I have had a few codes on my 99 corolla. 1 was a o2 sensor problem(fixed w/new sensors). 2) p0300 multi fisfire cylinder 1. I have replaced the spark plugs, and wires. The light is still on and now flashes while driving 55-60mph. My mpg has dropped from 38mpg to 20-25mpg since the light has come on. the car has 235k on the engine and has been well maintained with oil changes every 3k. any ideas what else would cause a p0300 misfire code.
Yes the idle is a little rough. I just came in from cleaning the throttle body and idle controll valve attached the the throttle body. Havent ran the car since.
check your crank sensor and its wire/connector
i found this "Either a bad coil or bad fuel injectors. try switching coils with other cylinder and see if code changes. if yes, you got a bad coil, if not, you must change all 4 injectors, cause they will all go bad eventually."
Last edited by Fergifruitchew; 08-25-2009 at 09:43 PM.
I also get the flashing CEL... My cylinder1 and cyinder4 are crap. I had the "random misfire code" plus the "cyl 4 misfire code." My 1 and 4 have little to no compression because the valves are shot. My car is running rough at idle and starts hard because I'm basically running on 2.5 cylinders...
This may or may not be your case, but you'll know immediately after a compression test.
try to see if the coilpack is gone for starters, you said you have problems on cylinders 1 and 4? the first coilpack fires for 1 and 4, if you look at the numbers on both coil packs they read
|1 4| |1 4|
|3 2| |3 2|
what you should do it switch the two, unplug the wire harness and plug it into the other one, and switch the spark plug wires, then start it up and see if you now have problems on cylinders 2 and 3. just to get that test out of the way.
do a compression test, how did the valves get shot?
chevy mechanic, cool, im putting a 305 in my 92 toyota pickup. lol
Last edited by Fergifruitchew; 08-25-2009 at 10:17 PM.
try to see if the coilpack is gone for starters, you said you have problems on cylinders 1 and 4? the first coilpack fires for 1 and 4, if you look at the numbers on both coil packs they read
|1 4| |1 4|
|3 2| |3 2|
what you should do it switch the two, unplug the wire harness and plug it into the other one, and switch the spark plug wires, then start it up and see if you now have problems on cylinders 2 and 3. just to get that test out of the way.
do a compression test, how did the valves get shot?
chevy mechanic, cool, im putting a 305 in my 92 toyota pickup. lol
Yea I put in a bored out 454 in my 71 elcamino and cant seem to keep tires on it
try to see if the coilpack is gone for starters...
do a compression test, how did the valves get shot?
(I'll reply to the post in hope to help the original poster)
I'm one step ahead, because I...
swapped coils, no change
swapped injectors, no change
new iridium plugs, no change
checked valve clearance, all good
checked compression, ack... problems.
Used seafoam directly in pistons and in vacuum line with no change.
To quote Mission Impossible 1, "That's the question I want to ask Job" err Toyota. How did it become that I have 80lbs compression in cyl3 and 0lbs in cyl4... Needless to say, I will be pulling the head this week.
Coclusion to the p0300 multiple mis fire code. Replaced plugs, wires, coils, and crankshaft position sensor. Still the check engine light was on. Disconected the #1 fuel injector wire harness the engine ran the same. The #1 fuel injector was bad. I got 4 good fuel injectors with 31k miles off ebay for $40 and the problem is fixed. The last thing that I was going to check was the problem. Spent $1,000 trying to fix a mis fire problem and it ended up to be the fuel injector.
Did a Google search and found that I have the exact same problems as you (except I have checked the wires and one plug looks fine). Codes - P0301 P0304 P0300 My only remedial action so far was to dump some Techron in the tank to see if it's a dirty injector. But, we have the same model, mileage and problem.
I'm dealing with the same issue, has anyone found a "smoking gun" for this that isn't beat down cylinders, I've completed evrything mentioned in this thread, but I don't have a compression check gauge, so I'm stumped as to what could be keeping my #4 cylinder from firing...
I had those codes in our 99VE and it turned out to be fouled spark plugs. I replaced the ones in it with Bosch Platinum plugs and not the Iridiums andthat might have been some of the problem despite them lasting like 2-3 years. One plug was way sooty and another was way lean while 2/3 were normal. Thought about replacing the 1/4 coilpack, but that didn't make any difference in the way it ran or the blinking CEL. I replaced the OEM(11yr. old) plug wires despite their resistance values checking out fine, those bench tests don't show what they do under load. I'm still not getting the mileage I'd like to, but not getting O2 sensor codes, so something else might be the problem. Maybe just wait for spring when I can get outside with it. I get real bitchy with cold hands.......
DM&FS
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Hi, I am new to this site, I am a cruiser fan but my girlfriend has a corrola. She had cel go off for multiple misfires. Replaced plugs, cel is back, she brought it to VIP and they ran diagnostic, they said #1 cylinder was off by 25.
So I need to check injectors, coils and all associated wiring first. It could be one those things?
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