'98 Camry Engine knocking/EGR questions, please tell me what you think

[Soilent Green]

I got a '98 Camry 4 Cyl Auto (267 000km, about 166 000miles)

The engine is knocking/pinging pretty badly when I start her up in the morning, then after few minutes it goes away and doesn't come back for the day, either when accelerating harder or going uphill, even if the car waits outside from 8:30AM to 5:30-6:00PM. There's a puff of blue smoke as well on the first start of the day. It was also knocking this winter on freezing mornings, even after a good warmup (needle on the middle mark). I don't remember about last summer when I got the car though.

I'm guessing it's probably the piston rings, but a bad EGR valve could also cause knocking, so I wanted to change it. I've been wanting to change it for a while now actually because of idle issues, but regular cleanings of the throttle body helped so I got break jobs and suspension jobs instead. But now I realize the car still knocks in the morning even when it's hot outside and it bothers me, so I want to go with the EGR replacement ASAP. The thing that bothers me even more is that I don't want to throw money on an EGR valve if that's not gonna help the knocking problem to this point. I'd rather have a car that doesn't knock in the morning than a car that idles perfectly, but both problems could be linked to the EGR valve so I was wondering and took a close look at the components under the hood, and now I don't really know what to think. Could somebody clue me in on this?

The EGR valve is pretty rusted. I've been getting crappy idle for a while, and more recently I noticed funny machine-gun speed "tss-tss-tss-tss" vacuum noises near the VSV for evap next to the air filter box. I couldn't find any vacuum leaks around the VSV ports no matter how hard I tried and the hoses look fine. When I put my fingers around the EVAP hose (the one that goes from the right port of the VSV to the top of the Throttle body) I can feel the pulsations on time with the vacuum noise. If I squeeze the hose the noise stops and the engines slows down even more, wich is probably normal. If I disconnect that hose the engine goes up to 1000rpm, and there's a pretty sharp vacuum going through that hose to the TB when I put my finger on it. The air flow is not pulsating so it's not clogged up to the Throttle Body. When I reconnect it, the engine drops back down to it's usual idle speed and starts wich the shaking again. It almost dies when the hose first touches the VSV port, then stabilizes when the hose is secured tightly. I guess the VSV could be malfunctionning, or maybe an EVAP canister component further down the road? But then none of these are directly connected to the EGR valve so could the EGR valve be so screwed it breaks normal vacuum flow through the entire system? And what about that knocking?


CEL is also on code P0446, no other codes apparently. After a lot of searching on a couple forums, P0446 should be linked to a faulty VSV on the canister so I whip out the Haynes and spot it, then I see a third VSV in the manual, located to the front of the engine wich is called VSV for EGR. All I see in there is the oil pressure switch and the connector for oxygen sensor but no vsv. Is that one an internal component?

I really want to get rid of that pinging in the morning but this kind of leaks into an EVAP issue....I don't undertand how a bad EGR could make an engine knock, but since I've been suspecting mine for bad idle and read about it causing knock I decided to investigate and all kinds of things seem to be clashing together now. I'm swinging between piston rings and EGR system or maybe even ignition components like coils or plug wires, but I'm very confused.

Knocking is my first priority but I'm not even sure it's the EGR valve after checking the entire thing, should I change it anyway or get someone to check the piston rings? Two different problems? One ignition coil failed last summer, could the other one be going out as well? The car seems sluggish when taking from a stop...spark plugs wires? that related to pinging?

So many questions...

[popeye08]

Just some clues for you:

1. Make sure it is from the engine not others. My 96 Camry LE 4 cylinde got extrodanary noise in the morning for a while after I checked it seems come from some bearing in the chain of drive belt. Only once in one day too.

2. Did you locate the VSV correctly? In my car, it is on the back of engine and can only be reached from right bottom. Just folllow the rubber pipe of the EGR. The VSV near the air filter is for the fuel not for the EGR.

3. You can check the EGR by this: take off the pipe of the EGR on the top and connect one similar pipe on it and use your mouth to suck it. When the engine is running, you can feel the difference, it will almost die when you suck and open the valve. If it is the same, your EGR valve must have some problems.