spark plug wires swapped

[jkamaraj]

Hello all,

i'm a new member to this forum. I recently bought a 2000 Toyota camry for my wife. after a year she started to have cold start issues. so first i checked the coolant temp sensor and it turned out ok. then i thought it already has 140,000 miles so why not replace the spark plugs. when i went to remove the spark plugs i found that the connection is as follow from the ignition coil to the spark plugs

spark plugs ignition coil
1 1
2 3
3 2
4 4

i thought that it was wrong. but it was running like this for the last one year without any problem. so i went ahead and swapped the wire. and i'm going to test it for a couple of days before i replace the spark plugs.

am i right or wrong

please help me
jc

[toyomoho]

How many coils does the ign system have, 4? Or 2 coils grouped together. Each coil has 2 wires coming out of it.

Suggest you leave the wires where they were.

[jkamaraj]

i think it has two coils. two sets of coils one coil reads 1 4 and the other reads 2 3
yes each coil has two wires coming out of it
if the wires are marked wrong won't it affect the firing order?

thanks
jc

[new echo owner]

No, both plugs fire at the same time, as long as they are on the right coil, you are fine. Waste spark ignition system; one fire from positive to negative, one fire negative to positive.

N.E.O.

[toyomoho]

On these 2 coil setups, each coil fires 2 spark plugs at the SAME time.

When 1 plug is firing on a cylinder at TDC on compression (the right time) the other is firing on another cylinder at TDC assuming the exhaust stroke (the wrong time). This exhaust stroke plug firing is not required and is wasted.

Why did Toyota go this system, perhaps to improve ign performance and still save cost. Or they would be using one coil for each plug.

Thus when one coil is firing the No 1 spark plug at TDC compression stroke you want the other plug wiring firing a cylinder that is not going to ignite.

The engine firing order is 1-3-4-2.

The outer cylinders (1 and 4) move up and down in sync with each other. The two inner cylinders also move in sync with each other (2 and 3).

No 1 cylinder is closest to the passengers fender.

On the old setup what cylinders was each coil connected. Example: coil 1 want to cylinder a and b, coil 2 to c and d.

[jkamaraj]

that's amazing. it is good information. i would have never guessed that the design wants two spark plugs firing at the same time. may be it made sense to toyota(save money on two ignition coils).
i went ahead and swapped the spark plug wire. i will go back and restore the original setup(as it doesn't make any difference).
thanks all. i'm an engineer working for CAT developing diesel engines. compared to our diesel engines these engines look pretty complicated
jc

[toyomoho]

This ign system may have worked OK with either wiring setup but why take a chance until you have determined it is OK.

If your just swapping wires from the same coil between the same 2 cylinders it fires it should not make a difference.

CAT yes, used to repair and drive their products back on the farm, D6 and D8. Great products!