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Steve
Steve, Technician
Category: Mazda
Satisfied Customers: 1065
Experience:  Garage owner for thirty years
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Can you please tell me what the spark plug gap should be on

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Can you please tell me what the spark plug gap should be on a 2019 184 bhp Mazda MX5 ND?
JA: Are you fixing your MX-5 yourself? What have you tried so far?
Customer: I was advised that my spark plug gap at 1.1mm was not standard and should be 0.8mm to cure a slight misfire. All the info I can get hold of states it should be 1.1mm.
JA: How many miles are on the car? Is it a steady misfire? Or random?
Customer: 7K miles. It is just a infrequent slight "fluffing" under various load conditions. My OBDII diagnostics presents the DTC code P0300.
JA: Is there anything else the Mechanic should know before I connect you? Rest assured that they'll be able to help you.
Customer: Yes, the car had had the BBR Super 220 conversion carried out.

Welcome to JA. My name is***** am a fully qualified vehicle technician with over thirty years in the trade. I will be happy to assist you today. Hopefully we can get this resolved quickly.
You will receive an offer of a phone call by the system, this only needs to be accepted if you wish to speak to me, I can otherwise continue to answer your questions via the thread.
The data I have for your engine suggests a gap of 1.1 - 1.4mm and I would suspect with iridium spark plugs that 0.8 would be too small a gap.

The code P0300 is a random multiple misfire and may be due to the plug gap but I would say that the 1.1mm gap is the norm in your engine.

I hope this answers your question but I want you to be 100% happy with the answer so do please feel free to ask any further details by replying to this thread.
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Steve

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Customer: replied 11 days ago.
Hi Steve. The tuners changed the spark plug gap to 0.8mm after I had reported the misfire. They insisted that the gap should have been 0.8mm from new and not 1.1mm. After their conversion I had had a previous fault code P0087 (Low Fuel Rail Pressure) which also put the engine into limp mode. The misfiring code happened after this. I felt that reducing the spark plug gap was just a "sticking plaster" remedy and it was not addressing the root cause of the problems. I have recently replaced the spark plugs with new ones set at 1.1 mm. I have not yet had any misfire issues. Could the misfire be related to the Low Fuel Rail pressure event?

Nice to talk.

As confirmed the gap of the NGK Spark Plug ILKAR7L11 fitted to your Mazda MX5 should be 1.1mm with a tolerance up to 1.4 mm

Steve

It was a pleasure to assist you today. If you have any follow up questions then please let me know. I will reply as soon as I can to help with any further queries.
Steve