^^ The tapping sound is the giveaway. Pop the hood and scope the motor. Broom sticks, metal rods, etc.. make good scopes.
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If you're not familar with the scope-

"if you have a broom handle that you can use that is sawn off flat on one end. You can place it against the block in several areas and put your ear to it and hear the local noise of the engine more distinctly, especially knocks etc."

This will put you closer to knowing where the noise is coming from.
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Man, I wish this was an easy fix. I know it's not gonna be.
Wouldn't surprise me if that's what's going on Halbert.
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Either way, good luck brother. Please report back when you do find out.

When I owned a 300z, I really wanted a supra. :-)
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Any updates on the yota?
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Haven't had too much time to get under the hood unfortunately. I've been driving a lender for now. Tomorrow I'm off work and I think my dad and I are gonna fart some more with it then.
I'll let ya'll know...
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Ok, very odd thing happened.
Let the car sit for a while because we didn't have time to get to it.
After about a week of doing nothing it all, it ran like it normally does (with the exception of the gasoline still smelling a bit rich.)
no black smoke. no power loss. Just a low idle.

Reset the ecu and we replaced the fuel filter. The filter we replaced was completely full of junk (Again).
Apparently my gas tank is full of crap.

The ticking noise is gone.
I'm gonna keep driving it around to see if it happens again...
I'll keep you all posted.
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Question: Do you remember the weather when it started acting up? reason I ask, I've just decided the mis-fire I'm getting periodically in my truck is rain related. I'm thinking I have a stopped-up drain below my windshield that is allowing rain water to overflow, filling the spark-plug well with water, and drowning out that plug wire. That misfire results in heavy gas smell in the exhaust, bad gas mileage, rough running. But several days later, with dry weather, it straightens up completely.

Possible you are having something similar??
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It was dry outside I believe.
Also dry outside today when I went driving.

No black smoke. No power loss.
However, the idle is severely low when at a stand still and the car will die. Even when I'm braking, the car will die if I don't keep my foot on the accelerator. This of course is a problem, as the transmission slips through the down shifts when I do this (it's an automatic). And of course, it's really annoying. We're going to play with the idle tomorrow after I print off some diagrams.

Still not sure what's going on here, but I'm under the impression it's computer related.
I'll keep you all posted.
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Fuel injected? with computer (probably)? May not be able to adjust the idle. Maybe can. I've had them where the computer would override the small amount of adjustments many systems allow!

Have you checked the throttle flap inside the tube at the intake? My pathfinder has a periodic need to have that area cleaned. It gets gummy, and there are a couple of small holes in that area (on the pathfinder) that get the "gummy" film covering them, and that really screws with the idle rpm and the low rpm power. I end up cleaning this area about every two years (when it was a daily driver). Be warned, though, some manufactures (Ford is one) warn about cleaning these areas, stating that there is special coatings for these surfaces. My 1997 ford warned of this. Cleaned it any way, and haven't had any problems from it. in the event you clean it, gasoline works about as well as anything, and since gasoline is what the basic gumming is caused from, gasoline has less chance of causing damage (though, obviously, using gasoline as a cleaner has heavy risks involved!). Personally, I've always used carburetor cleaner without issue.

Might be worth a try. Just take care NOT to touch or damage the mass-air sensor that is located inside the ductwork! very expensive to repair. Good luck!
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My Bonneville would have a slight rough and slow idle, plus the SES light.
The SES code showed Mass Air flow sensor problem. Before spending $130.00 for a new one I bought some Mass AIr flow sensor cleaner($7.00) and used it. So far so good, no more idle problems or SES light, all gummy gunk removed.
This Cleaner is suppose to be safe for fragile electronics in that area.
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We've talked about the mass airflow sensor.
Perhaps I'll look into cleaning that area. Can't hurt at this point.
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This is what I used.
http://shop.advanceautoparts.com/web...23-132410707-2
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Yep! many problems can be traced there. My son. in his 2005 F150 developed an acceleration drop-out a day or so after he cleaned and recharged the air filter. Major power drop-out like the fuel pump was shutting off. A cleaning of the MAS corrected it. Just make sure, if you are working with it, that you use a specific cleaner meant for it! Cost of MASs can run in the $500+ range for some models!!
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We removed the O2 sensor near the exhaust and that seems to have fixed it for now.
Gonna do some more driving, but apparently this was the main problem...
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What was causing the tapping? :-)
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Not sure. The tapping has since disappeared.
The whole thing is still a little fishy so I'm going to be keeping a close eye on things.

Running well enough though. Floored it this morning through traffic and the car got up and went.
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If it was running rich because of the O2 sensor, it could conceivably make the valves tap, right? (Because there would be too much fuel mixture behind them for them to close.)
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I reckon so. Still seems odd.
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You don't have to tell me how odd it was. Never encountered a problem quite like it.
I reckon the car could use a good old fashioned tune up
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