timing belt- will car run if 2nd cyl is tdc

skep

Forum Member
Joined
Jan 16, 2015
Messages
59
Location
Mornington Peninsular,Victoria, Australia
Car Year
2003
Car Model
Forester xs
Transmission
Manual
edit..ej20t struggles to idle then dies

Hey fellers! just did the timing belt on the 4 cam wrx engine (replacment and never saw running) and has intake popping and then dies within 5 sec. with the intercooler off its sounds good and revs up high then dies after a few sec. there is a huge delay when i touch the peddle and the revs surge but it will stay running, so just wondering (hoping) i didnt rotate the crank pulley once and brought u 2nd cyl at tdc as I was unaware that it takes 2 turns and thats why it sounds like its missing badly and dying. is that possible or would it be that far out that it wouldnt fire at all? turns over nicley but when it starts it is very rough. BTW all cams and teeth line up, plugs arn't that old and leads should still be good, cheers boys.
 
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it won't run properly with the IC off.

The MAF (intake airflow sensor) will be sensing no airflow and it'll be putting in a matching amount of fuel and running super lean.

Pull the timing cover and check the cam/crank marks are ok - safer than mucking about and trying to guess whats up.

I don't understand what you mean by 'rotate the crank pulley once'.. - sure, the cams rotate at 1/2 the rate of the crank, but it doesn't matter where you started, as long as the marks are correct.

Pic doesn't show it, but there's a mark on top of the crank sprocket which lines up with a belt mark, too.

timing.jpg
 
it actually works and sounds better with the ic off but dies of course, compared with all of the intake fitted, almost like its choking.....as for the crank i read that it takes 2 full spins to bring 1st cyl back up to tdc and thats why I am wondering if i rotated it with the belt off a full turn for some reason as i was spinning everything :lildevil: but thinking last night that the engine would be all at 180' off with the 2nd piston up so it couldnt possibly start. ill runs some foam through the lot as i had my manifold off for a couple of weeks and see if that can clean injectors etc, cheers!
 
skep -- there's no two rotations malarky.

One crank rev will bring #1 to the 'top'. Whether that's TDC or 360deg out depends on where the CAMS are.

With the timing belt removed, there is no sense of TDC or 360deg away from TDC.

There's a crank angle sensor - which only tells the ECU where in 360deg of crank rotation the engine is, and a CAM angle sensor, which (because it rotates at 1/2 of crank speed), tells the ECU where in 720deg of crank rotation the cams are.

It takes two spins to bring the engine to TDC if the timing belt is on.

one saving grace is if it turns ok, chances are you didn't bash the valves into the pistons, or each other -- though bad running could be caused by a bent valve.
 
ALL GOOD!!! it was the wire harness under the intake manifold proping it up and manifold not sealing properly....... blew some smoke for 5min on startup but runs all good now......
 
glad its sorted - always the simple stuff.

When idle is all over the shop and uncontrolled -- always suspect a manifold leak!
 
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