2012 Chevy Sonic - P0301 (Cylinder #1 misfire)

[Number_35]

This is my regarding my friend's 2012 Sonic. I've posted about various repairs previously.

It started running terribly, and the CEL was flashing. He wisely has not been driving it since this started.

I went over this evening and read a P0301 (Cylinder #1 misfire). The engine is the NA 1.8. We did the plugs, valve cover, and coil pack two or three years ago - the plugs were very badly oil-fouled due to a very brittle valve-cover gasket leaking oil into the spark plug wells, which had a lot of oil in them. I suspect the fouled plugs stressed the original coil, causing it to fail prematurely.

This evening I pulled the #1 plug, and it looked OK. I assumed #1 was on toward the R (passenger) side of the engine bay (L as viewed from the front), which is the side the TB cover, serpentine belt, and accessories are on. But to be sure I pulled the plug at the other end (#4 I assume). I also swapped the #1 and #2 plugs, to see if the code would follow the plug. It did not - the misfire continued to trigger a P0301.

The coil pack is a one-piece unit, so I couldn't swap individual coils.

At this point I think the best course of action would be to replace the coil pack on speculation. (The replacement coil of two or three years ago was from an auto-parts store in the small town where the car was. I don't remember the brand or country of origin. It's quite likely it has failed.)

I wonder, though, whether a defective fuel injector would cause a misfire. I presume a misfire code applies to the spark, not the presence or absence of fuel.

Thoughts? Thanks!

 

[Timmastertech]

The way the PCM determines a misfire is by looking at acceleration and deceleration of the crankshaft based on the crankshaft position sensor input. The PCM knows that as a cylinder fires the crankshaft should speed up then start to slow down as the next cylinder comes up on compression stroke. If the crankshaft does not accelerate sufficiently the PCM judges that a misfire occurred. The PCM has no clue why that cylinder misfired, just that it did not fire. It could be a spark issue, a fuel issue or a mechanical issue. To test any vehicle with ignition components close coupled to the spark plugs (no spark plug wires) I use a set of high tension extension leads . This allows me to either disconnect single cylinders to use a spark tester and gives me a place to attach a secondary ignition pickup to view a secondary ignition waveform.

 

[Number_35]

The way the PCM determines a misfire is by looking at acceleration and deceleration of the crankshaft based on the crankshaft position sensor input. The PCM knows that as a cylinder fires the crankshaft should speed up then start to slow down as the next cylinder comes up on compression stroke. If the crankshaft does not accelerate sufficiently the PCM judges that a misfire occurred. The PCM has no clue why that cylinder misfired, just that it did not fire. It could be a spark issue, a fuel issue or a mechanical issue. To test any vehicle with ignition components close coupled to the spark plugs (no spark plug wires) I use a set of high tension extension leads . This allows me to either disconnect single cylinders to use a spark tester and gives me a place to attach a secondary ignition pickup to view a secondary ignition waveform.

Great idea - thank you so much! I knew I saved those old plug wires for a reason - I'll see what I can rig up.

 

[Lubener]

Since you have a one piece coil, I am assuming there are plug wires. If you still have an old school timing light, you can clamp it one # 1 and see if the timing light fires and then compare it to the other cylinders. If it is a plug wire, most likely the insulation is breaking down. At night you can use a spray bottle and spray the # 1 plug wire and see if it arcs. You can also compare resistance of the suspect wire to the others of similiar length.

 

[Number_35]

Since you have a one piece coil, I am assuming there are plug wires. If you still have an old school timing light, you can clamp it one # 1 and see if the timing light fires and then compare it to the other cylinders. If it is a plug wire, most likely the insulation is breaking down. At night you can use a spray bottle and spray the # 1 plug wire and see if it arcs. You can also compare resistance of the suspect wire to the others of similiar length.

Unfortunately there are no plug wires - the coil pack sits over the spark-plug wells, and has conical projections that go down to feed the plugs.

I'm pondering workarounds - if there's enough slack in the wiring harness, I can twist the coil pack sideways, insert the spark plugs into the points of the cones, run jumpers from the plugs' ground electrodes to ground and watch for spark.

Another possibility - leave the plugs in the engine, and try to run old plug wires (which I have) between the coil pack and ground. Use a timing light (as you suggested) to check for spark.

 

[Number_35]

I wonder if I can test the coil pack with an ohmmeter. I don't have a schematic, but figure that there are four primary windings which should yield a low resistance. (Or perhaps only two, if it's a waste-spark system.)

I'm not sure how the four (or two) secondary windings would be tested - the one end would be the contact to the spark plug, but I'm not sure about the other. I guess it would have to be present at the connector.

All of this assumes that there's an open circuit rather than a short.

 

[atikovi]

Throwing a new coil pack at it might be the simplest thing to try and cheaper than an hour diagnostics at a shop. Not a whole lot else that might cause it unless something internal let go. Jut buy a good name brand like AC Delco, Delphi, Hitachi, etc. or you might be doing this again in a year or two.

 

[Number_35]

Throwing a new coil pack at it might be the simplest thing to try and cheaper than an hour diagnostics at a shop. Not a whole lot else that might cause it unless something internal let go. Jut buy a good name brand like AC Delco, Delphi, Hitachi, etc. or you might be doing this again in a year or two.

I was thinking the same. The diagnostic time would be mine, so free, but I don't like to waste time regardless.

Those brands you listed were the same ones that came up on RA that I thought looked good.

 

[Marcozi]

Check the engine harness connector for cylinder 1. Make sure the contacts are clean. Also, most coils (and fuel injectors) are fired via a metal oxide substrate field effect transistors (MOSFET; https://en.wikipedia.org/wiki/MOSFET#:~:text=The metal-oxide-semiconductor field,the conductivity of the device.). They can go bad. But, they are readily available (www.mouser.com) and fairly easy to replace.

 

[Number_35]

Check the engine harness connector for cylinder 1. Make sure the contacts are clean. Also, most coils (and fuel injectors) are fired via a metal oxide substrate field effect transistors (MOSFET; https://en.wikipedia.org/wiki/MOSFET#:~:text=The metal-oxide-semiconductor field,the conductivity of the device.). They can go bad. But, they are readily available (www.mouser.com) and fairly easy to replace.

Thank you! I have a vague memory of studying FETs back in college many years ago. From the memory banks, were they the semiconductor equivalent of an old tube in operation? (That is, rather than amplifying C-E current proportionately to B-E current, did they amplify on the basis of input voltage? Arg, it's been too long ...)

Where would the MOSFET(s) be located - is there an ignition-driver module separate from the ECU?

 

[Number_35]

Check the engine harness connector for cylinder 1. Make sure the contacts are clean. Also, most coils (and fuel injectors) are fired via a metal oxide substrate field effect transistors (MOSFET; https://en.wikipedia.org/wiki/MOSFET#:~:text=The metal-oxide-semiconductor field,the conductivity of the device.). They can go bad. But, they are readily available (www.mouser.com) and fairly easy to replace.

Arg, I just realized that checking for spark out of the coil would not eliminate the possibility of a bad input to the coil.

 

[Number_35]

My best price on a coilpack locally is C$197 + 12% sales taxes.

 

[Number_35]

I pondered all of the pros and cons of proceeding with trying to rig up a way to test the existing coilpack in the Sonic, and did a bunch more reading. At the end of the day, people's experience is that it's almost always the plugs or the coil. Given that the trouble code did not track the plug (which I moved to a different cylinder), the problem is likely the coil.

Given also that my time is worth something and I have a lot of things on the go, with my friend's permission I ordered the coilpack from Rock Auto. (I posted the discount code in the appropriate thread here on BITOG.)

Went for the AC Delco for C$124.37. With taxes, it will come to about C$140 plus half the shipping. I combined his order with oil filters for the three vehicles in my family, with everything shipping from the same location, so I'll pay half the shipping cost.

The order is scheduled for delivery July 6th.

Edit: I don't know the brand of the one quoted locally. May have been the same as the 1st replacement that only lasted 2 or 3 years.

 

[zzyzzx]

At this point I think the best course of action would be to replace the coil pack on speculation. (The replacement coil of two or three years ago was from an auto-parts store in the small town where the car was. I don't remember the brand or country of origin. It's quite likely it has failed.)

Still have the receipt? does it have a warranty?

 

[Number_35]

Still have the receipt? does it have a warranty?

I would be almost certain that my friend did not save the receipt. But two or three years later, it's probably moot.

 

[zzyzzx]

Check the engine harness connector for cylinder 1. Make sure the contacts are clean. Also, most coils (and fuel injectors) are fired via a metal oxide substrate field effect transistors (MOSFET; https://en.wikipedia.org/wiki/MOSFET#:~:text=The metal-oxide-semiconductor field,the conductivity of the device.). They can go bad. But, they are readily available (www.mouser.com) and fairly easy to replace.

I was wondering why these things seemingly went bad so often when a regular coil that cars use to use almost never went bad.

 

[Number_35]

I was wondering why these things seemingly went bad so often when a regular coil that cars use to use almost never went bad.

Yup, the old discrete cylindrical coils seemed to last a long time.

 

[zzyzzx]

I would be almost certain that my friend did not save the receipt. But two or three years later, it's probably moot.

I was thinking of the possibility of a lifetime warranty situation.

 

[Number_35]

I was thinking of the possibility of a lifetime warranty situation.

I should have asked - never thought about it.

 

[97prizm]

This is my regarding my friend's 2012 Sonic. I've posted about various repairs previously.

It started running terribly, and the CEL was flashing. He wisely has not been driving it since this started.

I went over this evening and read a P0301 (Cylinder #1 misfire). The engine is the NA 1.8. We did the plugs, valve cover, and coil pack two or three years ago - the plugs were very badly oil-fouled due to a very brittle valve-cover gasket leaking oil into the spark plug wells, which had a lot of oil in them. I suspect the fouled plugs stressed the original coil, causing it to fail prematurely.

This evening I pulled the #1 plug, and it looked OK. I assumed #1 was on toward the R (passenger) side of the engine bay (L as viewed from the front), which is the side the TB cover, serpentine belt, and accessories are on. But to be sure I pulled the plug at the other end (#4 I assume). I also swapped the #1 and #2 plugs, to see if the code would follow the plug. It did not - the misfire continued to trigger a P0301.

The coil pack is a one-piece unit, so I couldn't swap individual coils.

At this point I think the best course of action would be to replace the coil pack on speculation. (The replacement coil of two or three years ago was from an auto-parts store in the small town where the car was. I don't remember the brand or country of origin. It's quite likely it has failed.)

I wonder, though, whether a defective fuel injector would cause a misfire. I presume a misfire code applies to the spark, not the presence or absence of fuel.

Thoughts? Thanks!

My geo prizm from many years ago, the #1 spark plug wire would go bad about every 4-5 years. It was the shortest very left wire if you're in the car. Check engine light flashing. It looked ok but a new wire solved the problem.