2000 4.7 multiple cylinder misfire

Hello all!

I have a 2000 4.7 liter tundra with 208,xxx miles. I bought it a few months back and haven't had any problems with it until now. 2 weeks ago I was driving down the highway when Noticed misfiring, loss of power and a flashing check engine light. Took it home and ran the codes, p0305 and p0155. I read online that the number one cause of misfires was bad ignition coils so I order a whole set and replaced them. the truck ran fine for a week and then the same thing happened. ran the codes again, p0155, p0300, p0303, p0305 and p0307. after this I replaced all the the spark plugs with denso's, cleaned the intake, checked the intake for leaks, cleaned the mass air sensor, and ran seafoam through the fuel system. And still have the same missfiring, codes, and low idle. I called my nearest toyota dealer and they quoted the repair at atleast $1000 dollars... My next idea is changing the crank shaft position sensor, replacing the o2 sensor, or digging into the timing belt. Is it possible that the o2 sensor could be causing a multiple cylinder misfire? Is it likely a timing issue? What should I try next? Please help! Also the truck has idled at about 600 rpms since I've had it and now idles at 500.

Thanks!

 

Stop throwing parts at it. That's unnecessary and gonna get expensive QUICK. Check your timing. Pull the top covers, line the marks up and see if anything is off. There are threads in here to show proper timing marks. On the 4.7l its NOT 0. It's a lil dowel/tit mark on the bottom cover and the letter T on the top for your cam's.

 

O2 sensor won't cause a misfire by the way.

 

Okay Thanks Ill do that. I has to drive my truck an hour to get to my shop where I can pull it apart and look at it. Do you think driving it that distance with it misfiring will cause any serious issues? Sorry if its a stupid question but I am new to this.

 

Idk if I'd risk driving it that far with a misfire.

 

Whoa horsey......yea stop throwing parts at it. Well now that you have all new spark plugs, correct? and what, 8 coils? If so, we know it's not that, and it usually never is that. So unless your timing belt jumped timing, which means , that's bad and should change that before you make things worse. Cam sensors could do this, but should throw a cam sensor code. Now there are these things called igniters located on the driver side by the firewall. I think there is 2, and each one will operated 4 cylinders. Now, I do have to confirm this and will get back to you. I know my 92 Lexus LS400 is just like that, and these are similar systems. I actually have spare igniters that I pulled from a Tundra in a junk yard and keep those with my spare coils in the back storage........and heed that warning.

 

Welcome

 

Well I think the problem is definitely timming. Here's some pics of what I got when I got down to the belt. Ordered a timing belt kit. Any tips? Thanks again

 

@mudsliger79 thanks for the help so the cam pullys should line up with the T not the red marks? And where should the crank be? I'm kinda confused by your line about the crank.

 

That little dowel to the right, on the bottom timing cover. Do not use 0 that's not the correct mark for a 4.7.

 

Yes, use the T. Not the red marks. Looks like someone was in there and just made their own mark's.

 

If you have any doubt as to were top dead center is (TDC) pull spark plug #1 and insert a long enough rod down inside and put a dial indicator on top of the rod and measure. You can almost get it perfect with the naked eye. Now looking at your belt, which is 100 times better than mine when I replaced my timing belt. So I doubt it jumped timing, but let us know for sure. I see these trucks have one igniter, so internally it could operate a set of 4 cylinders. I'm still looking into this, but I think igniter or cam sensor.

 

Every Video I have watched they used the 0 not the dowel. Whats the 0 for then?

 

Use the dowel. I speak from fucking the timing up on a Tundra at a young age and not listening to the master tech. Use the dowel and the T marks. I've seen techs do it. Just speaking from experience.

 

Dont know why that double posted the pic. Oh well.

 

The 0 is true TDC, the dowel is 15 degrees after TDC. By turning it 15 degrees ATDC tension is reduced on the vavle springs and you will less likely have the cam gear turn on you once the t-belt is off.
Using the 0 works, instead of matching to the T you would match to the I, but a cam gear might turn on you if you happen to bump the vehicle.
If you don't have a FSM (not sure if any of the tundra forums have one ) download the factory service manual for a 100 series Land Cruiser from ih8mud. The FSM specifically says to turn it 15* ATDC. Ih8mud also has detailed writeups with pictures of how to change the t-belt.

 

Like I said, if your not sure look at the piston. A piston at TDC is TDC no if's about it. I've done so many timing belts in my life I don't need a service manual. Use large paper clips to hold the belt on the cam so it doesn't turn. Put your own white marks on the pulleys.....and just put the belt on exactly as it came off. Spin the engine by hand a few times when done. The marks should all line up, if not, reset it. Make sure you have the right tension as well. That's the important part. You dont want it loose for sure, but not so tight you wipe out the water pump and possible bearings. BTW, I still to this day have not seen a vehicle were the timing belt has jumped. I've seen them loose to were it can affect timing some, but it's not going to be misfiring, just sluggish. I have fixed timing belt jobs were the previous person was one tooth off...........and most times I can fix that by just removing the top cover and some tricks up the sleeve. So TELL me this, HAVE you CONFIRMED you have voltage being delivered to all cylinders? YOU can put new coils in all you want, but if there is no voltage signal to the coil.............you have another issue.

 

When I had the same type of misfiring issues, it was due to shot spark plug coils. I replaced them all with aftermarket ones that have worked great for about 100k so far. And the whole price for the replacements was less than one coil from Toyota.

 

Do you have a pic of this ingniter or location I have the exact same problem as OP and changed timing belt all marks are dead on but now it will fire but not start I have fuel also so I'm lost for words

 

I had a plugged catylic converter cause the same issues. Check exhaust temps with a heat gun and compare before and after converter and both sides.

 

Gotta get it to run first but that was my next upgrade was to ditch the cats and run duel flowmasters

 

Was this issue resolved? What was the cause?

 

After a quick click on their username, I doubt they'll be answering any time soon.