# 2013 Hyundai Elantra - Engine Misfires/Bad Idling **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** hyundai\ **Created:** [November 24, 2020, 5:00am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627 "2020-11-24T05:00:48Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![j.cogitation\_172512](https://avatars.discourse-cdn.com/v4/letter/j/d9b06d/32.png) [@j.cogitation\_172512](https://community.cartalk.com/u/j.cogitation_172512)\ **Post date:** [November 24, 2020, 5:00am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/1 "2020-11-24T05:00:48Z")
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. 🙂 ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [November 24, 2020, 5:32am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/2 "2020-11-24T05:32:33Z")
To start with, never buy a car that just needs a cheap and easy fix. If there was a cheap and easy fix, the previous owner would have done it before he sold it. Is the check engine light on? If it isn’t, does it light up when you turn the ignition of without starting the engine. The check engine light is designed to tell you what system is having abnormal readings. Change the ignition coil from the sooty cylinder to a different cylinder. Does the misfire move with it. If yes, replace that coil. If not run a dry and wet compression check. ---
**Author:** ![j.cogitation\_172512](https://avatars.discourse-cdn.com/v4/letter/j/d9b06d/32.png) [@j.cogitation\_172512](https://community.cartalk.com/u/j.cogitation_172512)\ **Post date:** [November 24, 2020, 7:20am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/3 "2020-11-24T07:20:51Z")
First, I appreciate the fast answer. “Never buy a car that needs a cheap and easy fix” Understood. In this case, it was a friend letting me have the car, so I can start working, and I will pay him back once I have income. He said he expected repairs to be around $1000 and lowered his price to $2000. “Is the check engine light on?” Yes. I haven’t gotten up to Autozone yet to get the codes. “Change the ignition coil from the sooty cylinder to a different cylinder. Does the misfire move with it. If yes, replace that coil. If not run a dry and wet compression check.” Can move the ignition coil by myself, I believe. The dry and wet compression check… Can I borrow a compression test kit from a shop? I watched a video on Youtube. Near the edge of what I can do from watching a video, I’m guessing. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [November 24, 2020, 8:27am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/4 "2020-11-24T08:27:55Z")
See if Advance or Autozone have a compression tester in their free tool loaner program. Don’t forget to prop the throttle open. Running a compression check is a piece of cake compared to replacing a head. ---
**Author:** ![j.cogitation\_172512](https://avatars.discourse-cdn.com/v4/letter/j/d9b06d/32.png) [@j.cogitation\_172512](https://community.cartalk.com/u/j.cogitation_172512)\ **Post date:** [November 24, 2020, 9:38pm UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/5 "2020-11-24T21:38:24Z")
Will try swapping the coil first. If that doesn’t work, compression tester I will move to next. Will update with results. Thanks, sir. ---
**Author:** ![j.cogitation\_172512](https://avatars.discourse-cdn.com/v4/letter/j/d9b06d/32.png) [@j.cogitation\_172512](https://community.cartalk.com/u/j.cogitation_172512)\ **Post date:** [November 25, 2020, 12:07am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/6 "2020-11-25T00:07:10Z")
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? ---
**Author:** ![davepsinbox\_157004](https://avatars.discourse-cdn.com/v4/letter/d/73ab20/32.png) [@davepsinbox\_157004](https://community.cartalk.com/u/davepsinbox_157004)\ **Post date:** [November 25, 2020, 12:13am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/7 "2020-11-25T00:13:20Z")
P0106 could be a vacuum leak or a bad MAF sensor. Do a visual inspection for possible vacuum leaks. ---
**Author:** ![j.cogitation\_172512](https://avatars.discourse-cdn.com/v4/letter/j/d9b06d/32.png) [@j.cogitation\_172512](https://community.cartalk.com/u/j.cogitation_172512)\ **Post date:** [November 25, 2020, 12:29am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/8 "2020-11-25T00:29:11Z")
I will have a friend who knows more help me look for vacuum leaks, but the engine bay looks in very good shape. Thanks for info. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [November 25, 2020, 2:17am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/9 "2020-11-25T02:17:59Z")
> [@j.cogitation\_172512](#): > > P0106 - Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem The misfire is causing low engine manifold vacuum, the MAP input to the computer is abnormal and considered out of range. After repairing the misfire, P0106 should not return. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [November 25, 2020, 2:50am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/10 "2020-11-25T02:50:21Z")
Clean or replace the plug in cylinder 3 also. ---
**Author:** ![j.cogitation\_172512](https://avatars.discourse-cdn.com/v4/letter/j/d9b06d/32.png) [@j.cogitation\_172512](https://community.cartalk.com/u/j.cogitation_172512)\ **Post date:** [November 27, 2020, 9:46pm UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/11 "2020-11-27T21:46:30Z")
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. ---
**Author:** ![davepsinbox\_157004](https://avatars.discourse-cdn.com/v4/letter/d/73ab20/32.png) [@davepsinbox\_157004](https://community.cartalk.com/u/davepsinbox_157004)\ **Post date:** [November 29, 2020, 12:01am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/12 "2020-11-29T00:01:34Z")
If the car is running normally I wouldn’t worry about a compression test. That was only if the coil wasn’t the problem. Glad to hear you got the issue solved. ---
**Author:** ![Laisseraller](https://avatars.discourse-cdn.com/v4/letter/l/ee7513/32.png) [@Laisseraller](https://community.cartalk.com/u/Laisseraller)\ **Post date:** [November 30, 2020, 1:11am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/13 "2020-11-30T01:11:25Z")
Old school a miss fire ment spark plug, or coil now days with fuel injection a miss fire most likely a injector is leaking or not working properly, switching coil packs may help ID which cylinder, injectors testing is best I found one company out of AZ which make sure your new injectors have bal pressure by matching OMS reading. ---
**Author:** ![wentwest](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wentwest/32/6073_2.png) [@wentwest](https://community.cartalk.com/u/wentwest)\ **Post date:** [December 1, 2020, 4:18am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/14 "2020-12-01T04:18:55Z")
I’ve never worked on a Hyundai, but on my 2002 Mazda Miata I had a similar experience with a misfire. After going through all the diagnostics you have been discussing, and more, I finally was told to check the valve lash (the maximum space between the cam lobes and the valves). The lash was tight on every exhaust valve. I fixed that and when I buttoned up the engine and started it the first time, I knew that the problem was solved. The engine started fast and run so much better, it was shocking. The check engine light never went on again, fuel mileage went up, and happiness filled the garage. So that’s my suggestion. ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [December 1, 2020, 11:01pm UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/15 "2020-12-01T23:01:19Z")
> [@wentwest](#): > > happiness filled the garage. With my 4 previous Hondas ('75 Civic, '81, '85, '88 Accords) adjusting valve lash was THE most satisfying DIY maintenance for me. ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [December 2, 2020, 12:13am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/16 "2020-12-02T00:13:25Z")
American designed engines (with a couple exceptions) have been using hydraulic valve lash adjustment since world war 2. Why do Honda and some other companies persist in using an antiquated system requiring periodic adjustment? ---
**Author:** ![wentwest](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wentwest/32/6073_2.png) [@wentwest](https://community.cartalk.com/u/wentwest)\ **Post date:** [December 2, 2020, 4:29am UTC](https://community.cartalk.com/t/2013-hyundai-elantra-engine-misfires-bad-idling/172627/17 "2020-12-02T04:29:56Z")
Nissan does it, too. I suspect there’s some performance reason, but maybe it’s just cheap. Anyway, it’s not a fun job but it sure made a difference.