backstory:
a few years ago, car began to idle roughly and misfire under load at freeway speeds (hence the p0300). finally took it to the dealer. they replaced the pcv valve, that fixed it for a day or two, then the issue came back...took it back to dealer (I never use the dealer, but had recently moved to Houston and was not aware of any other decent mechanics at the time). Dealer scoped the cylinders, tested compression, found nothing. their advice: buy a new engine. well....no thanks.
I had read that sometimes oil can get into the cylinder and while not affecting compression, can interfere with combustion, and since my issue was just cylinder 3, that could be it...not a bad piston ring, but some sort of oil either staining the cylinder wall or something along those lines...so I put about 1/4 of a can of seafoam into the crankcase...seemed to help a bit for a short time, CEL went away....then a few weeks later it came back, along with the misfires.
Idling with the a/c on was just downright annoying. during this time, I thought maybe it was a clogged injector, since it would misfire at high speeds under load, so I ran some lucas injector cleaner in the fuel for a while...nothing....ran the STP stuff that is in the seafoam like cans a few times....nothing...ran a few cans of seafoam for a while...nothing.
Being stubborn, and not willing to give up, 2 weeks ago I searched google for "best injector cleaners" since I really felt my situation was in that realm...there were a few good write ups on many I had never heard of. So I double checked my research with checking Amazon and their customer reviews for these products...I ended up going with LubriMoly injector cleaner. write ups were very positive.
So, get the stuff a few days later, dump it in the tank...nothing...well, I had not started my engine, yet, so figured I should give it some time...100 miles later, cel turns off...OK! nice...let's get it under load on the freeway...much, much improved, but still a few misfires in there. at idle with the a/c on, it is vastly improved, but still not entirely fixed. So, ran a tank of that and had then bought the LubriMoly valve cleaner. No idea if this is different than injector cleaner, but figured for around $8 I should give it a try. added that to my next fill up a few days ago. after a few days, could not really see any improvement.
so, yesterday, I finally decide to seafoam my intake. by this, of course, I mean let the brake booster suck some seafoam. drive the car a bit to get up to operating temps, pop the hood, add seafoam to a small cup (so i can see how much it is taking) and with the engine idling, remove the booster line and let it suck up the seafoam. i then hustle over to turn the engine off (i could not get it to stall). after about an hour, I have to leave to go get my son for swim practice, go to start the car, and it does not start right up. I figured this is good since that means there is seafoam still in there...second try, car starts right up. no smoke, nothing. begin driving...ahhhh, there is the smoke! under load, the car is emitting the tell tale smoke screen of a recent seafoam job!
In not too long of a time (about a mile of lots of stopsigns, so I get to accelerate quite a bit) the smoke is gone. next stop sign, I sit and wait....idle is perfect...and then drive...next stop sign...idle still perfect. get the kid and drive to swim practice, about 4-5 more stop signs...idle is perfect at each on, and not a single misfire while under load at 35+ mph. drive home, same thing.
so it has been a day, car still idles perfectly and have not seen a single misfire. I believe my issue is fixed. so, I have no idea what the actual issue was. I will admit, for years we ran Costco and Sam's club and Arco fuels since they were quite a bit cheaper in Seattle than others...could that have really dirtied up the valves and injectors? probably. This was the wife's car, so not like she was adding any additives on her own and such.
In the end, I'd say about $100 in various "cleaners" spent over a year, not a new engine (quoted $5800 all in including install), but this probably could have been solved with less than $25 with the Lubrimoly stuff and the seafoam in the brake booster line. In Houston, Shell and Chevron are super inexpensive so that is what we run now, so hopefully the issue is solved permanently.
I wanted to put this up to the group for a few reasons. They are:
1. I had read a few people having this same issue and spent quite a bit of $ on hardware that had not fixed it.
2. I am a huge skeptic when it comes to fuel and oil additives. I figure they can't hurt much, but do they really do anything? In this case, the lubrimoly injector cleaner definitely did something (and the Amazon reviews say the same thing). And the seafoam through the brake booster definitely did something. I am still a bit amazed at how nicely this has turned out. granted, only a day, but the idle is literally perfect with the a/c on now (was always smooth with it off).
a few years ago, car began to idle roughly and misfire under load at freeway speeds (hence the p0300). finally took it to the dealer. they replaced the pcv valve, that fixed it for a day or two, then the issue came back...took it back to dealer (I never use the dealer, but had recently moved to Houston and was not aware of any other decent mechanics at the time). Dealer scoped the cylinders, tested compression, found nothing. their advice: buy a new engine. well....no thanks.
I had read that sometimes oil can get into the cylinder and while not affecting compression, can interfere with combustion, and since my issue was just cylinder 3, that could be it...not a bad piston ring, but some sort of oil either staining the cylinder wall or something along those lines...so I put about 1/4 of a can of seafoam into the crankcase...seemed to help a bit for a short time, CEL went away....then a few weeks later it came back, along with the misfires.
Idling with the a/c on was just downright annoying. during this time, I thought maybe it was a clogged injector, since it would misfire at high speeds under load, so I ran some lucas injector cleaner in the fuel for a while...nothing....ran the STP stuff that is in the seafoam like cans a few times....nothing...ran a few cans of seafoam for a while...nothing.
Being stubborn, and not willing to give up, 2 weeks ago I searched google for "best injector cleaners" since I really felt my situation was in that realm...there were a few good write ups on many I had never heard of. So I double checked my research with checking Amazon and their customer reviews for these products...I ended up going with LubriMoly injector cleaner. write ups were very positive.
So, get the stuff a few days later, dump it in the tank...nothing...well, I had not started my engine, yet, so figured I should give it some time...100 miles later, cel turns off...OK! nice...let's get it under load on the freeway...much, much improved, but still a few misfires in there. at idle with the a/c on, it is vastly improved, but still not entirely fixed. So, ran a tank of that and had then bought the LubriMoly valve cleaner. No idea if this is different than injector cleaner, but figured for around $8 I should give it a try. added that to my next fill up a few days ago. after a few days, could not really see any improvement.
so, yesterday, I finally decide to seafoam my intake. by this, of course, I mean let the brake booster suck some seafoam. drive the car a bit to get up to operating temps, pop the hood, add seafoam to a small cup (so i can see how much it is taking) and with the engine idling, remove the booster line and let it suck up the seafoam. i then hustle over to turn the engine off (i could not get it to stall). after about an hour, I have to leave to go get my son for swim practice, go to start the car, and it does not start right up. I figured this is good since that means there is seafoam still in there...second try, car starts right up. no smoke, nothing. begin driving...ahhhh, there is the smoke! under load, the car is emitting the tell tale smoke screen of a recent seafoam job!
In not too long of a time (about a mile of lots of stopsigns, so I get to accelerate quite a bit) the smoke is gone. next stop sign, I sit and wait....idle is perfect...and then drive...next stop sign...idle still perfect. get the kid and drive to swim practice, about 4-5 more stop signs...idle is perfect at each on, and not a single misfire while under load at 35+ mph. drive home, same thing.
so it has been a day, car still idles perfectly and have not seen a single misfire. I believe my issue is fixed. so, I have no idea what the actual issue was. I will admit, for years we ran Costco and Sam's club and Arco fuels since they were quite a bit cheaper in Seattle than others...could that have really dirtied up the valves and injectors? probably. This was the wife's car, so not like she was adding any additives on her own and such.
In the end, I'd say about $100 in various "cleaners" spent over a year, not a new engine (quoted $5800 all in including install), but this probably could have been solved with less than $25 with the Lubrimoly stuff and the seafoam in the brake booster line. In Houston, Shell and Chevron are super inexpensive so that is what we run now, so hopefully the issue is solved permanently.
I wanted to put this up to the group for a few reasons. They are:
1. I had read a few people having this same issue and spent quite a bit of $ on hardware that had not fixed it.
2. I am a huge skeptic when it comes to fuel and oil additives. I figure they can't hurt much, but do they really do anything? In this case, the lubrimoly injector cleaner definitely did something (and the Amazon reviews say the same thing). And the seafoam through the brake booster definitely did something. I am still a bit amazed at how nicely this has turned out. granted, only a day, but the idle is literally perfect with the a/c on now (was always smooth with it off).
