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Camry Came Into Shop With CEL - Now Knocking!


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pooby92
User

Jul 11, 2020, 6:35 AM

Post #1 of 6 (207 views)
Camry Came Into Shop With CEL - Now Knocking! Sign In

Bear with me on the long post, any help here is GREATLY appreciated.

2002 Camry 3.0 came in with CEL
- This customer has no apparent running problems and just needs to pass the emissions test.
- I pull 3 codes – Knock sensor circuit bank 1, Lean bank 1, Lean bank 2.
- I clear the codes and drive the car to see if the codes will come back before I can set monitors, knock sensor comes back almost immediately
- I diagnose that code and it comes down to the piece of the KS harness that runs under the intake or the knock sensor itself. I give the customer the estimate for that job. I let them know that the engine is also running lean and I haven’t diagnosed that yet, but I will have the intake manifold all apart to fix that and there is a possibility of fixing a vacuum leak at the same time (if that is what is causing the lean condition)
- I replace both knock sensors and the harness. I drive the car again, no KS code this time but I can see on the scanner that fuel trim is very lean on both banks (about +15 at idle, but goes as high as +50 on acceleration). It gets leaner under a load/higher RPM, this leads me to believe it is caused by a lack of fuel and not a vacuum leak. MAF reading is normal too.
- I connect a fuel pressure gauge to the fuel line, it has 50 PSI – good.
- I run a can of injector flush through it. This is the strong stuff going through the fuel line using a pressurized can.
- I drive the car again – no change/still lean
- I go to work on a different job and let another mechanic look at it. He drives it with a scanner, looks for vacuum leaks, then goes to do some research online. He comes back to the car and starts it up and immediately it is making a god-awful banging. It sounds like a rod knock but lighter and seems to be coming from the top of the engine, not the block.
- My first thought is that some kind of debris got into the intake manifold while it was off and got sucked in. It’s the only thing that made sense to me, even though I’m super careful about not letting anything get in there. I figured either that, or the flush had loosened a chunk of carbon on the piston or intake valve. Or, possibly the timing belt hydraulic tensioner just completely failed and the noise is the tensioner pulley banging against the collapsed tensioner.
- I removed the timing belt cover, no issue with the tensioner. I drain the oil – no apparent metal in the oil or filter.
- I pulled the intake back off and looked at the intake valves on all cylinders. All valves looked fine, I didn’t see any dings or scratches to indicate a foreign object.
- I pull all 6 spark plugs. They are all normal except for cylinder one (passenger side, rear head). It is smashed flat like something hit it. I look more carefully at the intake valves and passage for that cylinder – nothing. I put a scope into the cylinder to look at the piston top. It has a layer of carbon on it and looks exactly like the other 5 pistons, no sign of impact or damage.
- I compression test cylinder 1 – 70 psi. I also put cyl. 1 on TDC and pressurized it with air through the compression test hose. I had an assistant holding a breaker bar on the crank bolt. He couldn’t keep it from turning, so apparently the cylinder is pretty sealed.
- I put it back together with a new spark plug in 1 and run it. The noise is still there and it is running rough. I pulled the new spark plug back out, it isn’t damaged.
- I pull off the exhaust manifold and look at the exhaust valves. They are a lot harder to see than the intake but I can’t see anything wrong.
- I pull off the valve cover and I see nothing wrong.

At this point all I can think of is to pull the head and see what I see. Anyone have an idea of what could have happened?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 11, 2020, 7:55 AM

Post #2 of 6 (204 views)
Re: Camry Came Into Shop With CEL - Now Knocking! Sign In

It sounds like you had the right instincts with the carbon or something dropped into the cylinder.

I'm somewhat still leaning toward the chunk of carbon theory.

Have you tried killing the ignition to each cylinder to see if the noise is effected? That 70 PSI compression is really too low so something is going on in that cylinder.

If something was in the cylinder it has probably done it's damage and blown out the exhaust now.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



pooby92
User

Jul 11, 2020, 10:12 AM

Post #3 of 6 (190 views)
Re: Camry Came Into Shop With CEL - Now Knocking! Sign In

There appears to be nothing in the cylinder now, and the new spark plug isn't being damaged BUT the noise is still there. I guess I'll pull the head off next and see if a valve seat broke loose and is banging against the valve. If it isn't that then perhaps a rod bearing spun when the piston impacted the plug? That sucks.....


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 11, 2020, 10:16 AM

Post #4 of 6 (188 views)
Re: Camry Came Into Shop With CEL - Now Knocking! Sign In

A rod knock should be pretty easy to identify. You should be able to tell if this is a top end or lower end noise.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



pooby92
User

Jul 12, 2020, 9:36 AM

Post #5 of 6 (169 views)
Re: Camry Came Into Shop With CEL - Now Knocking! Sign In

How? I haven't run it with the coil for cylinder one unplugged but that cylinder doesn't seem to be firing anyway and the noise is there.

At this point I have the intake, exhaust, and valve cover all removed. I think the next logical step is to remove the head and see what the valves look like and if I see nothing wrong assume I need to find an engine.

Is there something else you'd try before pulling the head?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 12, 2020, 10:01 AM

Post #6 of 6 (162 views)
Re: Camry Came Into Shop With CEL - Now Knocking! Sign In

I would have tried to pinpoint the noise location more before taking it apart.

Just because a cylinder is misfiring doesn't mean the ignition isn't still causing a piston impact and causing noise.

You may ultimately need to pull the head but I would have done more pinpointing of the noise first as it may be coming from the lower end.

These older Camrys were pretty well known for getting sludged up inside.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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