spark plug issue

[Johnathansgalant]

alrighty ever since i got my car back from mitsu for my tbelt i heard a slight tick that sounded like my injector. I just bought injectors but i have not installed them or anything so i decided to change the plugs to make sure as that was the only thing left i could think of and last week my car started stuttering on wot. Any way, i pull out 3 plugs and they are normal - besides my oil tube seals - then i get to the last one nearest the battery. I pull it out and its missing the grounding over the electrode completely. Long story short, i replaced it with stocks cuz i could not find 7es on short notice. Now my engine is noise free and runs good but what do you guys think coulda caused that?? I dont think i have a bad bearing i dont hear anything and my knock sensor doesnt hear ne thing... thanks in advance

[diablos991]

How many miles were on your car when you replaced those plugs?

Maybe they were just worn out and old.

[WarmAndSCSI]

Detonation took out the plug ground strap. You could very well have a chipped piston as well from the same detonation event.

I've seen it at least a dozen times. Do a compression test, try to borrow a borescope, and if everything is fine, get a better tune (you're probably running too much timing advance).

You can also be using NGK BKR7E's which are readily available. Don't run 5 heat range plugs on a boosted engine.

[Johnathansgalant]

i think i had the plugs for 8 or 9 months - i was running bkr7e-11 but i had to get bkr5 to drive home.. im ordering the plugs today


I dunno i am running 9 degrees up top with 0 knock. This started when i got my car from mitsu... Would they have taken my plugs out to rotate the engine or something because it was perfect untill i did my tbelt.... thanks for the info i guess ill test her this weekend...

[WarmAndSCSI]

You shouldn't have to order anything. Almost every auto parts store has BKR7E's (4644) in stock.

And that's all fine and dandy, but detonation can still occur. I'm guessing you hadn't datalogged immediately prior to discovering this... Or that piston lost its ring land and part of a ring and damaged the spark plug on the way out. The stock cast crap pistons are not suitable for a sustained 14 PSI, no matter how good the tune is. Sorry, but I think you probably damaged that piston.

Spark plugs ground straps will not break on their own without significant detonation or a LOT of power. I've broken a few ground straps without any piston damage, but this engine has seen about twice the specific output of yours.

[Johnathansgalant]

ive been logging constantly with evo scan since i got the car back because i wanted to know if the issue was an injector or something else... Do i still have the logs is another story haha ... Although i agree i ran my car hard for few years so damage is more than likely im just confused... 2 maybe 3 counts on partial throttle but i never got knock on wot... but im probably in denial- its cool thanks for the info and for some reason nobody around here carries anything in 7 range dont know why - the last place ill check is probably bennet i think i even still have my 7eIX iridiums for now

[galantebeige]

Altough I am not as much of an expert I can say that when I did my timing belt I did remove the spark plugs for easier crank turning.
How about the small possibility that the Mitsubishi guys just installed a different spark plug than what you had? By mistake, you know......

[WarmAndSCSI]

Any AutoZone or CSK/OReilly hub store will have the BKR7E's in stock.

Knock detection is not infallible. Shit happens. The stock pistons will last only indefinitely with greater specific power output than stock... you've been boosted a while apparently, it would not surprise me. I've lost 2618 forged pistons on perfect AFR, low-knock tunes. And if you really are getting 0 counts of knock, are you sure your knock detection is even working? I've never seen a tune result in no detected knock. 1-2 counts is optimal and normal. Even the stock Evo X registers up to 8 counts bone stock.

You should look at the injector. Send them all off to get cleaned and flow matched or replace them all with new ones. None of us are going to know if the injector is bad. The most you can do is ohm it out without ghetto rigging an injector spray pattern test rig (which I have done before... :-\)

To the above post, no, I'm sure he pulled out a broken BKR7E or 7ES... which a dealership would just not accidentally have lying around. Nor would anybody be inept enough to put a broken spark plug back in an engine.

[Johnathansgalant]

u r right im looking at my logs in excel and i get the 1 to 3 knock counts it just doesnt show under my graph i forgot i have to hold the mouse to see the actual numbers or else it does averages... most i get is 3 count... i can see my knock voltage moving like normal also.. I just bought a compression tester so i will test away i will post results hopefully of a none blown motor -- or i may start a thread on my new engine build haha

[DFX]

is that one of those ticking noises that gets faster when the engine revs? i think i have a similar problem on mine.

[Johnathansgalant]

theres many ticks on these cars hahaha.. they probably all get faster with engine revs. But this on sounded like a bad spark plug wire or injector.. The normal tick is the lifter tick but its most pronounced at idle i would think

[WarmAndSCSI]

Blown pistons "tick" as well... once per RPM.

[DFX]

theres many ticks on these cars hahaha.. they probably all get faster with engine revs. But this on sounded like a bad spark plug wire or injector.. The normal tick is the lifter tick but its most pronounced at idle i would think

haha, yeah. i know its not the lifters because i got em fixed, but thanks.

[qnz]

Johns tick was loud. Sounded like we're riding with a machine gun. haha

[WarmAndSCSI]

Johns tick was loud. Sounded like we're riding with a machine gun. haha

A blown piston can sound just like an exhaust leak.... it just depends.

[Johnathansgalant]

what was the range for a normal compression test again?? Im gonna do it today and a quick search for me didnt do the trick..

[WarmAndSCSI]

what was the range for a normal compression test again?? Im gonna do it today and a quick search for me didnt do the trick..

Completely depends on your CR. I'd look for ~175-190 psi on a healthy non-turbo 4 banger.

[qnz]

Completely depends on your CR. I'd look for ~175-190 psi on a healthy non-turbo 4 banger.

hes right. I had 180-185 all across last time i checked

[Johnathansgalant]

ok thanks much guys i got the guage if u need it qnz haha

[qnz]

Johns computer is fried.

He has 210 psi all across. too much carbon buildup i guess

[diablos991]

Did he perform the compression test correctly with the engine warm and the throttle wide open?

[WarmAndSCSI]

Did he perform the compression test correctly with the engine warm and the throttle wide open?

Screwing up either of those things would cause lower cranking compression #'s...

[diablos991]

But it is still important to know if he did the test under the proper conditions.
It is always best to ensure accurate numbers before you move on to diagnosis.

[qnz]

i'll ask him, but even if he didnt have the throttle at WOT, he still has consistant numbers in all cylinders which is a good thing

[Johnathansgalant]

hmmm i did not crank the car so ill have to ask if he went wot. The car was definately warmed up but im not sure about the throttle. i got 210 205 208 210