tom13
Part of things
Posts: 571
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Apr 22, 2017 15:12:44 GMT
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Hey guys, Trying to help out a friwnd and fellow mx5 owner. His 5 is running a bit rough a lower revs. Almost like a miss. Its a bit hesitant when you pull away but clears fine when you rev it a bit. One thing i did note was that if you hold it at a certain rpm say 3000 its clear but then start to come back in again. We changed plugs and leads. Checked location of leads and they are correct. Checked air filter was in good condition and not blocked. Cooling system seems to be working fine temp guage is normal. I have attached a picture of the plugs which look white on the tips. I'm assuming its running hot or or not getting enough fuel? What else can we so to check it over. Cheers for any help. Tom  |
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Apr 22, 2017 15:16:55 GMT
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Plug #4 looks wet can you check the resistance of the insulation? Below 10 Ohms and it's dead. The other 3 look fine to me.
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tom13
Part of things
Posts: 571
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Apr 22, 2017 15:30:08 GMT
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Plug 4 was dry actually just blackened? Are they supposed to be a bit white on the tips? Cant check the insulation at the moment either.
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tom13
Part of things
Posts: 571
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Apr 22, 2017 15:31:40 GMT
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Shoukd say those are the old plugs. New ones and leads have been put in and it is still the same.
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Apr 22, 2017 15:37:02 GMT
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Light grey is fine, deposits and pitting are bad though even if it's the right colour. Is the MAF known to be good? And the temp sender?
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Last Edit: Apr 22, 2017 15:37:17 GMT by xbl
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tom13
Part of things
Posts: 571
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Apr 22, 2017 15:43:19 GMT
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Dotn know about maf. We never tried it. We did disconnect the air intake before the maf and it ran the same.
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Apr 22, 2017 15:43:58 GMT
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Try unplugging it, it will drop to a default fuel map - it will pop the EML on though.
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tom13
Part of things
Posts: 571
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Apr 22, 2017 16:05:24 GMT
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We did do the acutally. I forgot sorry. It has a plastic connection on the back doesn't it?
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tom13
Part of things
Posts: 571
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Apr 22, 2017 16:06:00 GMT
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How can we check fueling?
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Apr 22, 2017 16:08:29 GMT
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Emissions test or a wideband lambda sensor.
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Apr 22, 2017 17:30:49 GMT
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Looks like a single cylinder issue with only the one plug discoloured.
Is it a dizzy or coil pack ignition?
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Needs a bigger hammer mate.......
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tom13
Part of things
Posts: 571
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Apr 22, 2017 17:49:33 GMT
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Its a coil pack.
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Apr 22, 2017 17:52:13 GMT
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Hate to say it but it may well be the coil pack.
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,712
Club RR Member Number: 34
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Apr 22, 2017 21:33:35 GMT
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As said, coil pack or lead to plug 4. Only other thing it could possibly be is the head gasket going.
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Last Edit: Apr 22, 2017 21:34:51 GMT by Dez
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tom13
Part of things
Posts: 571
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Cheers guys we will change the coil pack and see from there.
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ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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Apr 23, 2017 19:19:26 GMT
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What plug leads do you have?
Have you checked for any codes? While it can't tell you much the code reader is less than £1. It's basically a 12V LED and a bit of wire.
To me it looks like a CTS sensor issue or a lamdba. Then again it would default to a failsafe map with an iffy one potentially.
Plug 4 could also be wetter due to the compromised cooling path of the MX-5 ; the engine was originally designed for the 323.
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Last Edit: Apr 23, 2017 19:24:44 GMT by ChasR
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