Number two cylinder misfire

Tiny
LOREN STOVER
  • MEMBER
  • 2000 HYUNDAI ELANTRA
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 150,236 MILES
At first I had a p0300 p0301 and p0303. Then I replaced plugs wires and fuel filter and fuel pump and that went away. Now I have a p0302 and I looked for vacuum leaks also cleaned the throttle body and AIC valve and MAF sensor. I wanted to check the ohms on the coil connector but I don't know what the specs are for this coil pack. I also checked the injectors with a mechanics scope and they are working as desired. I am lost and don't know what else to do. I have never had trouble checking and fixing one simple misfire.
Do you
have the same problem?
Yes
No
Wednesday, December 9th, 2020 AT 2:10 PM

76 Replies

Tiny
STEVE W.
  • EXPERT
As that is a waste spark system that uses both ends of each coil for spark (1 and 4, 3 and 2) a quick test of the coil would be to reverse the #2 and #3 plug wires on that coil. If you now get a P0303 you know it's the coil because it's now not firing the plug on 3 but is firing the one on 2. If it stays the P0302 code then it's in that cylinder, either a valve or similar. Then it's time to do things like a compression test and a leakdown test.
I suspect you will find it's the coil. As for a resistance check, they don't show a test for the secondary side and if it was a primary side fault you would get a code for that and have 2 cylinders not operating.
Was this
answer
helpful?
Yes
No
+1
Wednesday, December 9th, 2020 AT 3:51 PM
Tiny
LOREN STOVER
  • MEMBER
I scanned live data after I changed or rather switched number two and number three wires on the coil and this is what I came up with but I did not get a check engine light.
Was this
answer
helpful?
Yes
No
Wednesday, December 9th, 2020 AT 5:39 PM
Tiny
STEVE W.
  • EXPERT
Those fuel trims are very strange. If they are correct they show that engine running very rich. Ideally they should be running closer to zero. A negative number means they are pulling fuel away from the system. What is the tool you are using?
Was this
answer
helpful?
Yes
No
Wednesday, December 9th, 2020 AT 7:40 PM
Tiny
LOREN STOVER
  • MEMBER
It's an Autel Bluetooth scan tool.
Was this
answer
helpful?
Yes
No
Wednesday, December 9th, 2020 AT 9:02 PM
Tiny
STEVE W.
  • EXPERT
Swap the wires back and see if it returns. If it doesn't look close in the towers where the wires connect and see if the inserts are corroded or have another issue. It may still be a bad coil and moving the wires made it work but?
Was this
answer
helpful?
Yes
No
Wednesday, December 9th, 2020 AT 9:49 PM
Tiny
LOREN STOVER
  • MEMBER
If I remove the boot from #2 cylinder it will arc across #2 and #3 towers on the coil. I don't know if that's normal or not.
Was this
answer
helpful?
Yes
No
Wednesday, December 9th, 2020 AT 10:43 PM
Tiny
STEVE W.
  • EXPERT
Normal. That is the spark looking for a ground. Not a good test though as you can damage the coil doing that.
Was this
answer
helpful?
Yes
No
Wednesday, December 9th, 2020 AT 11:44 PM
Tiny
LOREN STOVER
  • MEMBER
When the p0302 code illuminates the light also blinks and I forgot to mention I have a pending code for a small EVAP leak. If I press the gas pedal and let it go the car will stall but starts right back up and the fuel trims were -25 and -75 at one time when I checked live data yesterday. So i'm guessing it might be running rich. So I just need to know what to do next. Thanks
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 5:54 AM
Tiny
LOREN STOVER
  • MEMBER
One other thing I didn't mention; I checked all cylinders compression and #1 #2 and #3 cylinders were about 210 PSI and #4 was 190.
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 5:59 AM
Tiny
STEVE W.
  • EXPERT
The 302 code flashing is indicating it is a true misfire and constant. The light flashes to tell you that it could be doing damage to the converter due to the raw fuel going into it.

The compression numbers are a bit high, if it's running rich then that could be carbon build up, however I would also try a different scan tool to see if the trims agree with what you are seeing, most systems top out at -25 and anything above that triggers codes so I suspect the numbers may not be correct, that happens sometimes if a scan tool doesn't read data correctly on a particular vehicle. One of the reasons why most shops have 2 or more scan tools, they all have odd quirks.
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 9:01 AM
Tiny
LOREN STOVER
  • MEMBER
Do I need to let the vehicle warm up to operating temperature before I check the trim numbers?
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 9:06 AM
Tiny
LOREN STOVER
  • MEMBER
Really quick question. When I hook a smoke machine up to the line from the brake booster I have smoke coming out of the number one cylinder. Can you tell me what that could be? Thank you
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 11:02 AM
Tiny
STEVE W.
  • EXPERT
Yes, all testing should be done on a warmed up engine, that assures the converters are working and the PCM is in control. The smoke is likely because the intake valve is open. If you are sure the engine is at top dead center on the compression stroke and still see smoke then you have a bad valve. However I doubt that as you don't show a misfire now for cylinder one.
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 12:21 PM
Tiny
LOREN STOVER
  • MEMBER
The car is staying in closed-loop at operating temperature. Do you think maybe I have a blown head gasket? Because it did get hot a couple of times when I let someone drive it. I redid the compression test and I took all four spark plugs out this time, lol.
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 1:53 PM
Tiny
STEVE W.
  • EXPERT
190-200 is a bit high but as I said it could be carbon related. Doubt it's a head gasket as you have no signs of that. Closed loop is what you want the engine in once it warms up. That means the PCM is staying in control. One thing you could check is the PCV system, some have issues where they will get crud built up in them and then they start pulling in some oil and cause rapid carbon build up. The PCM will richen the mixture up in that case because the carbon acts like a sponge and pulls some fuel out of the mix. Then on ignition it burns and the PCM tries to compensate by removing fuel. It sounds like it runs okay, just needs a few tweaks to get it settled in. Is that a replacement engine? I see the lettering on the cover?
When you snap the throttle do you see the upstream sensor voltage change?
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 2:50 PM
Tiny
LOREN STOVER
  • MEMBER
It runs pretty straight about eight hundred RPM's until you hit the gas then it wants to bog down and shut off. Or when you put it in drive or reverse it shakes and rattles and everything else and doesn't want to go anywhere. I'm getting ready to check that Upstream sensor voltage. I'll let you know. I can definitely feel and hear the miss while sitting in the car.
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 3:42 PM
Tiny
LOREN STOVER
  • MEMBER
Upstream and downstream sensors when I flick the throttle. They both go down to 0.015 volts and that is the O2 sensors. If that's what you wanted to know. The car also tries to shut off whenever I flick the throttle. I have to give it enough throttle to keep it running.
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 3:52 PM
Tiny
STEVE W.
  • EXPERT
Okay, the fact that both drop means the converter is probably gone. It should sort of stay stable with the upstream dropping fast. If you're feeling a misfire but not setting a code I would try a different scan tool first, one that can read the misfire counters and show you which cylinder(s) is causing the problem. Especially as you should also have a converter code. From the plugs it's running rich and using some oil which may be why the converter is acting bad.

Was this a replacement engine for this car or is it the original? Asking because it's easy to get a wrong engine these days. It's also possible you have a timing issue but again the codes are not there which is why I would try a different scan tool.
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 5:13 PM
Tiny
LOREN STOVER
  • MEMBER
I don't have access to another scan tool right now. But is there anything I can do to confirm that catalytic converter is the culprit? Can't I run RPM's up a little high and put my hand over the tailpipe usually if it gets hot it means the catalytic converter is probably bad. Is that true or just a myth?
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 7:22 PM
Tiny
LOREN STOVER
  • MEMBER
Oh, and I know nothing about the history of that car so I don't know if the motor is a replacement or not. Is there anyway I could find out besides the original owners?
Was this
answer
helpful?
Yes
No
Thursday, December 10th, 2020 AT 7:23 PM

Please login or register to post a reply.

Sponsored links