AOS - Question

[Smallblock454]

Hello Muskoka Minute,

so the car did run well for a short time (3 miles) and than these noises and the engine light came up. That noise doesn't sound good.

That noise is not a DMF. You will hear a bad DMF only if you engage the clutch at the point between slip and engagement - mostly in first or reverse gear at lower revs.

What to do:

1. step)

• If you have a Durametric or any other diagnostic tool note all error codes and check their meaning.
• Unconnect the starter battery.
• Pull all spark plugs and clean them. There might me oil and crust on them. Check the electrode distance.
• Turn over the engine while the sparks are out. Aprox. 2 times for 5 seconds. Check if oil is coming out of the spark plug hole and how much.
• Put in all sparks.
• Remove the MAF and clean it.
• Remove as much of the air intake system after AOS and MAF and clean it. There will be lots of oil in it.
• Put everything together, connect the starter battery.
• If you have a Durametric or any other diagnostic tool reset all errors.
• Start the engine.
• If it runs without unususal noises or anything else – OK.
• Do a test drive.
• If you have a Durametric or any other diagnostic tool check error codes.
• If you don't have codes or anything else – repair done.

If you have the same noise and the engine is not running well like in the video, we have a bigger problem. In that case do not drive the car or start the engine.

2. step)

• Do a pressure test for each cylinder.
• If all cylinders are in the same compression range, use an endoscope to take a look at all cylinder walls.
• Drain the engine oil. Check what you find in the oil filter.
• Unmount the engine oil pan. Check what you find in the oil pan.

If can't find something unusual, start the engine and check if you can identify where that hard knocking noise is coming from / if you can locate it.

Hint: Don't do a compression test without engine oil in the engine.

Hope you don't need to do the 2. step.

Regards, Markus

[911monty]

Thanks Markus I was trying to be optimistic that's why I said hopefully! I think there needs to be a sticky somewhere on the steps to take after an AOS failure, I modified your steps as a first attempt. Hope you don't mind


What to do: Do Not attempt to start the engine until all steps below have been completed as serious damage to the engine can result!

1. steps to take after AOS failure.

• If you have a Durametric or any other diagnostic tool note all error codes and check their meaning.
• Pull all spark plugs and clean them. There might me oil and crust on them. Check the electrode distance.
• Remove Fuel pump relay.
• Turn over the engine while the spark plugs are out. Aprox. 2 times for 5 seconds. Check if oil is coming out of the spark plug hole and how much.
• Put in all sparks plugs.
• Remove the MAF and clean it.
• Remove as much of the air intake system after AOS and MAF and clean it. There will be lots of oil in it.
• Install fuel pump relay. Start the engine.
• If it runs without unususal noises or anything else – OK.
• Do a test drive.
• If you have a Durametric or any other diagnostic tool check error codes.
• If you don't have codes or anything else – repair done.

[SeanBuller]

Hi Guys,

We are currently trying out the procedure listed above. We swapped the upstream O2 sensors between bank 1 and bank 2 (bank 1 is misfiring). We cleared the codes for the vehicle and started it up. Still idling poorly and making the noise in the video above.

The CEL did not come on, but we are getting code P0012 which says "intake camshaft position timing -- over-retarded (bank 1)". Along with P0300, P0301, P0302, P0303. All relating to misfires of cylider 1-3 (Bank 1).

We have cleaned the MAF and now replacing all 6 spark plugs.

Is anyone familiar with these symptoms? Especially P0012.

Thanks!

[911monty]

Hey Sean; Before you reinstall those spark plugs, I'd recommend doing a compression test. If you do not have one there are loaners available from AutoZone, O'reilly's etc. Unfortunately it may be time to implement Markus' phase 2 plan. Hoping for the best!