4AFC firing wrong

[Pimpin_1JZ]

Hi,

I have an AE92 4AFC Corolla, and it seems to be running on a bit when I go to turn it off and has pretty crappy economy. So I've gone to check the timing, but it is actually firing wrong. When I have the timing light attached to the number 1 cylinder, it seems to be firing 180 degrees from top dead centre (the underside of the car). I have checked that everything lines up for TDC and everything does (the hole on the camshaft pulley lines up with the inlet camshaft bearing cap, the two indents on the cam gears line up at the top, the rotor button in the distributor lines up at the number 1 cylinder and the crank pulley lines up at the 0 degrees mark). I am stumped, I want to time my car but can't because I can't see mark with the timing light. It is firing before it is supposed to. All of the leads are right going by firing order 1342 which I'm pretty sure it is.

Any ideas?

[VasH]

when you say running on abit you mean like pre-ignition? sort of stutters and splutters after you turn off? Stuffed spark plugs can be the cause of this

I found at first mine was pretty hard to see the mark on the balancer aswell, try cleaning up the balancer with a wire brush, you have to look in from an angle from the front of the car to see it clearly

the car is driveable yea?

[Pimpin_1JZ]

The car is driveable and the plugs have been changed. I can see the mark on harmaonic balancer easy enough, I have marked it with some white marker pen. The problem I'm having is that it is firing 180 degrees on the harmonic balancer before it should be, ie; it is no where near the mark where it should be. The distibutor isn't in 180 degrees either as it can only go in one way.

[VasH]

how close can you get it to the mark by adjusting the dizzy position while its running?

i know you have said the plugs are ok but you have earthed them out and actually checked for spark? (just making sure )

pretty sure it wouldnt run and you would get it back firing out the carby if it was that far out.

[Pimpin_1JZ]

Haha yeah checked spark on all, and it seriously is that far out, it is doing my head in. I advance the distributor as far as it can go and I still can't even see the mark with the timing light from the top.

[VasH]

im guessing this happened after it ended up in the dam lol?

[Pimpin_1JZ]

Hahaha nah, I have been meaning to do the timing from the start but never did. It says under the bonnet to remove all hoses from the distributor and block them to do the timing. But can't see the mark with the light, but with it all connected you can see the light :S.

Oh well I just timed it off that and left it at that.

[oldcorollas]

you either have the timing light on the wrong lead...
or you have marked the "other" timing mark on the pulley.

check there is no mark 180deg from the mark you made. sometimes there is 2.

there is NO WAY that the engine will run, if EVERY cylinder is firing at BDC....

running on is due to hotspots or carbon in the combustion chamber, allowing fuel to ignite after you turn off key (which removes spark power).
it also means that the solenoid in your carby which is supposed to cyut fuel to the idle circuit when key is turned off, may be stuck open.

[oldcorollas]

you remove the hoses from the dizzy, so that there is no vacuum advance when you set timing.

if you time with the hoses connected, then you might be setting the timing 10 or 20 deg too retarded.. which might explain your shitty economy

[Pimpin_1JZ]

That's the thing it is definately on the number 1 cylinder. I did try it on the second cylinder and you could see the mark with it attached then, but not when it is on number 1? From what I can tell it is firing pretty much what you say so I'm kind of stuck. There is only the one mark on the harmonic balancer and I have checked and double checked everything else.

[2jzhilux]

Could the timing belt be out a tooth or 2?
Have also seen when the keyway is flogged out on the crank you can get the keyway dug out in the other side of the crank maybe this has been done before?

[oldcorollas]

ahh, keyway could be dead, but 180deg?

if you turn engine, so that no1 piston is TDC, and the dizzy rotor is pointing to no1 lead...
where is the mark? on top or underneath?

(is the timing mark on the case under? or on top?)

basically, there is a mechanical relationship between the piston and the mark. if the timing mark doesn7t line up with the piston, then the mark is wrong. check that first

IF it is wrong, check crank pulley bolt tightness... if tight, maybe make a new mark, for when piston is TDC...

[Pimpin_1JZ]

if you turn engine, so that no1 piston is TDC, and the dizzy rotor is pointing to no1 lead...
where is the mark? on top or underneath?

When this is done, everything lines up as stated in the first post, The mark on the harmonic balancer is at the top right at 0 degrees. It is just firing too early. which is either a 1/4 of a turn before on the dizzy or 1/2 a turn before on the crank. But then you bring it back to TDC and everything lines up again?

[allencr]

I did try it on the second cylinder and you could see the mark with it attached then, but not when it is on number 1?

2 or 3 are exactly 180 from #1 and #4 is exactly the same as #1, give or take a degree or 2 for manufacturing tolerances.
Either way, the only thing I think a timing light is good for, is checking that the mechancial, vacuum or electronic advance actually operates, so I'd ignore its use for anything else.

Just set it so that it runs well, idles fast & smooth and only pings/pinks/spark knocks/detonates when abused, when using the octane of your choice.

[godlovesugly]

my 3tc has the exact same problem so i am subscibing.