I have a 2003 corolla with 235,000 miles. Recently, the car has started to misfire when cold. After it completely warms up, the car runs perfectly. The CE code is showing cylinder 2 & 3 misfire. I initially suspected the coil blocks so I switched around 2 & 3 with 1 & 4 but it is still having the same problem (with same code). The plugs are fairly new. Additionally, the fuel pressure has been tested and is good so the only other ideas that I have are bad fuel injector(s) or leaky intake manifold. I ran some seafoam in the gas but that did not help at all either. What are the best ways to check for a fuel injector problem or a leaking intake manifold? Any insight would be greatly appreciated.
Welcome, that is a lot miles! Any oil on the plugs? An used oil analysis would show a fuel injector leak, only costs $24. This will also look at a possible coolant leak, which can also cause your problem. How is your coolant level?
What plugs are you using? Denso or NGK iridium should only be used. They come pre gapped. Did this issue only happen after you put in the new plugs? If so, get new plugs in there.
To test the intake manifold, spray carb cleaner around the manifold when the car is running, and listen if the engine surges.
What kind of air filter do you have? If you have an oiled air filter, you may have a contaminated MAF. It is easy to check, just remove two screws and a plug and look to see if the MAF wire is dirty.
Gumout regane and Redline Sl-1 are pretty good cleaners, might want to try them.
Thanks for the info Mike! I have always used NGK plugs and the current set has been in there for about 20,000 miles. The air filter is a stock type. However, I will check the MAF, air filter and plugs for oil. I will also try testing the intake manifold as well. It may take me a day or two but I will let you know what I find out.
Thanks for the info Mike! I have always used NGK plugs and the current set has been in there for about 20,000 miles. The air filter is a stock type. However, I will check the MAF, air filter and plugs for oil. I will also try testing the intake manifold as well. It may take me a day or two but I will let you know what I find out.
If all of that does not work, might want to just to put in brand new plugs and if that does not work, an UOA may be in your future.
I tried spraying some carb cleaner around the intake and the engine didn't seem to have any reaction. Even though I'm using a stock air filter, I also checked the MAF sensor and that looked OK too. I guess the next step will be swapping the plugs and trying the products that you recommended. Where exactly can one get the engine oil analyzed?
I tried spraying some carb cleaner around the intake and the engine didn't seem to have any reaction. Even though I'm using a stock air filter, I also checked the MAF sensor and that looked OK too. I guess the next step will be swapping the plugs and trying the products that you recommended. Where exactly can one get the engine oil analyzed?
You can get gumout regane at walmart and Redline Sl-1 at pepboys. Make sure it is regane (clear bottle, yellow product), not any of gumout's products. I think regane is $5 and Redline is $9.
That site does analyses, I used them and no problems. That link describes everything about your sample.
The test kit is free, so I would order it now. Hopefully you are far into your oil change. As you are draining your hot oil, grab a sample mid stream and fill the plastic container and send it in with the check, if you are curious about how your oil is holding up and are near the end of your oil change, ask for TBN, it costs $10 more but can be helpful about how much longer you can run your oil, if you care about stuff like that. In your case it is very important to grab a hot sample, not cold.
As you can see, it lists fuel and antifreeze along with many other items. What you see is what you get, only a few comments from Blackstone, certainly not an in depth interpretation, if you want that, you have to pay big bucks. You can post it on that site and ask for free feedback.
Hopefully it wont get to that point and it is just something simple like new plugs. If in doubt just replace them, you can only check the gap on iridium tipped plugs, not adjust them (well you can but it can be difficult) When you are draining the oil, you will get sense if there is gas in the oil, you will smell it in the drain pan.
How is your oil level and how is your mileage? Did you clear the code after you swapped the coil plugs?
Last edited by mikered30; 03-28-2010 at 08:45 PM.
Reason: added link
Don't know why I did not remember this before but a cheaper (free) way to check for leaky injectors is to remove the fuel rail then reconnect the fuel lines and turn the key to on then off then on, fuel should not come out of the injectors. Injectors can crack along with the o rings. But you said the fuel pressure test was ok, so it does not seem likely that it is a leaky injector, all signs point to spark plugs.
I was able to throw a new set of plugs in yesterday. Since then, I have driven it twice and things seems to be OK. The plugs didn't seem to be all that bad and they had been in there for only 28,000 miles. The only thing that jumps out at me is the fact that I did purchase the bottom of the barrel NGK's last time around. This time I stepped up to the plate and purchased the platinum variety for $2.99 each . It has been much warmer here lately so we shall see if that is a factor or if there is another underlying issue contributing to the misfiring. I would feel pretty silly if it was something so simple...but so far am feeling fortunate that she is running great again. Updates will follow. Thanks again for the help.
I was able to throw a new set of plugs in yesterday. Since then, I have driven it twice and things seems to be OK. The plugs didn't seem to be all that bad and they had been in there for only 28,000 miles. The only thing that jumps out at me is the fact that I did purchase the bottom of the barrel NGK's last time around. This time I stepped up to the plate and purchased the platinum variety for $2.99 each . It has been much warmer here lately so we shall see if that is a factor or if there is another underlying issue contributing to the misfiring. I would feel pretty silly if it was something so simple...but so far am feeling fortunate that she is running great again. Updates will follow. Thanks again for the help.
Good to know, but the plugs should be iridium, about $8 each. Were the NGKs you pulled copper or platinum?
Hi Mike. The NGK's I pulled were the standard BKR5ES. They are probably tipped with chinese coal ash . I put in the G-Power Single Platinum BKR5EGP which probably aren't much better. Wasn't aware that the iridium is that critical. That is good to know. The original plugs were changed at probably around 90,000 miles and I have replaced them approximately every 50,000 miles thereafter.
Hi Mike. The NGK's I pulled were the standard BKR5ES. They are probably tipped with chinese coal ash . I put in the G-Power Single Platinum BKR5EGP which probably aren't much better. Wasn't aware that the iridium is that critical. That is good to know. The original plugs were changed at probably around 90,000 miles and I have replaced them approximately every 50,000 miles thereafter.
The manual (Toyota) says that iridium plugs should be used. They come pregapped. They are good for 100,000 miles.
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. It has been much warmer here lately so we shall see if that is a factor or if there is another underlying issue contributing to the misfiring. I would feel pretty silly if it was something so simple...but so far am feeling fortunate that she is running great again. Updates will follow. Thanks again for the help.
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