Cylinder One Spark Plug Fouling - Oil on Plug Thread - Slow Start

[conrad51]

Just wanting to get a second opinion.

Car: 2012, 43000 miles. NGK one step colder, corksport intake, Autotech HPFP, PD Tune.

Been having a little trouble with starting as of late with hard starting, or slow start, what ever you want to call it. When trying to start cold or hot the car can take 5-10 seconds to start. Been working through a checklist trying to find the culprit when i think I've found it. When i changed the plugs at 34,000 miles i noticed cylinder 1 plug was black out compared to the rest, thinking this was just the stock tune running rich i didn't think anything of it, however it continues to plague me now.

Now when i pulled cylinder one plug recently i noticed on the thread a reasonable amount of oil, not enough to say it was coated in oil, but enough to know it shouldn't be that way. The other plugs had no signs of oil on them at all. The plug end itself was completly blacked out. This seems to be my issue for the hard starting, for when i spray the fouled plug in engine start (semi cleaning it) the car will start fine for 200 odd miles but slowly gets worse.

Am i right in thinking that excess oil is entering the cylinder, most likely valve cover gasket? Or could it be injector seals? Or something else?

The only other issue i can think of occurring is in traffic, at low speeds i.e. 10-20 mph, when applying a small amount of throttle, enough to accelerate rather than coast, it stutters a bit and then goes away. All other speeds its fine, no problems at wot or anything, just at those low speeds when i guess the engine is nice and warm from sitting in traffic.

Any opinions are greatly appreciated.

Thanks

[anavrinIV]

First off, you need stock heat range plugs...the step colder plugs are affecting your car negatively.

Second, injector seals won't cause this but a broken piston, bad rings, bad valve guides can. You need to do compression and leakdown tests first and foremost. Actually second...first you need the proper plugs.

[conrad51]

Is this going to affect my tune? I ask Will, who did my tune, and he said just to stick with the one step colder. I do have a brand new set of stock heat range plugs to put in however, because this issue was present on the standard plugs, how can you think its the heat range? I ask out of curiosity because i agree with you on that part, i think these plugs do not suit my car and my driving style, they are all a little to black for my liking.

Thanks for your help, going to do a compression test this weekend however will have to read about a leak down test as i carn't say i have ever heard of it. Makes sense though.

Originally Posted by anavrinIV First off, you need stock heat range plugs...the step colder plugs are affecting your car negatively. Second, injector seals won't cause this but a broken piston, bad rings, bad valve guides can. You need to do compression and leakdown tests first and foremost. Actually second...first you need the proper plugs.

[anavrinIV]

Originally Posted by conrad51 Is this going to affect my tune? I ask Will, who did my tune, and he said just to stick with the one step colder. I do have a brand new set of stock heat range plugs to put in however, because this issue was present on the standard plugs, how can you think its the heat range? I ask out of curiosity because i agree with you on that part, i think these plugs do not suit my car and my driving style, they are all a little to black for my liking. Thanks for your help, going to do a compression test this weekend however will have to read about a leak down test as i carn't say i have ever heard of it. Makes sense though.

I don't think the plugs are causing the oil issue but they aren't helping with your stumbling. Colder plugs are used when detonation due to cylinder heat is a concern or an issue (high RPM, lots of airflow, high boost) but are less efficient and can create drivability issues like you're seeing. Your tune shouldn't need any adjustment to run the warmer plugs.

[Shwaykid]

Same thing happened on my 200SX SER. It was the valve cover gasket. The rubber seals that seal around the plug holes were hard as a rock and crumbling.

[conrad51]

So turns out it wasn't oil on spark plugs but un-burnt fuel. Compression and leak down test was all ok, all the cylinders are within 5-10 psi of each other.

Diagnosis at this stage is probably bad injector spray pattern and causing fuel to 'dribble' into the cylinder, causing excess fuel entering the combustion camber and fouling the spark plugs. Is there any way to measure this? I know on diesels some injectors have a valve at the end to allow this fuel to 'dribble; into the cylinder and this can be measured by the ecu, can this be done on the mazda?

[dp3]

You possibly have a carboned up EGR valve. I had the same symptoms on my 2010 MS3 and my 2013 MS3. Take it off and inspect it. Valve is likely sticking. Pretty common issue. Soak it overnight in carb cleaner, scrub off the deposits and re install. This thread discusses it a bit. Carbon build-up on Speed 6/3 & CX-7. A big issue!!!

[conrad51]

Already been done as i thought the same as you however it changed nothing. There was a little bit of wear on the inside of the valve but nothing major. Cleaned it all up, cleaned the pipe and put it back on.

[anavrinIV]

you could have a leaking injector, it happens. May be time to get a new one or, if you can afford the down time, send yours out to be cleaned and checked.