HawkGT

I've done a search on a P0300 code but none of the threads seemed to fit my scenario.

On my drive home last night my fuel gauge was on "E", literally, so I pulled over at a very busy Raceway gas station and filled up. About 20 miles later my motor started missing a little. This morning when I left the house I noticed it was idling rough. Within 2-3 miles it was running VERY rough and backfiring/popping in the airbox. After a few minutes of this the CEL started flashing. I took it straight to my local Autozone and pulled the codes. I had a:

P0300 Random/Multiple cylinder misfire
P0301 Cylinder 1 misfire
P0302 Cylinder 2 misfire
P0305 Cylinder 5 misfire
P0107 Right bank too lean (pre-existing condition)

I told the guy at Autozone the codes and asked his opinion on the issue being bad gas since I filled up right before this started. He said "yes, multiple cylinder misfire is the common code for bad gas". He sold me some Heet and octane 104 and suggested that I drive it.

I have been driving around most of the day, with the CEL occasionally blinking, and the condition is no better. I have burned off around a half tank of gas and refilled with 93 octane fuel, but the condition is no better. It acts like it is loading up and then if I open the throttle a little then it cleans out a bit but then starts loading up again.

From reading the forum I have found that this problem has been caused by bad coil packs, plugs, and wires, but this doesn't seem probable in my case because more than one pair of cylinders is misfiring at the same time. I also speculated that the low fuel level caused me to pick up some sediment in the tank which clogged the fuel filter, but this would cause a lean condition not a rich (loading up) condition. I went ahead and bought a fuel filter since the truck has 104k miles and I haven't changed it in the 60k I have owned it but no improvement in idle. Any other suggestions?

1989toy4wd

Oxygen sensor maybe, I when I first read it, I though it was cyl 1 3 5, but I read it again. its probably a sensor, oh and by the way any octane booster stuff doesnt work. It raises the octane alright, but only by .2!!

1989toy4wd

There is no way that many coil packs went out at once, i mean its possible, but not very likely, could be a clogged fuel filter too!!

HawkGT

Yep, I went ahead and changed out the fuel filter today because of the age if nothing else. It didn't help with this issue, even though I'm sure it probably needed to be changed anyways.

97ltd4x4

I would pull and inspect the plugs,possible something happened to dump too much fuel into the system and foulded them...also check crank pulley bolt.

You did not by chance clean the enginge bay?

ravencrew

What is your top speed? Are you able to get up to Highway speeds? It sounds like you might have a Timing Issue. Have you checked your radiator levels? You could have the same problems I had. I changed the fuel filter, plugs,wires, MAF, TPS and it ended up being a bad water pump dumping coolant on my timing belt which caused it to slip and threw the whole truck out of time.
Here is the link:
https://www.yotatech.com/forums/f2/n...lp-one-162195/

HawkGT

Nope, haven't cleaned the engine bay in quite some time. I will pull the spark plugs this morning and check them out.

I was able to get up to highway (approx. 80mph) yesterday, however on hills it would start popping/back firing in the air box. I replaced the timing belt and water pump about 10k miles ago. I looked all around the engine bay and didn't see any wet spots. I could check under the upper timing belt cover to see if anything looks amiss.

I'm definitely not interested in throwing money at parts to solve this. It sounds like I'm getting close to making a trip to the dealer.

BigBallsMcFalls

fuel system flush from fuel rail to tank....sounds like crap in fuel really

97ltd4x4

Normally If you had posted with a p0300(random miss),p0302,p0305..I would have said rear coil#5 is going bad since both cylinders are sahred by the same coil...BUT..With the backfiring going on I would inspect the t-belt alignment,cam sensors and crank sensor..not if they are bad,but if they are loose,or a cam gear is loose,crank pulley is loose...That is how the ECM determines timing by looking at crank=rpm,cam=position of cams(calculates piston position) so then the ECM can turn on and off the coils=Ignition Timing.

I only mention this because usually p0300x codes make a miss,slight or otherwise,no backfires.....I still think its good form to inspect the plugs anyway for clues,along with timing componants..

And to avoid confusion about the wire#s and coils:
Coil:goes to cylinder:
#1 goes to #4
#3 goes to #6
#5 goes to #2

DeathCougar

iTrader: (23)

I would take it to a shop, before you lean your motor out and destroy it.

HawkGT

I pulled all of the spark plugs. Cylinder 1,3,4,5, and 6 were all a reddish/rust color. I have never seen anything like this but I read a few posts and apparently this is common and due to fuel additives. Since I recently put in a bottle of Heet and Octane 104, I'm guessing it is from one the the two. Other than the red color the electrode and insulators were in good shape.

Cylinder 2 appeared to be running very rich.

I pulled the cover off the timing belt and it appears as though the cam gears and crank are all aligned. It also appeared that the crank bolt and timing sensor were tight.

I guess I will drop my truck off at the dealer tomorrow morning.

HawkGT

To follow up on my initial post I thought I would provide the results from taking my 4runner to the stealership. The truck is running well now, it just tears me up knowing how much they charge for things I could do if I knew that was the problem.

There were two problems. I had a bad MAF sensor which was causing the lean condition across all the cylinders. I also had a dead cylinder #2 which was fixed with new plugs and wires. I also had an fuel system/injector cleaning run but this was for efficiency and smooth operation as much as anything. Thanks for all of the sugestions from the forums. Thanks!

Godzilla

Glad its fixed, and good job on the update. Its pretty funny how a few small things can cause such a ruckus.