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Discussion Starter #1
just passing on some info. thanks to rocconi for putting me on the right track, i think its the damn plugs after all.

all this is my theories and will be proven yet either right or wrong...time will tell.

SHORT STORY: gap your plugs for 0.035" instead of the recommended 0.044".

LONG STORY:
ok so i was having the common missfire from my accent (1.6L) as many of you have had. often the coilpacks get blamed. i no longer think this is correct. its my belief that the recommended spark plug gap of 0.044" is incorrect for our coils.

so at first i used the NGK V-Power plugs (v cut electrode) gapped to 0.045" - i have a wire gapping tool so 0.044 isn't an option. worked fine for a few months then the dreaded misfires began. i assumed coils but all testing showed them to be in perfect health. same with the wires....

rocconi mentioned to me in another thread that he had used NGK Iridium plugs and gapped them a little tighter than the 0.044". this seemed to solve the problem for him. this got me thinking...no way in hell does a piddly little 1.6L engine require a high end spark plug like the iridiums. not saying its a bad idea, i just feel its unnecessary. if you want them for performance or other reasons, thats different.

from what i understand simply plopping in iridium plugs will reduce the needed voltage to create your spark by approximately 5000V. this is due to the fact that iridium is an excellent conductor close to that of copper and the ability to make an insanely small tip on the plug due to the hardness properties of iridium. simply put, you get a bigger spark with the same gap compared to copper.

this brings me to think that the problem is not the coils, wires or plugs - its the plug gap. smaller plug means less voltage required for the electricity to arc over that gap.

to further confirm this all my old plugs (used about a year only, same ones) have a good coating of soot indicating that i'm either running rich (not likely in an unmodified car with no error codes from the ECU) or the mixture is not being burned entirely. that would be my misfire. upon inspection my plugs had a gap of closer to 0.050". thats slightly out of spec but not by much here. OEM equipment SHOULD be able to create a spark with this. that then leads me to believe that the OEM coils are rather weak and hyundai is really pushing it with that 0.044" spec on the plugs.

the coils simply do not push out enough voltage for the specified plug gap.

end of the story is new plugs with a tighter gap - i used 0.035". the results are a MUCH more responsive throttle and no misfires! YAY!

within the next couple weeks or even months i'll keep an eye on my plugs for any soot deposits. if they are pretty much gone, then i think i've got the problem solved. i'll post here with my findings. i put a lot of miles on my accent so i think i should know sooner than later.

also i intend to check plug gaps every 6 months now as opposed to checking every year.

just my take on this seemingly common problem, feel free to think i'm full of ****. thats a possibility anyways.
 

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i had the same issues, and went to bosche pre-gapped.

what ever the most expensive ones where.

that and new wires.
 

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when i had the issue, hyundai could never replicate it. it sucked. so i had to leave the car there. then drive there in the morning to show them how to do it.

they still could never figure it out. i replaced wires and plus and boom!

worked amazing
 

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My wifes 2005 1.6L accent at 60,000Kms from new & dealer serviced, has just gone out of warranty and has started not so much misfiring but not picking up smoothly and the more gas I give it the worse it gets, no CEL light though.
2 new lots of plugs, Bosche & NGK, new plug leads and the problem seemed to be worse. I re gapped the plugs from 1mm down to .8 mm and it worked much better but still their.I checked the spark to new plug gapped at 1mm and the spark was very weak, it was thin and jumping around on the electrode, this happened from both coilpacks. I finally lowered the gap to a small .6mm as a test and although it was down on power a smidge it did not hesitate or misfire at all.
Question, is there any component that can effect spark on both coilpacks or is it likely both coilpacks are failing in a similar way at the same time ?
The car is left unshaded at my wifes work car park and the temperature on the bonnet will fry an egg most days in the summer months so this could cause coilpacks to fail.
Any thoughts ?
 

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If I wasn't so dam cheap I would throw a MSD ignition system on my Accent and increase the gap to around .060. I really think that the stock coil packs are not up to the job. I was also thinking of using one coil per cylinder and building a FET amplifier to interface the new coil pack to the ECU but I never got around to it.
 
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BTW, since I went to the small center electrode NKG (BKR5EGP) plugs with a .035 gap my misfire problem has not come back. I think that they are platinum and they cost under $5 each.
 

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Discussion Starter #10
its more the gap than anything. although the platinum allows a smaller tip, the electrical resistance is higher than copper so there really isn't much benefit. iridium on the other hand...thats a different story. but then the cost isn't worth it.

btw, for anyone thinking it it's not a good idea to gap platinum or iridium plugs out of the package and especially not later. two reasons: 1. you can contaminate the electrode with your gapping tool. 2. its smaller, and easier to brake off.
 

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Zero the resistance of the tip is negligible in comparison to the resistance of the ignition wires and the resistor inside some plugs. The resistance is there to reduce radio interference and lengthen the duration of the spark. Also, since one only bends the bigger steel ground electrode I don't see how bending it within reason can damage the plug. I have never used an iridium plug so I do not know how they are constructed.
 

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Discussion Starter #12
yes very true that the wires, etc are much higher resistance. thats why i don't buy into expensive plugs. granted, plantinums aren't that bad.

its iridium that the breaking of the tip is more of an issue as the hardness of the material is much higher and therefore much more brittle. that coupled with the fact that the electrode tip is so small makes it easy to break if you fiddle with it too much.

as for platinums, breakage isn't so much the issue as contaminating the platinum. most of these gapping tools contain lead and other heavy metals. that can get impregnated into the platinum from when you're gapping them. remember, platinum is somewhat chemically reactive - thats why its used in catalytic converters.
 

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In the 60s, before all of this fancy electronic ignition stuff, the engines all ran plugs gapped at between .020 and .030. If you were running a lot of revs and high compression .020 was the ticket. Large gaps give you a little better firing of lean mixtures but you need enough voltage to use them. Otherwise they are counter productive. Do you think that there is a market for a 4 coil setup for Hyundais?
 

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Discussion Starter #14
In the 60s, before all of this fancy electronic ignition stuff, the engines all ran plugs gapped at between .020 and .030. If you were running a lot of revs and high compression .020 was the ticket. Large gaps give you a little better firing of lean mixtures but you need enough voltage to use them. Otherwise they are counter productive. Do you think that there is a market for a 4 coil setup for Hyundais?
hmmm good question. i thought about how to adapt some MSD performance ignition coils to an accent, but its just not worth it. all they really need is a coilpack that is better sealed with more windings one the output coil. would be nice not to worry about the bloody gap!
 

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Back to my wifes accent weak spark problem & some interesting
(Baffling) observations.
I replaced the coil pack, and it is still the same weak spark that misses and loses power above 2K revs when plugs gapped to 1mm, takes about 30 seconds go get to 60KPH.
I wandered about the engine to body earth possibly being High Resistance but instead of getting my meter out I just ran the engine on 3 cylinders & took No1 lead through a spare 1mm gapped plug & earthed it to the battery ground terminal.
The spark remained the same weak thready thing that danced around the post BUT as I moved the plug away from the battery ground post the plug body arced across to the post for a distance of about 1.5 inches, the arc was strong, white & consistent, but the plug spark remained its thready self, no change at all. Hubba Bubba what is going on here. I tried the same test without a plug in the wire and a bright spark jumped from the end of the wire almost 2 inches to ground. Has Hyundai changed the laws of physics without telling me ?
To give that plug body to ground arc means that there is plenty of power in the coil packs, stacks of it in fact but why is that not showing as a strong spark at the plug. Bosche or NGK behaved the same. A previous post mentioned thin electrode NGK plugs fixed his problem, I may pick up a set of those as a thin electrode would concentrate the spark and stop it dancing around so much. Anybody any thoughts on this problem ?
 

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The only other thing that could be happening is a plug that is shorted to ground. Perhaps there is some sort of path for the spark to travel to ground other than the center electrode. Try a new plug. If you get the same result then that is just the way the spark should look. BTW, in theory, it can hurt the ECM if you let the spark jump 2 inches. The voltage in the primary winding of the coil pack will get too high and damage the drive circuitry.
 

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So is the voltage or current to the primary winding of the coil variable, if so then that is probably the reason for the weak spark ?
Also several different new plugs were used so it is unlikely that they are all defective.
On the equipment I service (photocopiers) we use high voltage to get a controlled charge on the surface of the drum and that charge is monitored and adjusted as required by discreetly measuring the current flow in the circuit.
Could the ECU be doing a similar thing but accepting a less than optimal current flow and therefore weak spark ?
 

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I too had misfires on cylinder one. My biggest mistake was buying a new coil. ITS NOT THE COILS PEOPLE! Mess with the spark plugs before u buy the 80 dollar coil. i read here to gap them at .35, after doing so the misfires where less severe, but still frequent. i decided to try to gap them smaller at .32, engine light turned off immediately and misfires have been gone since. I used the manufacturer spark plugs, 8 dollars each. Hyundai is a crap company with crap service. They tell you the spark plugs are suppose to be gapped at .44 to make a buck off you, so when it misfires you can take it in for work, and they can charge u for all kinds of services you dont need! Plus charge you for labor too. I wish i where to have read this before i invested 200 dollars trying to fix a 40 dollar problem. If you read this, your welcome.
 

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Hey ,

Thank you so much for this info, been having all the same issues, codes had me thinkin it was three different sensors. Checked on google before i started spending money on sensors and came upon this thread. Just re-gapped to ..035" and waa-laa, seems to be running perfectly.

And also, a bit of advice for people with similar models to 2001 Sonata, if youi are doing any removing of electrical/igniton parts such as coils, there is a little trick to reset the cpu and it has worked for me several times when car is stalling for no apparent reason.

1.) Remove Negative Battery Cable
2.) Push down on brakes 5 times down and back up, on the 5th push, hold for 5 seconds
3.) Re connect Negative Battery Cable

This should perform a reset on your ECM i believe its called, or the brain.

They may remove this post because of this valuable little secret, but if you have this as a backup, you wont be sorry
 

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U know what man? It still missfired... i ended up taking it to hyundai and they fixed it becuz of warranty. They said it was a connector... that the prongs on the connector where crooked and fell out of place so they werent receiving strong signals causing the missfires. How ever i think they where just feeding me b.s. so im still not sure what they did exactly. They did give my computer an update. The problems have stopped since, but hyundai fixed it, so i couldn't pin point exactly what it was. Sorry. On another note i wasnt happy w hyundai of el paso. They weren't very helpful, and wanted to give me the run around so they could make a buck off me. I had to talk to 3 different managers n threaten to file a "lemon law" clame.
 
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