007 MX-5 Coupé 2.0 (not sport) makes some knocking? noise
>>>>> when accelerating gently at fairly low revs. Not a lot of
>>>>> torque starting off on steep hills in Cornwall the last few
>>>>> days.
>>>>>
>>>>> Garage can find nothing wrong. Never had any similar problems
>>>>> with our 2005 1.8 but exhaust is quite white inside.
>>>>>
>>>>> Anyone come across anything similar? No problems over 2500
>>>>> rpm. Goes best over 3500 rpm.
>>>> You've answered your own question. Keep the revs up.
>>> So the 2007 engine is really that much worse than the 2005?
>>>
>> My mistake. The old MX5 was in fact a 2002 model.
>
> Still people seem to be saying that the 2007 engine is just
> plain un-drivable compared to a 2002. I find that a little
> hard to believe.
>
>> Our 2007 is difficult to drive in town centre traffic. It
>> almost needs putting into 1st gear every time you turn at a
>> green light at an intersection. I have driven a lot of cars
>> over nearly 40 years but never had one this sensitive.
>
> I haven't driven a 2007, but I'd be surprised if the NC engine
> is that much worse than the NB.
>
Which is why I posted here. I suspect ours has a problem

On 2007-06-25, The Invisible Man > wrote:

>>>>> You've answered your own question. Keep the revs up.
>>>>
>>>> So the 2007 engine is really that much worse than the 2005?
>>>>
>>> My mistake. The old MX5 was in fact a 2002 model.
>>
>> Still people seem to be saying that the 2007 engine is just
>> plain un-drivable compared to a 2002. I find that a little
>> hard to believe.
>>
>>> Our 2007 is difficult to drive in town centre traffic. It
>>> almost needs putting into 1st gear every time you turn at a
>>> green light at an intersection. I have driven a lot of cars
>>> over nearly 40 years but never had one this sensitive.
>>
>> I haven't driven a 2007, but I'd be surprised if the NC engine
>> is that much worse than the NB.
>
> Which is why I posted here. I suspect ours has a problem

If it was a couple years older I'd guess plug wires, but it
seems a bit soon for them to be shot.

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