Losing/misfiring cylinders

[buievonbozo]

I have posted this in other threads, including "problems and warranty issues" and in "classic", but I figured I would take the advice of someone and post here also. I am having major issues with the engine running very rough.
http://www.toyota-4runner.org/problems-warranty-issues/130764-losing-cylinders.html#post1259597
and
http://www.toyota-4runner.org/classic-t4rs/47849-engine-missing-not-all-cylinders-firing.html
ok... here is what I found, and it's kinda confusing.
Plugged in to handheld that my mechanic loaned me, codes came up as follows;
p0300- generic multiple cylinders misfire
P0301- cylinder 1 misfire
P0302- cylinder 2 misfire
So I figured since these two are connected by the coil pack waste spark system, the problem would be the coil pack. I changed it. The truck was still running rough. So I plugged it back in to the hand held. Now the codes came up;
P0305- cylinder 5 misfire
So i pulled that pack off and swapped it with #3 cylinder and checked the plug which seemed fine. Put everything back together and started it up. Still rough. Plugged it back in and this came up;
P0300- generic, misfire on multiple cylinders
P0301- cylinder 1 misfire
P0305- cylinder 5 misfire
P0306- cylinder 6 misfire
Now, I checked these codes against a software program at my mechanics garage and it gave me a list of possibilities.
Cam shaft timing
fuel pressure
fuel injectors
multiple ignition issues (plugs, wires, coil)
So, I took a can of starting fluid and sprayed it everywhere to see if it changed anything, just incase, before i took everything apart again and nothing changed. Got everything off down to the injectors and fuel rails. Noticed that 3 plugs were a 1/2 turn loose. All plugs seemed equal in burn color. Boots all snapped on nicely with good connectivity. Checked the seating of the injector seals, seamed good and tight. Checked for breaks or wire disconnects on injector electronics, seemed good. Put everything back together, completely stumped. Started it back up and of course, still running rough. Plugged it back in and #1 and #5 came up again as well as another code (forgot it) for system coolant level being insufficient. I checked that and the level is fine. WTF!!?
Now 2 months ago, give or take, I changed the plugs, wires, packs and injectors and it ran fine, as stated before. Then everything went to hell. I don't think the timing would be off cause, though I changed all that stuff, it would not have made a difference. I have yet to check the fuel pressure. Can someone give me an idea on how to do this?
I got this truck for free, being that it did not run before, and I replaced everything and a few thousand dollars later is was fine for a couple years. Now this. I am ready to throw in the towel.

 

[djtc]

I have a very similar problem .Is yours running rough at idle only or throughout the whole rpm range?

 

[buievonbozo]

throughout. I can't figure it out. I think the next thing is to do a fuel pressure test. Maybe the regulator is clogged from the ethanol. I changed the fuel filter as well and blew the system out from the fuel rail to the filter connector. Its gotta be something electrical or to do with timing. I have no idea quite honestly. Just grasping at straws here.
It's funny how so many posts and threads are related to this issue but no one has a sure fire solution.
This really sucks!

 

[fourwd1]

OK, are you getting a good solid 13.8V or more to the coil?
If the input voltage to the coil is low, the high voltage output will be low, and if it's too low your going to get poor ignition.

 

[buievonbozo]

I will check that. Thank you! That is the proper voltage for the 97 V6? If this is the case, what would be the next step? And would this issue cause different cylinders to misfire sporadically like the issue that I am having?

 

[buievonbozo]

Ok guys. Did the work this weekend. I ordered new injectors and a pick up screen.
Dropped the tank and cleaned that baby out. Amazing how much crud builds up in there. Disconnected the fuel filter and blew out all of the lines, starting with plugging random ports in the fuel rail, spraying it with cleaner and blowing them out. Got good results. Then I sprayed and blew out the fuel line from the rail to the filter, then from the tank to the filter. Put everything back together and presto! Truck runs great again. But we will see. last time, it took a little while for it to start fouling up again. I think that was just because I was a MORON and didn't think to change the fuel filter.
Fingers Crossed!
Thanks again for everyones input.