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2013 Hyundai Elantra - Misfiring and bad idling


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J.cogitation
User

Nov 23, 2020, 9:52 PM

Post #1 of 20 (329 views)
2013 Hyundai Elantra - Misfiring and bad idling Sign In

2013 Hyundai Elantra Limited, with 164k miles, 1.8 L 4-cyl engine.

I was told by the previous car owner that it was misfiring, and needed replacement spark plugs. Without really checking, I got four new plugs. I pulled out the old plugs, and they were all iridium. All looked fine except 1 which was covered in black carbon build-up. I replaced them anyway.

10 miles later, the car is misfiring again, especially near idle. Especially as the car warms up or idles a while.

It will idle at 900 on cold-start, down to 750rpms, then once it warms up more, start dropping as low as 400rpms, up to 1100 and down and up again, repeatedly, while misfiring. Also misfires (putt-putt effect) from around 750rpms up to ~2,000 rpms until it gets above 2,000 and then seems to smooth out.

The engine seems to shake and the car vibrates pretty strongly, but it comes and goes and doesn't always vibrate.

A final possible factor: The car was sitting for around 6 to 8 weeks, until the owner sold it to me. It had 4 gallons of old gas in it. I filled it with 8 more gallons of new gas.

I have also recently replaced oil with 5W20 synthetic, and done a brake job on all four tires.

Hope this isn't too much information. Thanks in advance for any help. :)


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 23, 2020, 10:52 PM

Post #2 of 20 (320 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

The cylinder that was carbon fouled isn't firing the build up is unburned fuel no doubt. Of course it's running like crap on 3 of 4 cylinders worked for 10 miles and did it again.


Too late now but should have quit then for any other items to find out why. It's wide open to lacking proper spark or excessive fuel delivery washing cylinder wall perhaps but would do a compression test anyway.


Do the little squirt of oil too see if it's even close to the others then?


That's job 1 now and was when you acquired it maybe a disaster so get on it ASAP it's possibly too late for damage to converter and O2 sensors?
Other: 8 week old fuel should be fine I wouldn't waste time blaming that if you believe that. Also, use OE spec plugs not whatever came out or you used if not exactly what it calls for there are not tricks in plugs that really do anything better than OE spec ones,


T



(This post was edited by Tom Greenleaf on Nov 23, 2020, 10:57 PM)


J.cogitation
User

Nov 24, 2020, 12:37 AM

Post #3 of 20 (311 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

Appreciate the quick reply, Tom.

Can I borrow a compression test kit from a car shop, hopefully?

What is a "converter"?

Understood about the fuel. Thanks.

Concerning spark plugs, I had already bought 4 of these and installed them before posting: https://www.walmart.com/ip/Autolite-Iridium-Iridium-XP-Spark-Plug/165130904?wmlspartner=wlpa

I have the 3 still perfectly good plugs I replaced, which were another brand of iridium plugs. I was going to use one of those to replace the one I just put in the bad cylinder. Terrible idea?

Hopefully not a disaster. I can stop driving it until fixed.

(This post was edited by J.cogitation on Nov 24, 2020, 3:03 AM)


Tom Greenleaf
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Nov 24, 2020, 4:46 AM

Post #4 of 20 (298 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

"Compression tester:" Ask if a parts outlet rents them out, some free with full deposits. Then learn how to use it.


"Converter:" Was just saying catalytic converters(s) don't do well or can die if over worked so running on 3 of 4 cylinders is wrecking it. It's quite possible it's flashing an engine icon now on dash means to shut down ASAP or you are causing damage. Hope that warning exists and hasn't been defeated to sell this thing.


OE or OEM = Original Equipment or sometime "M" the manufacturer of the parts it was made new with. Other than those suggested by a car maker or equal to that can be the problem not cure it - that's all but important.


Back to the plugs. You can take out the fouled one, just warm it up a bit and swap it with another see if the other fails or problem moves with that plug. That's just "swaptronics" with what you have it's possible to get a bad one but doubt it you were advised pre-purchase that it needed plugs and probably was known some disaster lurked but can't know that for sure yet,


Tom



(This post was edited by Tom Greenleaf on Nov 24, 2020, 4:47 AM)


Hammer Time
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Nov 24, 2020, 4:53 AM

Post #5 of 20 (291 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

Autolite plugs in a Hyundai? Not a good combination at all.

You should be using NGK in a Hyundai. The brand DOES matter but you need to get to the bottom of your issue first before changing them.

The seller lied to you about the problem being just spark plugs.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 24, 2020, 4:53 AM)


J.cogitation
User

Nov 24, 2020, 2:37 PM

Post #6 of 20 (268 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

Will be swapping the coil to see if the misfire moves today, and getting the computer codes.
About the seller, he's actually a brother in Christ. He knew it needed repairs. The spark plug thing was just his estimation, which was wrong. He still owes $3000 on it from buying it a year or so ago, but wanted to sell it to me for $2000. I told him how about $3000 minus cost of repairs. (It needed pads, rotors, one caliper, fluids, plugs (according to him) and now a coil pack.

Tnanks very much guys. I will update with results after I finish.


Tom Greenleaf
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Nov 24, 2020, 2:54 PM

Post #7 of 20 (266 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

Do the "swaptronics" is efficient IMO not just parts tossing. HT mentioned NGK (I thought those were OE for this) do dump the Autolites when you find out what you are dealing with.
The compression can be very helpful to see if this is serious or we don't really know yet. It's true though, just driving it running all wrong is going to cause a disaster if it wasn't to begin with?
Codes for sure just be warned those are info to use not telling you WHAT to replace. Beware of parts look ups overselling based on codes you risk lousy new parts vs good old or easily original parts depends on what you are fixing or doing.


It's enough miles IMO so care for oil changing if this turns out to be OK will help and always does to change on time or early depending on type of use,


T



Hammer Time
Ultimate Carjunky / Moderator
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Nov 24, 2020, 3:06 PM

Post #8 of 20 (264 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In


Quote
He still owes $3000 on it from buying it a year or so ago, but wanted to sell it to me for $2000.


How do you expect to get a title if there is still money owed on it. There must be a lien.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



J.cogitation
User

Nov 24, 2020, 3:11 PM

Post #9 of 20 (260 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

He's a trustworthy brother. Going into the Marines. Won't need the car but will be able to pay it off. I was going to do a bill of sale with him, and just wait on it to work out.

Concerning the NGK vs Autolite... didn't know it was that serious. If it will really make that big of a difference, I will drop another $40 on the right plugs. Can one of you guys hit me with a link to exactly the right ones to get?


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 24, 2020, 3:20 PM

Post #10 of 20 (253 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

Do the compression first so know if this engine is toast or not. It's so damaging to run an engine with one failed cylinder it might be serious trouble? 1st things first then on, Tom


Hammer Time
Ultimate Carjunky / Moderator
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Nov 24, 2020, 3:21 PM

Post #11 of 20 (253 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

How do you expect to register the car without a title?

You can't get insurance or license plates without a title.

The parts stores will tell you they work fine but trust me, they do not.

https://www.amazon.com/...k-Plug/dp/B004A73PCE

You can also use Denso in that car but they are more money


https://www.amazon.com/...k-Plug/dp/B002M2MLYM



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 24, 2020, 3:24 PM)


J.cogitation
User

Nov 24, 2020, 5:06 PM

Post #12 of 20 (239 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

Update:

Used OBD scan tool. Fault codes detected before swapping ignition coils #2 and 3:

P0303 - Cylinder 3 Misfire Detected
P0106 - Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem

After swapping ignition coil #2 and 3, car didn't start on first turn of the key. Turned again and held a little and after 2 or so seconds it started, but was not running well. The fault codes detected after restarting the engine (I did not clear the codes):

P0303 - Cylinder 3 Misfire Detected
P0106 - Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
P0302 - Cylinder 2 Misfire Detected
B2aaa - Unknown code - More information may be available on web

So it sounds like bad ignition coil. Ordering a Denso 673-8305 Ignition coil, which is the OEM part.

What about the other codes? How can I clean out cylinder 3 effectively but also hopefully inexpensively?


J.cogitation
User

Nov 24, 2020, 5:13 PM

Post #13 of 20 (233 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In


In Reply To
Do the compression first so know if this engine is toast or not. It's so damaging to run an engine with one failed cylinder it might be serious trouble? 1st things first then on, Tom


I will try to get up to O'reilly's to get a compression test kit. The ignition coil swap seemed to show that's the source of the initial problem.

Trying to get to work (Uber/Doordash) asap, so I can pay back loans to get car running. It's not crucial to start immediately, but I really hope I can get started within a week at most.


J.cogitation
User

Nov 24, 2020, 5:15 PM

Post #14 of 20 (231 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

"How do you expect to register the car without a title?"

Maybe I need to get on his insurance and drive with the title in his name for a while until it gets paid off. I hadn't gotten to that point yet. Still repairing the car. He's trustworthy, so it's no issue about him ripping me off.


Hammer Time
Ultimate Carjunky / Moderator
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Nov 24, 2020, 5:43 PM

Post #15 of 20 (214 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In


Quote
P0106 - Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem


You also have a MAP sensor code so check all the related wiring and vacuum source before changing the sensor.

You also should have the exhaust backpressure tested also. That constant misfire can destroy the Catalytic Converter and clog the exhaust. That can trigger a MAP sensor code also.





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



J.cogitation
User

Nov 24, 2020, 5:46 PM

Post #16 of 20 (207 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

 


(This post was edited by J.cogitation on Nov 24, 2020, 6:07 PM)


J.cogitation
User

Nov 24, 2020, 6:07 PM

Post #17 of 20 (199 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In


In Reply To

Quote
P0106 - Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem


You also have a MAP sensor code so check all the related wiring and vacuum source before changing the sensor.

You also should have the exhaust backpressure tested also. That constant misfire can destroy the Catalytic Converter and clog the exhaust. That can trigger a MAP sensor code also.


A mechanic friend will be visiting in two days (praise God for perfect timing) so he will be able to help me properly look over this.

Much appreciated.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 24, 2020, 6:54 PM

Post #18 of 20 (186 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

Back a few. If $$ is owed on this car the title isn't even in your friend's name alone yet? It's not his or yours till it's paid for! The lien holder owns it and HAS the title unless the whole world changed on that.
Compression testers: Basic ones dirt cheap to just buy. Same used for about the cost of shipping on Ebay just have to know if pressure reading is close to accurate.
That would tell volumes more about what's up with this engine already sounding like "converter" is junk mixing up code results what they really mean.


IF you don't know how to take compression tests look it up or I'll write it out you will want or need an oil squirter/oiler once the brand name Eagle was all I knew of and have still. Type I mean has a flexible hose end.
Vacuum testing also useful but I doubt rentable a cheap hand pump type works also makes vacuum for testing things maybe under $50 for a cheap one.


IDK all prices and qualities lots I have is ancient but works well still and 2-3 of each at least, Tom


J.cogitation
User

Nov 27, 2020, 2:48 PM

Post #19 of 20 (106 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

So, Update 2:

The bad ignition coil was replaced. I pulled the autolite plug from cylinder 3. Was clean as a whistle. I put the NGK plug in anyway, per recommendations.

Car started up fine, but idled up at 1500 rpms, and had a slight tick at around ~5 Hz, but on a friend with some experience's recommendation, I drove it around for about 45 minutes on the highway.

Tick gone, misfire gone, idling at 600rpms, smooth, and check engine light off.

My friend thought he had a compression tester kit to bring with him, but he couldn't find it. Is it very important to have that done still? I plan on replacing with the new NGK plugs within a week or so, per everyone's recommendations, but can't do that immediately.

I do want to do whatever I can to responsibly care for the engine. I hope to get another 100,000 miles out of it, if possible.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 27, 2020, 3:27 PM

Post #20 of 20 (102 views)
Re: 2013 Hyundai Elantra - Misfiring and bad idling Sign In

Notes: OK so what you did worked and took some time (expected) to get a normal idle - it's learning from back when covering up the dead cylinder. The makes compression test LESS mandatory now IMO. If you wanted watch (credible idle speed) and cancel cylinders ONE at a time but quickly. Look at the reaction of idle if all the same is a strong reason to believe all are close enough.


IMO and not alone you lucked out. I would quickly do an oil and filter change it's been wrecked from a misfire and cheap - just get the engine oil OUT totally. If fuel in it is trouble so don't guess just change it.


How far you want this to go is nuts. It might and do more or fail in a day there's just no perfect way to assure how far you get. Not allowing an engine to run poorly for long along with all suggested maintenance always look for leaks and what fluids are low find out if normal or it means something wrong.


Brake fluid will lower with wear from known new mark. Coolant is very temperature sensitive (volume of it) expands and contracts so there are marks for "HOT" and "COLD" on where you fill it. Those extremes vary by right where you are quite a bit for the cold level if used to the below zero crap coming - dammit.


Glad you're back to NGK it does matter.


Last is if converter was harmed? Unknown for now but when this run perfectly long enough taking it for a hard and fast RPM ride can burn off some yuk collected AYOR driving like that of course.


Good luck you seemed to already have some!


T







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