[Etnier]

For my part, I have a car at 94,000 mi. and should certainly change the O2 sensor. This isn't easy to search for here ("O2" probs): does anyone know of a writeup on the procdure to replace an O2 sensor?

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[flash]

2 types - a universal that requires clipping the wires and crimping new ones, and the oem - basically though, it's unscrew it and screw it in - you'll spend more time getting the car up on stands than actually doing the job



it's located down in the pipe by the cat - you had to unscrew it to install the header

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[Etnier]

Thanks, Flash.

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[Mark]

-Remove the oxygen sensor from the exhaust pipe. It is on top of the pipe just to the rear of the starter.

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[Tom in Austin]

Something that helped me ... take the O2 out while the exhaust pipes are still hot. They are much tighter when cold ...

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[Etnier]

An update: replacing the plugs with NGK Iridium's made the problem noticeably worse.



Thoughts?



FWIW: here's a picture of one of the old plugs, which had been in for at least 50K mi.

   

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[flash]

those plugs spark hotter and burn the fuel more completely - if the mixture is off it could change the symptom



still though, it sounds a lot like a disfunctional variocam or hall sensor - i'd disconnect the variocam and do another blink test to make sure it's picking up that circuit

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[Etnier]

Thanks, Flash. I'm sorry: I can't find anything on the Variocam in the service manual PDF I have on hand. Would I disconnect the solenoid? If so, I'm unclear as to how to: can I pull that wire bail to the right, away from the connector?



FWIW: If the car is idling in neutral and I floor it, there's a brief (1/2-sec) hollow 'pocketa' sound and then the engine speeds up.



[color="blue"]Sounds like this...[/color]



Again, thanks.

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[flash]

whoa! that is a real hole - almost like a huge vacuum leak, except for the abcense of the pop



i don't think the variocam would do that in nuetral



however, yes, just disconnect the solenoid at the valve cover to test - after reconnecting, you will need to disconnect the batery for a minute to reset the system

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[flash]

do you have a vacuum gauge? i'd be curious to see what readings you have

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[Etnier]

The blink test picked up the disconnected solenoid just fine. I don't have a vacuum gauge, but I'm going to get into my shop soon and have them look around. It's amazing how well this car is performing except for this problem: it is rarin' to go. The iridium plugs are now 'worn in' or something: the car is used to having them in place and the performance is much better than it was with the Bosch Platinum +4's that had been there for perhaps 50K miles.

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[ether_joe]

beyond my technical abilities at this point but looking forward to sounds of satisfaction when it's all taken care of <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[flash]

hmmm - well, that's good i guess



i'd check the vacuum lines next - maybe one popped off - like perhaps the fuel pressure regulator one when you were playing with the vanity cover?

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[Etnier]

Will do. I described this sound to Pete and he said it could well be the idle stabilizer valve functioning normally. That's where this sound comes from. I sent him the same sound clip that's posted here Friday afternoon: he hasn't gotten back to me yet.



I'll certainly poke around, and will being seeing 'the boys' soon.

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[flash]

hmmmm - i'm going to have to give mine a good listen when i fire it back up this week, but i sure don't remember any lag like that when you squish it - i know it lagged more than my last motor, but that thing was would up tighter than a 2 dollar watch, with a lot less mass in the engine to move



keep us informed

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[Etnier]

Yesterday I finally made it to a Run-Rite location which the RR people had located for me about an hour from here. $69.00, 1/2 hour, and it made a big difference. I'd unreservedly reccomend this for anyone with a car over, say, 80,000 miles. I'd been running Techron regularly since I bought the car, and had just completed a round of that and a can of Sea Foam in the gas tank, but the RunRite treatment has greatly reduced the throttle sag. I haven't had time to test things fully, but there's a major difference. Throtte response from idle seems substantially better, although that 'pocketa' remains-



[color="blue"]Before...[/color]

[color="blue"]...and after[/color]



I haven't heard back from Pete on this: I will be talking with him today. And more remains to be done: replacement plug wires are on backorder, and the car wil be checked at the shop next week.



But folks: if you have a higher-mileage car and don't feel like paying for a minor teardown, consider Run-Rite.

Pete at RS Barn recommends it, and now so do I. <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />

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[RS Barn]

John,

I've been itching to do a before and after leak-down test with the RunRite induction cleaning. It cleans deposits from the back of the intake valves that cause the valves not to seat. I know intake vaccum increases.

Also the injector cleaner used in that treatment is the best in the business. It doesn't have Alcohal that breaks down under engine temps and doesn't stay around long enough to really clean the injectors. I actually use their super duty injector cleaner (Sledgehammer). It even does a better job.

John I also bet you noticed a smoother -more steady idle.

I just did Anchormans car (other stuff too) and his ran noticeable better.

Pete

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[jaap]

Hi.



Just one question, looking at the old spark plug it seems the center electrode is almost gone? Is this just because it was in there for so long or is this indicating an engine running problem (too hot?).



Jaap

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[Etnier]

What make of plug are you referring to? Some of them (NGK Iridium comes to mind) have tiny electrodes in the first place.

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[jaap]

I just replaced mine with the standard bosch plug which has a much bigger center electrode not realizing the bosch platinum +4 would have such a tiny electrode when new. Sorry for the confusion



Jaap

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