Distributor shaft turns so that the rotor is misaligned

toyota
pickup

#1

While my engine is running my rotor suddenly turned to no longer be at the #1 sparkplug wire when #1 piston is tdc. It is 180 degress off. This causes a backfire and stalls.


#2

Did you, or anyone else have the distributor out?


#3

If you had somehow spun your distributor rotor 180 degrees out, the engine wouldn’t run at all. It’d be firing on the #3 cylinder when the #1 cylinder was at the top of its power stroke (assuming a 4-cylinder) or the #4 cylinder when the #1 cylinder was at the top (six cylinder).

What led you to believe it’s 180 degrees out?
What are your actual symptoms?

And, of course, what are the year and engine of your Toyota. And the truck’s mileage.

You do realize I hope that the sparkplug fires every other time the piston comes top-dead-center rather than every time? And that the camshaft operates at half the revolutions of the crankshaft?


#4

[quote=“the_same_mountainbik, post:3, topic:106124”] … You do realize I hope that the sparkplug fires every other time the piston comes top-dead-center rather than every time? And that the camshaft operates at half the revolutions of the crankshaft?
[/quote]

I hope you realize that SOME engines fire every revolution - one of which is on the exhaust stroke. I don’t know enough about the particular vehicle in question to say this is the case, but I wanted to point that out to any readers who are unfamiliar with that sort of set up that it does exist.


#5

IF it has a distributor, it is not one of those engines.


#6

You’re right. There are some engines out there that fire two plugs at a time with one shot from the coil called “wasted spark” engines. These suck, but there are some out there. I don’t know what the timings of the “wasted sparks” are, whether they’re 180 degrees out (on the exhaust stroke of the other cylinder) or not.

However, to the best of my knowledge, Toyota has never used them.


#7

The distributor turns at half the speed of the crankshaft therefore the rotor is near #1 at TDC on one stroke and at #4 on the next stroke at TDC. Number 4 is 180* from #1.


#8

Look closely…2001 Toyota:

Notice plug wires going to the left and around to the back bank.


#9

The distributor will appear to be 180 degrees out at tdc as often as it is spot on. It alternates, that’s normal. That’s b/c in a 4 cycle engine the crankshaft turns a complete circle twice for every time the distributor turns a complete circle once.

This isn’t to say the distributor isn’t 180 degree out, that could happen I suppose, but OP should make sure they aren’t mis-interpreting what they are seeing. At top dead center every other crank rotation the distributor is 180 degrees out, that’s just the way the engine’s ignition system works. My guess is that the backfires and stalling are caused by something else. What does your timing light say is happening?