Random Misfire, Flashing CEL, P0301

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Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Random Misfire, Flashing CEL, P0301

Post by Browning » Sat Jul 06, 2019 10:47 am

This will be long and probably ramble on but it's driving me nuts.

2005 Pontiac Vibe base model. 180, XXX miles. This has all been happening since Saturday.

We've been getting a really rough idle at stop lights which drops the RPM's really low but never stalls. Putting it in neutral cleared it up we could take off and go with no check engine light. Now, it has progressed to happening randomly throughout the day sometimes it clears up sometimes it continues as we take off and clear around 3,000 RPM but is accompanied by a flashing CEL for cylinder 1 misfire P0301. At one point it also threw a bank 1 lean P0171 but only once and hasn't come back. The P0301 is occurring quite a bit but it is random.

For instance, sometimes I can drive it into town without any missing or codes, other times it acts up for a bit then clears up and then another time it misses like crazy and throws the flashing CEL for the P0301.

Things I have done already:

1. Chevron in the tank
2. Changed plugs (Autolite iridium)
3. New coil (also swapped around and the code did not follow)
4. New Air filter
5. Cleaned and then replaced MAF sensor
6. Checked for vacuum leaks but I couldn't find any

Went for a ride today after changing the MAf and it ran good for 15 minutes then started acting up. Got home, restarted it still rough. Rinse and repeat and it cleared up on like the 3rd restart but if you gas it fast there's a quick hesitation before it revs.

From all of the reading I've done the last couple of days from mostly here other things it could be are:

A. Intake Manifold Gasket (wouldn't this be more consistent and heat dependant?)
B. Fuel Injector (My gut is now saying this)
C. IAC (didn't clean this because I cannot get the gasket and o-ring locally and it scares me to reuse the rubber gasket because the coolant lines)
D. Fuel Pump
E. O2 sensor. I've read this is very unlikely

Any thoughts? I'm ready to toss in the towel.+

andrewclaus
Posts: 162
Joined: Tue Oct 03, 2017 6:38 pm
Location: Golden, CO

Re: Random Misfire, Flashing CEL, P0301

Post by andrewclaus » Sat Jul 06, 2019 11:50 am

I'd focus on that one cylinder, rather than general tune-up items. Get new wires. Change fuel injector with another cylinder, see if the code "moves." Do a compression test to rule out an internal mechanical problem.

Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Re: Random Misfire, Flashing CEL, P0301

Post by Browning » Sat Jul 06, 2019 12:44 pm

Since I can't get a fuel injector at my local autoparts stores nor the good intake gasket I decided to check the pcv. It was stuck open and gunked up and while I doubt that is the cause I sprayed it down and soaked it in tb cleaner. It now rattles way better and you can't blow through it.

Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Re: Random Misfire, Flashing CEL, P0301

Post by Browning » Sat Jul 06, 2019 1:33 pm

Ok got the now cleaned up pcv back on. Just took two trips with me pulling over at random spots shutting it down, waiting a couple minutes firing it up and taking off. I drove like a grandma some of the time, other time I got on it a bit. Then I drove in between which is my normal driving. One tiny stumble taking off from a stop sign but no missing, no code or of the recent norm. Coincidence? Maybe but this pcv is definitely getting replaced as I think the spring is a little weak.

I'll be taking it for another drive a little later after I get done smoking some steaks lol

Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Re: Random Misfire, Flashing CEL, P0301

Post by Browning » Sat Jul 06, 2019 3:39 pm

Spoke too soon. It seemed to be running really great. Got 2 miles from home on the last trip and it started again flashing CEL, missing like crazy until we got up to around 30mph. get home, check the light P0301

jolt
Posts: 648
Joined: Sun Mar 02, 2014 2:07 am

Re: Random Misfire, Flashing CEL, P0301

Post by jolt » Sun Jul 07, 2019 2:22 am

Check compression on all cylinders. Swap injectors to see if problem moves. Intake gasket?

Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Re: Random Misfire, Flashing CEL, P0301

Post by Browning » Sun Jul 07, 2019 8:27 am

jolt wrote:
Sun Jul 07, 2019 2:22 am
Check compression on all cylinders. Swap injectors to see if problem moves. Intake gasket?
I don't have access to a compression tester at the moment but today I am going to go ahead and change the intake manifold gasket with the orange one as well as the valve cover gasket. Haven't decided if I just want to knock those out and see what happens or do those and swap in a remanufactured injector at the same time.

I keep trying to find out if when the intake manifold gasket messes up if it's constant or randomly like what I am experiencing. When it isn't doing the missing it runs strong

jolt
Posts: 648
Joined: Sun Mar 02, 2014 2:07 am

Re: Random Misfire, Flashing CEL, P0301

Post by jolt » Sun Jul 07, 2019 4:41 pm

And also OEM or Denso coils. Other brands can give problems and shorter live then the Denso coils. andrewclaus already touched on some of these in his post. Guessing what is the problem can get expensive and new parts can be defective also, so testing to eliminate what is good and finding what is bad is the way to go. Some parts stores have loaner tools, like a compression gauge, that you can rent. Test all the mechanical things first to eliminate them as the problem and then go after the electrical/ECM items (codes).

Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Re: Random Misfire, Flashing CEL, P0301

Post by Browning » Sun Jul 07, 2019 8:12 pm

intake manifold gasket and valve cover gasket replaced(both leaked.) TB gasket too. The problem came back 15 minutes after firing it up. 3 restarts later and it was gone. Drove a few miles and it didn't occur again.

Used a screwdriver to listen to the injectors and 2, 3, and 4 sounds the same. #1 injector is toned different and sounds real clunky. Getting a remanufactured injector tomorrow and if that doesn't cure it, I am just going to suggest to the wife we trade her in. I need a truck anyways lol

Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Re: Random Misfire, Flashing CEL, P0301

Post by Browning » Sun Jul 07, 2019 8:28 pm

Also, while it was missing I went up and was sort of twisting the injector back and forth, lightly tapped on the fuel rail over the #1 injector and unplugged/replugged it and it was the restart after that when it got smooth. However, on that start, I got some white smoke from the exhaust which cleared up on that test drive.

zbyers
Posts: 589
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Location: Sheffield, Pennsylvania

Re: Random Misfire, Flashing CEL, P0301

Post by zbyers » Tue Jul 09, 2019 3:03 am

P0171 = intake manifold gasket, as a general rule of a thumb on theses cars. This is unlikely to cause your misfire.

As others mentioned, Denso ignition coils are usually the go-to. These cars are quite picky.

I'm not sure how difficult the injectors are to remove as I haven't messed with them, but try swapping it to a different cylinder and see if the misfire follows.
(2) '03 Bases, '03 GT, '04 AWD, '06 AWD, '07 Base, '09 AWD
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Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Re: Random Misfire, Flashing CEL, P0301

Post by Browning » Wed Jul 10, 2019 12:50 pm

after putting a reman. injector in there's been no problem. Today is the 3rd day of no issue and hopefully, that fixed it. Had to reuse the old oring as the one that came on the injector was too big and got sliced.

Bookworm
Posts: 233
Joined: Fri Nov 05, 2010 11:21 am
Location: Houston, TX

Re: Random Misfire, Flashing CEL, P0301

Post by Bookworm » Wed Jul 10, 2019 3:02 pm

Browning wrote:
Wed Jul 10, 2019 12:50 pm
after putting a reman. injector in there's been no problem. Today is the 3rd day of no issue and hopefully, that fixed it. Had to reuse the old oring as the one that came on the injector was too big and got sliced.
At least you can order those separately, and you had a functional one to use for now.

Browning
Posts: 35
Joined: Thu Nov 13, 2014 2:06 pm

Re: Random Misfire, Flashing CEL, P0301

Post by Browning » Thu Jul 11, 2019 7:30 pm

Definitely. Car is still running great no missing nor codes. Next to get these motor mount replaced to get rid of that awful idle vibration.

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