P0300 - Multiple cylinder misfire

[bluepants42]

Greetings, [IMG]file:///C:/DOCUME%7E1/TINALI%7E1/LOCALS%7E1/Temp/msohtml1/01/clip_image001.gif[/IMG]

Car: 2000 corolla
Problem: Car hesitatates during acceleration, cannot really go above 30 mph..almost wants to stall if press on gas too hard

After using the code reader, i've found P0300 and P0301 - (random/multiple misfirings and cylinder 1 misfire.) There were no other codes. From what I can tell, most people change the spark plugs.

Work done: Changed spark plugs, did not change ignition coils (to save $). The spark plugs had motor oil on the threads which was somewhat concerning....

Question: Any ideas on where to go from here? I don't want to just buy random parts and try to fix the problem....w/o knowiing for sure it is going to work....considering taking it in for engine diagnostic
some say O2 sensor...

thanks

[bluepants42]

In addition: In the past there was a p0171 code but has "disappeared" after a friend took the battery cables off to "reset".

Going to try to clean the MAF and see what happens.

[stubborn1]

Last time I had the P30x code, it was a bad spark plug wire. I wouldn't change the coils yet. If you suspect the coils, reverse the positions of the two coils and see if the misfire moves to a different cylinder. The 2000 still has two coils right?

[REN69]

I'd say wires too or either the cap is cracked or lose, check those things out. Open your hood in a dark area and see if the wires are grounding somewhere when the car is on, you will see a spark jumping from the wire to anything nearby that is metal.

[retiredat44]

Originally Posted by REN69

I'd say wires too or either the cap is cracked or lose, check those things out. Open your hood in a dark area and see if the wires are grounding somewhere when the car is on, you will see a spark jumping from the wire to anything nearby that is metal.

the spark jumping in the dark sign, of bad wires, is not always telltale. I say go with mileage and age on the wires and cap. If they have more than 50,000 miles on them, and also what quality are they, get some with a lifetime warranty, or at least a 2 year warranty.

IMHO

[bluepants42]

Originally Posted by stubborn1

Last time I had the P30x code, it was a bad spark plug wire. I wouldn't change the coils yet. If you suspect the coils, reverse the positions of the two coils and see if the misfire moves to a different cylinder. The 2000 still has two coils right?

Two coils? I might be misunderstanding, but one ignition coil per spark plug? After cleaning the MAF...a little better. But from a stop still pretty slow acceleration and poor acceleration when stepping down on pedal. Thanks for the tips...i'll update you guys when i find out more...prolly going to take it in tomorrow.

thanks

[stubborn1]

Originally Posted by bluepants42

Two coils? I might be misunderstanding, but one ignition coil per spark plug? After cleaning the MAF...a little better. But from a stop still pretty slow acceleration and poor acceleration when stepping down on pedal. Thanks for the tips...i'll update you guys when i find out more...prolly going to take it in tomorrow.

thanks

On my 98, I have two coils. One controls firing for cylinders 1&3, the other for 2&4. I looked into it a little further, and 2000 setup is different so my comment doesn't apply exactly. The point I was trying to make is swap around ignition components and see if your P301 code moves to a different cylinder. If you swap components and it moves, you know you found the bad component.

[bluepants42]

In closing, took it into pepboys.

Code: P0171
Their Fix: clean MAF sensor, used some sort of fuel injector cleaner, "gum-out", and Lastly and most importantly their "4-step cleaning"

Comment: it did fix the problem, car runs smoothly with no hesitation. They said there was "too much carbon in the system" and they used a product called "run-right" with the 4-step cleaning. they said it wasn't available to the public.

In closing: I like to usually to fix my car on my own, but I agree with one person who said always to make sure to part is broken before replacing it. I get into the habit of wanting to troubleshoot on my own by replacing parts. There were various reasons that these codes/symptoms were happening, i didn't have the time/money to explore all of them. Sometimes it is cheaper/faster to just bring it in.



i just wanted to close with thread with the conclusion. thanks for everything

[retiredat44]

I never had a car with a MAF sensor problem, so I guess it is one more experience with these Toyotas I never experienced.. it looks like lot of people get screwed by this snesor by the amount of forum posts about this part failing.