Help with CEL codes...all kinds of misfires.

[FanOfSkynyrd]

Ok, new member here, been reading through the forums in the past for various things. Now I've run into a roadblock and need some assistance.

It all started when I tried out a bottle of A/C Pro. I live in the Arizona desert, and although the air was blowing cool I thought it could use a boost. Well that turned into a disaster as it did more harm than good. After getting the system serviced (should have done that in the first place) all was good.

We drove out to San Diego and back for a quick summer vacation...all was fine for about a week. I then noticed a rough idle when parked...even more so with the air on, so I thought...oh no, compressor. I took it back to were I got the ac serviced, tech said everything on the ac side checking out good, pressure was good, no leaks, compressor not binding up. He then plugged an OBD scanner in cause the cel was flashing and he asked when the last time I had a tune up. It showed showed p0300, p0301, p0303, p0305, and p0307.

I went ahead a replaced the spark plugs myself yesterday (NGK Laser iridiums). Plugs in there were all Denso's and some looked pretty bad.

Took me about 1.5 hours and after everything fired up like it should. However, after it idles for about 10 minutes I get the following codes: p0300, and p0301-0308...so now saying misfiring on all cylinders.

Any thoughts in what my next steps should be? I'm thinking of cleaning the TB and MAF...but what else could be...the coils, pcv...or something else. Timing belt was changed 40k miles ago.

It's a 2003 sr5 v8 and has about 145k miles on it.

Many thanks in advance.

 

[2007toyota4runners]

i replaced my plugs and got a misfire on 5 and 6 and then just ended up getting it towed to the dealer turns out i got some cracked plugs from the dealer hope you get this straightened out

 

[ChaosStarter]

Make sure those plugs are the same heat range as the OEM denso's. I've seen a lot of people recently going elsewhere and buying anything that says Iridium since that's what the motor calls for, but they don't check to see if they're the same heat range.

I had an '04 Camry 4cyl come in with multiple misfires this week. Good fuel, good spark, good oil. Pepboys charged her for all 4 coils and new plugs. Guess what? Still had misfire codes. She originally had a neighbor replace the original plugs which is when the mess all started.

I told her, I can't do anything about the coils but I can try the OEM denso's and go from there as I didn't think the coils were to blame. Put in the Denso's and what do you know...no more misfires. I had her leave the car and put another 40+ miles on it without the misfires returning, when she said that they would be there right away, morning or night, hot or cold engine. Pepboys put in NGK iridiums but if you do a cross reference on the plugs, they never match up what so ever. The plugs in the Camry call for Denso SK20Rs, which are the same that our 05+ V8's call for. She had NGK BKR6IEX-11's from Pepboys. It's weird, but you have to consider these things.



Does the truck make good power? Or are the misfires very obvious?


*Edit* Toyota does call for NGK's and Denso's for use in vehicles, I just wanted to make sure these particular NGKs were not the equivalent to the OEM NGK's.

 

[FanOfSkynyrd]

Thanks for the replies thus far. The engine runs strong...its only when sitting at idle in park...and it usually takes about 10 minutes of idling in park that the cel starts flashing. It only flashes, never goes solid lit. As soon as I out her in gear and start driving cel stops flashing.

Before swapping out the plugs you could feel a noticeable vibration from engine at idle...since swapping the plugs engine feels considerably smoother at idle, still vibrates just not near as bad as before the plug swap. Under all other driving conditions engine is smooth as butter.

I'll try to dig up thepart number for the plugs I used but I did a lot if research on the plugs and the ones I got seemed the second runner up compared to the densos.
,
**edit** I used the ngk ifr6t11, no place locally sells the densos.

 

[BOSMECH]

Lets start by checking for a vaccumm hose leak first.
Go back over all the work that has been done before it started running bad.

 

[ChaosStarter]

Lets start by checking for a vaccumm hose leak first.
Go back over all the work that has been done before it started running bad.

Like he said, check for that PCV hose if you removed and any lines connected to the airbox.

 

[FanOfSkynyrd]

Vacuum lines was going to be my next step but first I swung by the parts store picked up a new pcv valve. Swapped it out, old one was pretty nasty.

Let it idle for 15 minutes with ac on high...no cel. Did a fair amount of driving with 2 stops idling for roughly 10-15 minutes each...no cel.

I think the pcv valve did the trick. In my internet research I stumbled on the below website...a lot of good info on misfire codes/diagnosis.

Random-Misfire Page

I will follow this with an oil change today, and plan for a new fuel filter in the coming months.

I follow up with an update post in a couple of weeks to let you all know how she's running.

 

[aha2988]

heres your answer buddy:

what do 301, 303, 305, 307 have in common.. all those cylinders valves run off the same cam shaft.

what controls the cam shaft... The timing belt..

your timing belt has slipped and now your valve timing is off enough to where when the spark plug fires theres actually not any gas in the cylinder yet to ignite.

ITS THE TIMING BELT..

heres my story: http://www.toyota-4runner.org/4th-g...8-rough-idle-misfiring-p0300-p0301-p0308.html

 

[aha2988]

also when your CEL starts FLASHING AT YOU that means it wants your attention badly because your in risk of destroying your engine..

The CEL is flashing because without those cylinders firing your pumping pure gas into the exhaust CAT's.

The exhaust cats are design to burn off excess gasses and emissions. when they get to much of those gasses over a small period of time.. you'll see your catalytic converters catch on fire!

that flashing CEL light is telling you that the o2 sensors are ready extremely dangerous numbers!

 

[aha2988]

you may have changed the timing belt 40,000 miles ago but if you took it to a dealer, I'm just assuming they only changed the belt. Not the water pump, idler tensioner pully, auto tensioner, or any of the other various componants that make up the timing belt assembly..

I'm betting your water pump has developed a leak under the factory gasket alowing coolant to drip onto your timing belt. when the belt gets wet there has been cases of this causing the belt to slip a tooth or two over the crankshaft pully causing the bad timing.