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Discussion Starter #1
Today I had a strange problem with my 2014 Elantra. I get off work, jump in, start car (Temp 47#F). Cranks right up, as usual. I hear a faint tapping sound, so I tap the gas pedal and bring the RPM to 2500. Engine dies as though I shut it off.

Restart one: Normal crank sound but no start
Restart two: Normal Crank, starts to hit, but never catches.
Restart three: Starts to hit more, starter bangs around like engine misfiring.
Restart four: Engine starts. I bring revs to 2500, engine immediately dies.
Restart five: Normal Crank, but no spark, sounds like no compression.
Restart six: Normal Crank, but no spark, sounds like no compression.
Restart seven: Normal Crank, starts to hit, but never catches.
Restart eight: Starts to hit more, starter bangs around like engine is misfiring
Restart nine: Engine starts. Idles low (500rpm) but continues to run.

At this time, I have already called for a tow, called the stealer to let them know I was on my way, So having time, I drive the car around the parking lot. Runs good. I get brave and drive down the road. All is good. I get braver and drive to the Stealer which is about 12 miles away. Car runs perfect. I get to the place, tell the Service writer my issue, and he looks stumped, but says they will look at it. An hour later it comes back, ready to go, with a "can not duplicate" repair. Car has 91K on it, has Never had an issue whatsoever. Never did anything like this before. Started perfectly every time (about 7-8 starts) at the stealer. Said noting they can do, if it does it again, they have it on history now, and will go from there. So wife shows up, we take her car, go get something to eat, come back about 90 minuted later. Car is cold again, just like at work earlier. I get in, start it, fires right up. I bring rpm's to 2500 again, remains running. Drive 37 miles home. No issues. Even coasted down a hill in Neutral, revved engine and let off gas to see if it would stall. I stayed running.

What in the world happened here? Component failing somewhere? Sensor? Glitch in the Matrix? I am at a loss. The only thing that even remotely crosses my mind is fuel pump/pressure issue.But never an issue before, and since. Has anyone had any problem like this or maybe point me in a direction?
 

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Did the stealer scan it for codes? Can you post a pic of the work order?
 

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Discussion Starter #3 (Edited)
Yes, No Codes found.

Just states :
C/S Vehicle will intermittently start and die with rough idle. Check with advise.
Ran GDS scan no codes found could not duplicate concern
could not duplicate customer concern at his time . Vehicle is operating as designed.

Complimentary multi-point inspection report card as a complimentary service to you from Crain Hyundai.
Completed courtesy inspection. Thank you for choosing us. We value your business.

Invoice number H1CS706902
Cust Number 1245685
 

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Discussion Starter #4
Just an update, started it this morning, 52*F, fired right up, let it idle 15 seconds. Blipped throttle to 2500, started to stall. I rapidly tapped the gas, it gurgled and chugged, then smoothed out. I idled at 1000. Revved again and no issue. Drove car. Went up hill and left it in 6th, to the floor. No starvation or other issue. Got to next hill, let it downshift on its own while to the floor. Engine climbed normally to 5k before I let off. Could not duplicate problem since.

Going to try to reproduce problem on my lunch break. Any help or ideas welcome.
 

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Do you have a live data scan tool? I would like to look at engine speed (rpm) and Throttle sensor when this happens. I would think the engine speed (crank sensor) or TPS would flag a code if they were the problem but never know. Another PID to monitor would be load, MAF.
 

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My tool is very limited in its scope. It is about 6 years old. Video of what it does...

https://vimeo.com/320882539
What tool? Only seen the gauges WITHOUT a tool.
That being said. I think the engine torque is pulling on a wiring harness and causing the stall. I would wiggle test the harness on the engine and going to the crank sensor in particular.
 

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Discussion Starter #10
What tool? Only seen the gauges WITHOUT a tool.
That being said. I think the engine torque is pulling on a wiring harness and causing the stall. I would wiggle test the harness on the engine and going to the crank sensor in particular.
You had asked earlier of I had a live scan tool. I described what I had, the video I posted was me able to reproduce the problem, so it could be seen. I drove car 335 miles today, had no issues, can’t duplicate issue after engine has run for over a minute.


:confused:
 

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I have seen this before on daughters 2016 and you are closer to your guess with "glitch in the matrix" than you think. Try this next time the engine is truly cold (more than 90 minutes, more like several hours). Turn the key to the "On" position but wait about 3-5 seconds before cranking. If it starts normally, don't give it gas, just leave it alone for about 30 seconds. When I have seen this there were no codes set, but it seemed the ECM was either getting a slow read from a cold sensor or some other thing that "confused" the ECM causing it to incorrectly set the fuel mix. All difficult to prove exactly what happened, but after doing the above procedure the problem resolved itself.

I have also seen this happen in near freezing weather when the engine was restarted after about an hour. Engine not fully cold, but not really warm either. Just by turning the engine off when it didn't start "cleanly", then starting using the method described above, cleared the issue. I have had my 2014 2.0L EGT do this a couple of times, too. And your description is spot on; if it starts right up and seems fine, it will run normally and go on down the road. If it doesn't start cleanly, it takes it a bit of time to get its act together, or even turn it off and start over. But one thing I have found is that many of these drive by wire systems need a few seconds after starting to settle in. No throttle change immediately after starting, but a few seconds to see where the sensors are reading.

And the GDI engines (2.0L in the GT among others) do some weird stuff after a cold start to "light off" the catalytic converter quickly and reduce cold engine emissions and also spray a small amount of fuel on the back sides of the intake valves. Per Hyundai's description, there is a second injector pulse while the intake valve is open into the fuel spray path. Makes the thing run rich which heats up the converter fast, and also holds the engine at a faster than normal cold idle for about 30 seconds. Not sure if the 1.8L MPI engine does the same as it's injectors are "up stream" and always hit the backside of the intake valves with fuel/air, but may still be used to light off the converter.
 

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Discussion Starter #12
I have seen this before on daughters 2016 and you are closer to your guess with "glitch in the matrix" than you think. Try this next time the engine is truly cold (more than 90 minutes, more like several hours). Turn the key to the "On" position but wait about 3-5 seconds before cranking. If it starts normally, don't give it gas, just leave it alone for about 30 seconds. When I have seen this there were no codes set, but it seemed the ECM was either getting a slow read from a cold sensor or some other thing that "confused" the ECM causing it to incorrectly set the fuel mix. All difficult to prove exactly what happened, but after doing the above procedure the problem resolved itself.

I have also seen this happen in near freezing weather when the engine was restarted after about an hour. Engine not fully cold, but not really warm either. Just by turning the engine off when it didn't start "cleanly", then starting using the method described above, cleared the issue. I have had my 2014 2.0L EGT do this a couple of times, too. And your description is spot on; if it starts right up and seems fine, it will run normally and go on down the road. If it doesn't start cleanly, it takes it a bit of time to get its act together, or even turn it off and start over. But one thing I have found is that many of these drive by wire systems need a few seconds after starting to settle in. No throttle change immediately after starting, but a few seconds to see where the sensors are reading.

And the GDI engines (2.0L in the GT among others) do some weird stuff after a cold start to "light off" the catalytic converter quickly and reduce cold engine emissions and also spray a small amount of fuel on the back sides of the intake valves. Per Hyundai's description, there is a second injector pulse while the intake valve is open into the fuel spray path. Makes the thing run rich which heats up the converter fast, and also holds the engine at a faster than normal cold idle for about 30 seconds. Not sure if the 1.8L MPI engine does the same as it's injectors are "up stream" and always hit the backside of the intake valves with fuel/air, but may still be used to light off the converter.
If I do not touch the gas it will run fine, so what you are stating makes sense. My only worry was if I had to go fast, like emergency or something, I don’t need the car dying when it goes above 2K.

So what I am getting is that your “waiting period”, then start, cured your “glitch in the matrix”?
 

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Discussion Starter #15
Must be a slow sensor, then. Has done it twice since, once after a 330 mile trip, then today (a day after the return trip). I am wondering, if there is a separate cold sensor for the engine, VS the temp gauge. I had an old Gtand prix thst was like that, one sensor for the ECM, the other for the cars temp gauge. Petgaos something like that..

For this issue to suddenly start from nowhere is what concerns me
 

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Discussion Starter #16
OK, had a weird one today. Started, drove off, hit 2500, let off, car dies on the road. Does the "no compression" sounding start thing. So I retry, does it a couple more times, I wait, and try again, this time, on the dash lights, a big "ES" shows up, where the battery light is. I thought I was seeing things, but I got it to come back two more times. Big, bold letters, ES. I cranked it again, and it did its one cylinder fire, then started up. it ran on 3 cylinders for about 90 seconds before it finally hit all 4. STILL NO Check Engine light!! Ran fine the rest of teh way home.

What is going on here???? What is this light? It does not appear normally. Is it some kind of Hyundai diagnostic light?

Note. Drove car 330 mile X2 trip to KC and back here this weekend. Had one instance, otherwise ran well, and averaged 38MPG.
 

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Sorry to drag up an old post but I’m having the same issue. They replaced the spark plugs, coils, connectors and fuel injectors and I’m $2K into repairs and the problem is still happening!

was there any answer or resolution to this problem??
 

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Discussion Starter #18
Yes, I bought a crankshaft position sensor and replaced it myself. My problem has been gone since. Even though I had no CE light, I got the idea from a YouTube video that described a no start condition. The guy checked the crank sensor, and while it showed a nice waveform, indicating it was operating, it did show as weak, and irregular. Not enough to throw a code, but enough to cause the issue. I ordered an OEM from Amazon, was cheap, and took about 30 minutes to install.
 

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Strangest symptom of a CPS; vehicle ran fine, started perfectly. No unexpected shutdowns under normal operation. But try and take the engine over 4500 rpm and the fuel injection shut off. The CPS was "weak" and couldn't detect the magnet in the crankshaft if it went by too fast. No detection = engine not turning = shut off the fuel. One reason this is done is to shut off the fuel flow in the event of an accident.

But when pulling out to pass and winding out the engine it is quite the surprise when the engine shuts off!
 
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