Piston hitting plug?
Thread Starter
Newbie
Joined: Jan 2018
Posts: 61
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From: Las Vegas, NV
Thread Starter
Newbie
Joined: Jan 2018
Posts: 61
Likes: 6
From: Las Vegas, NV
My logic is, if it is higher up, and it is because middle of pistons are dirty, they will not be able to make contact if higher up. Spark plugs regapped, new washers on, installed, started..running fine....but for how long.
I agree with barneyb that it is more likely detonation bent your plugs than 8mm of cabon buildup on your pistons. 8 mm of buildup is a serious massive gunk that will throw off your engine balance. Lol
Starting with simple first: Do you drop the plugs into the head when you install them? If they bump the head on the way down, that could close the gap. I've seen it happen, so I always lower them down in a spark plug socket.
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Joined: Jun 2006
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From: Grand Island, NE
What about being tuned on 93, and driving on 91 as no 93 in Vegas? I get some DEEP backfires at times while decelerating at times. Injectors are factory, non upgraded at all.
Just did the magnet test, nothing in there. But, it gave me a chance to really feel the pistons, and they are very carbon, feels like asphalt in there, atleast number 1 and 4, the others are smoother, but still like sand paper. This is soo odd haha. I am very fast at pulling the plugs though now, so that is a plus. I am not worried that I bend the gap back and forth so much it is gonna break off eventually. Pulling the whole head really does not look too hard on this car, but currently my only car, so it would be a pain finding time to do it.
Just did the magnet test, nothing in there. But, it gave me a chance to really feel the pistons, and they are very carbon, feels like asphalt in there, atleast number 1 and 4, the others are smoother, but still like sand paper. This is soo odd haha. I am very fast at pulling the plugs though now, so that is a plus. I am not worried that I bend the gap back and forth so much it is gonna break off eventually. Pulling the whole head really does not look too hard on this car, but currently my only car, so it would be a pain finding time to do it.
Your engine may be in a danger close situation. Gasoline is supposed to burn in an engine. If it explodes, the shock can break things and bend the electrode on the spark plug. What it breaks is usually the piston. The wrong octane, heat, and a cylinder pumping oil are causes of detonation. The main cause is a lean mixture. That is why I suggested a fuel injector problem.
A good shop will have the ability to flow test the injectors.
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Joined: Jan 2018
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From: Las Vegas, NV
No, I am rather careful, but, lets say I did drop them, and it caused the bend in gap, Why would it run fine for hour/days/week before it starting to misfire and have an issue?
Thread Starter
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Joined: Jan 2018
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From: Las Vegas, NV
I asked the local tuner about it, (the 91/93 thing) and he said I do need to get tuned, but that difference is not a big deal, just dont do super long like 3rd gear pulls etc. The car is new, so I tend to get on it every now and then, but just crusing, under 3500 rpm may cause this? I am not doubting, just asking.
Update, added double washers to all the plugs, ran like total crap, took the washers off 2 and 3, as they never had a problem, and it is running best it ever has. Very strange. Been only 2 days, but so far so good. I agree makes no sense, but it is working. I have all teh teals I need to adjust the gap with me at all times now, will keep you posted.
Update, added double washers to all the plugs, ran like total crap, took the washers off 2 and 3, as they never had a problem, and it is running best it ever has. Very strange. Been only 2 days, but so far so good. I agree makes no sense, but it is working. I have all teh teals I need to adjust the gap with me at all times now, will keep you posted.
So double washers probably pull spark plug tip completely out of combustion chamber. 
It's possible that under light throttle, timing is too advanced for 91. Try good quality octane booster until you get retuned for 91. The difference in WOT maps may not be much but light throttle runs fuel hotter for economy and that could be significant in timing.
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It's possible that under light throttle, timing is too advanced for 91. Try good quality octane booster until you get retuned for 91. The difference in WOT maps may not be much but light throttle runs fuel hotter for economy and that could be significant in timing.
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I asked the local tuner about it, (the 91/93 thing) and he said I do need to get tuned, but that difference is not a big deal, just dont do super long like 3rd gear pulls etc. The car is new, so I tend to get on it every now and then, but just crusing, under 3500 rpm may cause this? I am not doubting, just asking.
Update, added double washers to all the plugs, ran like total crap, took the washers off 2 and 3, as they never had a problem, and it is running best it ever has. Very strange. Been only 2 days, but so far so good. I agree makes no sense, but it is working. I have all teh teals I need to adjust the gap with me at all times now, will keep you posted.
Update, added double washers to all the plugs, ran like total crap, took the washers off 2 and 3, as they never had a problem, and it is running best it ever has. Very strange. Been only 2 days, but so far so good. I agree makes no sense, but it is working. I have all teh teals I need to adjust the gap with me at all times now, will keep you posted.
As for the tune, staying in closed loop should be fine. Just don't give it much gas or rev it much and get it tuned asap.
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Joined: Jan 2018
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From: Las Vegas, NV
Actually, that wouldn't make sense. I missed that part of your post, sorry. I was hoping it would be something easy LOL.
The fact that the washers helped is a definite warning sign. You really need to figure out what's going on, as you already know. All four plugs are the same? This is just weird.
As for the tune, staying in closed loop should be fine. Just don't give it much gas or rev it much and get it tuned asap.
The fact that the washers helped is a definite warning sign. You really need to figure out what's going on, as you already know. All four plugs are the same? This is just weird.
As for the tune, staying in closed loop should be fine. Just don't give it much gas or rev it much and get it tuned asap.