83

This is my first time working on a 5vze. I'm starting the valve cover gasket job.

Before I start pulling spark plugs and coils, I want to understand the wire routing. I'm used to one wire for each cylinder. Four for a four cylinder. This truck has 3 for a 6 cylinder, and they are numbered 1, 3 and 5.

So I'm assuming there's one coil for two plugs. The coil sits on top of one plug, then the wire for the plug on the other head runs out from there. So ok, then 3 wires makes sense. But the order is strange to me. Rather than #1 being in the front, they seem all over the place. The wire that says 1 goes from the first cylinder on the passenger side, to the middle cylinder on the drivers side. Wire 5 goes from the 3rd cylinder on the passenger side to the 1st cylinder on drivers side.

So other than just drawing myself a map, where is the reasoning I can use to make sense of how these run, and why the wires are labeled the way they are? It would help if I actually understood it, instead of just drawing a map...

Or should I even be paying any attention to the numbers on the wires? Not sure if they're OEM.

rworegon

http://www.toyota-4runner.org/attach...s-zcruiser.jpg

The link above may help you out.

wyoming9

iTrader: (1)

Don`t go by any numbers on the wires .

Just replace them like you take them off

83

Hey now I don't have to draw my own map. Thanks.

83

Ok, thanks.

I'm just so used to a much more simple, obvious layout. 4 cylinders. Number one is the front one and they go back from there. 4 spark plug wires. Nice and easy. But that's ok. I don't see being back in here for a long time. I'll have to ask my friend when the last time was that they were replaced, but I think it's been quite a while, and the old plugs looked like they were totally fine.

I'm almost ready to put the valve cover back on the passenger side. Just need to replace the cam seals then I'm done. Then on to the drivers side. So far no unwanted surprises...

vital22re

iTrader: (2)

if you buy sumitomo brand from the dealer, it comes with all the clips and is preassembled so it just plugs in. They are also stamped with the year they were made so if a 5vz still has the oem plug wires you'll know the last time they were replaced.

83

Ok, thanks. Wires may have been original, but plugs were not. They were 4-prong. I kept all the original clips. Though if I had to do it again I'd get it all from the dealership. The wires and boots were the only thing I didn't get from Toyota, but I did get NGK. Don't remember now why I got those from Rock Auto and everything else from Toyota.

TheDurk

The map is great, but the quick and easy way is to remember the difference is always three.

1-4
2-5
3-6.

It's that way so the two cylinders at TDC, one on each bank, fire at the same time--but only one is full of fuel. The other is the "waste spark" and occurs between exhaust and intake.

The two cranks are set up so the compression firings occur in a balanced manner, so there is logic in the wiring map, that may not be immediately apparent. Believe it or not, that order is 1-2-3-4-5-6. Now, if you go back and look at the wire connections I posted, you see the ECM fires the cylinder pairs in sequence from top to bottom and then repeats. So the front pair of cylinders fire first, then the middle, and finally the rear. Rinse and repeat.

The NGK wires are fine. I have 80k on mine. Lots of us use them. For years, the dealers only sold Densos, and the OEM Sumitomos were just not available anywhere in North America.

83

Huh. So it starts on #1, and at the same time fires a spark in #4(which has no fuel going to it at this time? Or just no compression?) which is "wasted". Up through #2(5) and #3(6), then does the same thing, but on the other head? So it's firing #4 and #1 is the wasted spark?

Yeah I think I was reading that either NGK or Denso would be considered OEM replacements, more or less. The spark plugs I got from Toyota were Denso. I guess had I known that before, I would have gone with Denso wires, but I'm sure that's just completely unnecessary.

TheDurk

Well, you had it right until you wrote "other head." The firing cylinders are on left 1, right 2, left 3, and so on (looking from front). The waste cylinder has neither fuel nor compression when it gets the spark. Exhaust valves just closed, intake valves are opening, cyl is at TDC more or less (5-12°BTDC). Physically it moves in tandem with its twin, but the valves make it 180° out of phase in terms of the 4-stroke cycle: intake, compression, power, exhaust.

83

Hmm...well I'll have to think on that for a bit Partly, though I understand a lot more than I used to, I guess in a sense I still don't understand enough about how the engine really works for these things to really be clear to me.

But thanks for the explanation!

Malcolm99

Did TheDurk say " The two Cranks are set up so the compression occurs in a balanced manner" I think he means that the Crank journals are set up so the compression strokes occur in a balanced manner or perhaps he meant to say the 4 Cams, never seen a 5vz-Fe with 2 crankshafts

TheDurk

Sorry, of course, two heads, but one crank. Fingers were working without brain fully engaged.