Missing, coughing and sputtering

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Stevo
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Missing, coughing and sputtering

Post by Stevo » Sat Nov 14, 2009 10:15 am

:cry: I took my NB 98 1600cc down to the "Naki" and back on Thursday and on the way back, it started running rough at idle and missing under acceleration. It ran fine at speed though.
I have just removed the plugs and they are fine and appear gapped properly (does anyone have the correct gap). I would suspect the plug leads but that is unlikely, it has handmade "Nology" plug leads (see photo in garage section). http://www.mx5forum.co.nz/garage.php?mo ... cle&CID=44
I couldnt even find the fuel filter.
So home mechanics, what should I start looking at?
Failing that, can anyone recommend a good MX5 garage in Tauranga as I need it running properly for our club run next Sunday.
98 NB Evolution Orange

WideOpenThrottle
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Post by WideOpenThrottle » Sat Nov 14, 2009 12:19 pm

Things i might look at-moisture in/around the plugs & electrics
Dirty airflow meter sensor-spray clean with CRC air flow meter cleaner from Repco
Dirty fuel & filter or with air leaks
Blocked fuel jet in the throttle body housing
Vacuum hose leaky or popped off
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Habanero666
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Post by Habanero666 » Sat Nov 14, 2009 5:25 pm

Blocked fuel jet?
Tires aren't cheap!

Euen
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Post by Euen » Sat Nov 14, 2009 6:08 pm

Fuel filter is located under a cover, under the floor, just in front of the right rear wheel.
TG Sports, classic roadster - modern technology. NA1800, 99 head, 11:1 +2mm Wiseco pistons, Link LEM, Alloy f/wheel, JR headers.

Stevo
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Post by Stevo » Sat Nov 14, 2009 8:09 pm

Thanks. Slowly working my way through it. Cheers Stevo
98 NB Evolution Orange

Grant
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Missing, coughing and sputtering

Post by Grant » Sat Nov 14, 2009 8:17 pm

After seeing varous reviews and reading about the Nology leads, I would go
and borrow a set of ordinary leads from another car and try those. I put
them in the same catagory as Monster HDMI cables at $400.00 each when the
$20.00 ones are just as good!
My NA1600 had trhose symptoms not long after I bought it with 130,000km on
the clock. I installed a set of standard leads in it and they were still
performing without a problem when I sold the car with 220,000km on it.

Grant.
Red 2006 NC Tiptronic
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WideOpenThrottle
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Post by WideOpenThrottle » Sat Nov 14, 2009 8:56 pm

sorry Hab-poor choice of words somehow not what i meant to say-more like the throttle body can get gummed up and there could be an adjustment screw{not fuel jet, maybe air jet thingy]that may gumm up as did on our NB.
I stand corrected!
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Stevo
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Post by Stevo » Sat Nov 21, 2009 4:49 pm

:D Problem solved. It was the plug leads after all. 2 of them had small holes blown in the tube part that goes down through the tappet cover. Many cars use this type of plug lead and they are all prone to burning through in this area.
Sadly I had to replace all 4 leads ($116 worth) as I couldnt just replace 2 Nology with standard since they are not compatible, as the Nology's have built in capacitors.
Anyway, its great to have it running on song again.
Cheers Stevo
98 NB Evolution Orange

poison
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Missing, coughing and sputtering

Post by poison » Sat Nov 21, 2009 4:59 pm

That's good news Stevo. I remember having some cheap leads on an old Cortina
(anyone remember those..lol) lifting the bonnet at night was like a
fireworks show from all the electrical leaks. After many breakdowns, usually
when taking someone on a first date...grrr... I'll certainly never miss
owner a car with mechanical advance and points. Young guys today have no
idea how lucky they are with the general reliability of EFI.
:twisted: Gazda in the white HOT Mazda :twisted:

Mark
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Post by Mark » Sat Nov 21, 2009 7:14 pm

Stevo wrote:Many cars use this type of plug lead and they are all prone to burning through in this area.
Yep I had a Mazda 323 GTx turbo (in Laser TX3 4wd clothes) back in the early 90s. At that time nobody seemed to know this was going to be a problem, so I had all sorts of problems getting it diagnosed, you can't see the arcing through the covers even in the dark. Mazda were charging over $300 for the leads, Ford a little less for the same thing, but better NGK leads cost me about $75.

Hojo
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Post by Hojo » Tue Dec 15, 2009 3:01 pm

I just had this same problem! I just (30 mins ago) replaced all of the spark plugs (they weren't looking to good anyway) but the problems reamins... I guess I will have to shell out for some new leads aswell....

Timmo
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Post by Timmo » Tue Dec 15, 2009 3:36 pm

I replaced leads, plugs, airfilter, oil and oil filter and fuel filter a couple of weekends.....car goes much better now! It used to have a hesitation/torque hole until 5000 rpm whereas now I can happily drive/accelerate under that.

(part of that was replacing the stock airbox and fabricating and cold airbox and heatsheild over a pod filter too but definitely noticeable)

DBM58
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Missing, coughing and sputtering

Post by DBM58 » Tue Dec 15, 2009 4:33 pm

Hojo wrote:I just had this same problem! I just (30 mins ago) replaced all of the spark plugs (they weren't looking too good anyway) but the problems remains. I guess I will have to shell out for some new leads as well....
I have a set of leads that you can borrow to try and diagnose the problem. I am in Royal Oak, Auckland.
David

Stevo
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Post by Stevo » Wed Dec 16, 2009 5:14 am

Hojo wrote:I just had this same problem! I just (30 mins ago) replaced all of the spark plugs (they weren't looking to good anyway) but the problems reamins... I guess I will have to shell out for some new leads aswell....
I checked all of the usual stuff (the plug gaps were a bit small, which can contribute to lead burn through) but couldnt see any problems when inspecting the leads.
I took it to a garage who could put it on their diagnostic computer and it was found that 2 leads were arc-ing out.
Plug leads cost $116+ courier and labour was 1.25 hrs at $69/hr all including gst. (roadtested, and checked on all sorts of other stuff as well.)
The burn through marks on the leads were so small, they were only just visible.
Sometimes its quicker and cheaper to get it professionally looked at rather than DIY through trial and error.
Cheers Stevo :wink:
98 NB Evolution Orange

Habanero666
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Post by Habanero666 » Wed Dec 16, 2009 9:29 am

Good work, and a very fair retail price!

I think the diagnostics are the crucial part aswell, otherwise you are paying someone to replace parts untill the problem goes away. Any monkey could do that, and it is expensive
That is why it is possible for workshops to charge for diagnosis, test equipment etc... It is really about finding that professional, well trained Technician.

So good result there.

Happy zoom zooming :D
Tires aren't cheap!

Ian
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Post by Ian » Wed Dec 16, 2009 6:23 pm

While there will always be exceptions, one of the few weaknesses of an MX5 is the propensity (if that is the right word) to require replacement plug leads every 50,000k, esp if using factory/cheapish leads. This is well documented, and was explained to me when I first bought my car, by a fellow enthusiast. Had a plus lead go out on me on a long trip...symptoms just as had been described to me, solution with a new set - instantaneous.
If I bought another MX5, it would be the first thing I would change along with the fuel filter (which many owners ignore).

Ian
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Hojo
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Post by Hojo » Thu Dec 24, 2009 11:50 am

Just got new leads from Ross at mx5mart. They are working brilliantly, it seems that this is the go-to fix if your car is running on 3 cylinders (or less).

jethro25
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mx5 misfire

Post by jethro25 » Mon Dec 28, 2009 3:07 pm

Just about every jap cars missing problem now days is due to the spark burning through the plastic plug "stalk" to earth. In the old days worn out plugs just stopped sparking, but now the massive electronic ign spark will find somewhere to go! Change ya worn out plugs sooner, and this won't happen. Fixed dozens of em......
the universe is always in balance.

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