toyota corolla 2003 check engine light P0301

[Jeroen]

Hey Guys,

I’m looking into a check engine light P0301 (misfire cylinder 1) on my toyota corolla (2003). (it’s a 1600cc VVTi engine with only 27000 kilometers on it (about 17000 of 18000 miles))

****short version*****
already replaced plugs and air filter
cleaned maf sensor and throttle body
****end of short version*****

*****long version***** 🙂

I started using this car about a year ago at which point it had been sitting for 2 years. (it belonged to the deceased father of my girlfriend) When i took it into use i brought it to a toyota dealer and explained that it has been sitting for 2 years and asked for advice what service was needed. They suggested to do a oil change and take it to the mandatory inspection. It passed the inspection. I also inquired about the old fuel still left in the tank (2/3 full). They said that i could just use this fuel without a problem. (i was more inclined to remove it and fill her up with new fuel but since i couldn’t get it out in a simple way i stuck with the dealers advice and used up the old fuel.

So from that point on i used the car from time to time. (i only did 1700 miles with it this last year) I always seemed to have a bit af a rough idle where it sometimes dipped a bit low and appeared to be on the brink of stalling. I first thought i might be the old degraded fuel. But after 1 or 2 fill-ups it still remained. Since i didn’t use it alot and it never actually stalled i got used to it a bit. Then after 4 months of using it i noticed a performance issue (loss of torque and rough running of the engine) After a short while i got a check engine light. I took it to the dealer to have it checked (unfortunately i didn’t read the code myself) and they replaced the sparkplugs and reset the check engine light. This solved the performance issue but the rough idle still was there (although it seemed to be a bit better then before). Since it was not completely solved it took a look myself and saw that the air filter was a bit dirty (looked quite grey/black and contained some debris of fallen tree-leaves) so i decided to replace it since it wasn’t expensive and a clean air-filter is always a good idea 🙂 At that time i also checked the maf-sensor (sprayed it with some compressed air to clean it (the parts store here didn’t have any maf-sensor-cleaner at that time) and some contact-spray on the electrical connections for good conductivity. Lastly I cleaned the throttle-body with some throttle-cleaner. That seemed to improve the situation with the idle (or it could be just in my mind 😉 but it still wasn’t gone completely. But since I thought it was better i decided to give it some time. Last week i got a check engine light again. I usually only do short trips with this car but that time i had done a 30 minutes highway drive (so the engine was well warmed up). When coming from the highway i was waiting on a slight uphill and there it hiccuped again very noticeably but without stalling only to flash the check engine light a bit further down the road for a few seconds and then having it constantly lit. Strangely enough the light went off on the next ride. But a few days later it was back. (flashing a few seconds and staying on and this time also on the next rides) Yesterday i got out a laptop and odbII-cable and it was a P0301 (cylinder 1 misfire detected).

******end of long version*****

After reviewing lots of information on this and other websites i decided that this weekend i will check for vacuum-leaks as a next step(already watched the videos by eric). (and also maybe check the ignition: plugs, cables (but i suspect they would have already looked into that at the dealer when they changed the plugs some months ago)

What do you guys think? Good idea? Or should i look into other things first? Or does anyone have some pointers/experience on this type of engine?

Thanks in advance

Greetings

Jeroen

ps: i’ll hopefully get back with more findings after the weekend. (just wanted to see if i can check other stuff as well while i’m in there;)

Topic

[EricTheCarGuy]

I don’t think that was an oil leak. From what I’ve seen that’s fairly typical of a coil failure like the one you had. I’d replace the coil and then recheck to see if you continue to have that issue. Keep us posted.

[Jeroen]

Hi Eric,

I replaced the coil (as well as the gasket) and the engine seems to be running fine since then.

The new gasket didn’t cost that much so i thought it would be better to be on the save side and not have another coil go bad. (the old gasket stayed nicely locked into the valve cover in all but one place when i removed it… it only sprung out on cylinder 1. (it was still nicely bendable so it might just have been not sitting right at cylinder nr 1)

Anyway: The engine now runs nicely so i think as far as the check engine light goes it should be fixed now 🙂

Again thanks to all of you who pitched in 🙂

Greetz

Perre

[EricTheCarGuy]

Glad you got it sorted out. Thanks for keeping us up to date and for using the ETCG forum.

[Author]

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