Even though it is about five feet back from the turbo, when I set the valves, twice, and torqued the head bolts between sessions, it idled for a long time, and got very, very hot. It indicated very rich ratios after that, which I do not believe. It ran too well for the ratios I was seeing. I think I need to move this sensor further back. Next time I will remove the sensor for extended idling, tuning, etc.

I will let you know if it is better in the morning, after it has cooled down.

Sam

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I would think the sensor would be designed to handle prolonged idle sessions. What you did would be no different then idling thru rush hour traffic for a few hours, a common occurrence in some parts of the country.

Becareful moving a sensor, especially when hot. I recall reading they are prone to shock damage. Also do not run the engine with the sensor unplugged - if the heater in the sensor isn't active carbon in the exhaust damages the sensor when it normally would be melted away.

Assuming the sensor isn't too close I agree with kesteb, length of time idling shouldn't matter. If the sensor is too close, this would explain your Innovate troubles too.... Do you have an IR thermometer? I believe the Innovate manual included a sensor base temperature spec.

I wonder where the sensor is located in a stock VW application.

Drove the car to work today and displayed AF ratios are back to normal. I think I will look into finding an extension for the signal cable and move it back.

Sam

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Maybe the culprit is condensation. On the way back home yesterday it misbehaved just the same way the Inovate one used to. It worked fine for about 10 minutes and then, instead of an error code, which the Inovate would report, it just gave bad info.

As it turns out, I was driving back from a shop where the guy builds street rods. I was there asking about exhaust work. So I asked him about the O2 sensor and the possibility or moving it further back, and he said "NO, that is where they are supposed to be" I told him how it was misbehaving and he said, (and this is the big one), "That is how the act when they get wet".

So I am wondering if it is too far back. Is the exhaust expanding and cooling too much, and moisture condensing out of the mix? Does anybody know if the moisture puddles at the bottom of the pipe or is still a vapor or mist at this point in its expansion process. I know it is liquid, and puddling by the time it gets to the outlet. Any scientists out there familiar with this phenomenon?

If this is the culprit there are two possible fixes:

1. Move it closer to the turbo outlet. It is 5 feet back along the flow.
2.Move it further back and place it on top of the pipe, facing down.

I could face it down more where it is now. It is at the lowest point in the pipe.
But if I am going to move it at all, I might as well move it to a more ideal spot.


At least up until now, I have not been losing coolant. So if it is moisture, it would most likely be pure condensation. It has been very, very humid here. It was 90% yesterday, and has been for weeks, and weeks.

This problem always seems to crop up when the sensor is about 6 weeks old or so. It is as if they become more sensitive to something, (heat? moisture) with a little time.

The narrow band sensor was placed immediately after the turbo outlet. It seemed good always., Lou has his wide band one there, and has reported good results so far. I am wondering if I should stick it up there and see how it does.There is a plug in the bung now.

Does anybody know where VW places their wide band sensor? What other OEM applications use one?

Thoughts?

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Sam, moisture in the pipe is real bad for the sensor. If I read your post correctly, your sensor is in the bottom of the pipe? Or is it just where the pipe is lowest?

The sensor should exit the top section of the pipe, so that any moisture will not contact it directly.

In your previous post you though it was too close and getting too hot at 5 feet down the tube? Not at all.. that is a long way down and it should not overheat at all. For comparison the O2 sensor in the 2.2 in my turbo Daytona is about one foot downstream of the turbo in the factory installation. I have the one in the Duster about 24 inches from the head and have had no problems with it.

If your sensor is oriented down on the pipe, 5 feet down, then moisture could be your problem.

By 'oriented down' I mean, with the wire pointing more or less down to the ground, so the sensor tip is oriented up, into the bottom section of the pipe, so running moisture could contact it.

PS. I ain't no scientist (see Dr. Madsen for that) but I do know what condensation is (in my best Forrest Gump.) For real experts on condensation, see these guys: Condensation Experts

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It's a Slant thing. Even I don't understand.

1974 Duster, EFI /6 soon to be turbo...

Get that Monkay! Get that nasty thing!!

Sam from what I have read, an o2 sensor needs to be relatively close to the engine so it stays hot enough to function. Early on the first o2 sensors were one wire devices the relied on heat and oxygen from combustion to generate a small voltage that is measured to indicate oxygen levels.

Later on as these systems became refined two, three and four wire sensors were employed that provided their own heat and ground so that a more constant metering of o2 could be made. By having the sensor independently electrically heated, false readings were corrected from lack of intense enough heat to power a single wire unit.

I forget the optimal operating temperature of these things, but it is around 600 degrees F.

I suspect that your unit became overwhelmed from cool exhaust, and being positioned near the bottom of exhaust pipe where condensation can form when an engine idles for extended periods.

I know when my car idles for a long time during a tuning session, there is a lot of water that dribbles out of the exhaust pipes.

I have noticed factory placement of o2 sensors are anywhere between 9 & 12 & 3 o’clock, and very close to an exhaust manifold terminus.

I’m with Gunpilot, move it closer to engine, and clock it maybe up to 30 degrees off of 12 o’clock in such a way as not to melt any of its wires.

Bill

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

The sensor is above the center line of the pipe, so in that regard it is OK. However it is at the lowest point in the pipe. So it is possible enough water accumulates in the pipe to still get the tip wet. Or maybe it is just vapor condensing.

The manufacturer of these things recommends a wide band be nstalled 18" from a turbo. I imagine this is to protect it from the extreme heat of the turbo itself. The narrow band sensors are apparently not so sensitive to heat damage. My narrow band one was just 6" from the turbo outlet.

I will wait to hear from Lou on this before I move it. I wish to know how far his sensor is from the outlet of his turbo. I think I am on the way now to figuring this out. Sorry for impugning the reputation of Inovate. In fairness they were the ones who kept saying they thought the problem was too much heat, and maybe I should place it further downstream.

Sam

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That is really far back. You want it towards the top of the pipe or at least above centerline, as yours is. For distance back, I have mine 14" back from the turbo, or 25"back from the head port on my NA motors. Maybe mine are too close, but they have given no bad readings.

You could try drilling a small (2mm?) hole in the pipe near the sensor, if at lowest pt. Letting water drain out could help?

Lou

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Home of Slant6-powered fun machines since 1988

Does the sensor immediately turn on (sensor heater) or is there a delay after the engine starts.

One of the problems mentioned with the LC-1 was the hot sensor getting hit with some water. A solution for this was to delay turning on the sensor (60-90 seconds), so all water is vapor by the time the sensor starts getting hot.

Maybe you need to delay turning it on....

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Actually sensor is usually closer to the engine exhaust ports around a foot or so. Even the turbo mopar had O2 sensor about a foot from turbo's exhaust.

Cheers, Wizard

I already have the old Narrow band bung there about a foot from the turbo outlet. The question is, was the Mopar sensor a narrow band or wide band. I suspect it was narrow band. And my narrow band was there for years with no problem. It is the wide band one that apparently is more sensitive to heat.

It would be simple to put the sensor in the old narrow band bung. I am hoping Lou chimes in (he is at a conference in Europe now) with verification of my memory that his is close to the turbo.

Sam

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He did, Sam, three posts up.

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It's a Slant thing. Even I don't understand.

1974 Duster, EFI /6 soon to be turbo...

Get that Monkay! Get that nasty thing!!

While condensation is bad during warmup I don't think that's whats happening here. In the original post you said it had been idling for a long time... any condensation is long gone by then.

The sensor is temperature compensated - it can be located anywhere along the pipe (referring to distance only) as long as it's not too close. For unheated narrow band sensors they can get too cold. For this particular wideband setup that possibility doesn't exist. Think about it - some kits are made to clamp to the exhaust tip.

I believe vapor is ok, it's water droplets hitting a hot sensor that's a no-no. As long as its above the centerline I think you should be ok. Have a pic? That's where the delay-on relays come into play - gives the liquid condensation enough time to become vapor before the sensor warms up. Remember, too long a delay works against you by allowing carbon to build up on the sensor.

The HBX-1 helps guard against liquid water.

Thanks, It was late. I think my eyes go to sleep before my fingers quit typing.

Later Edit:

I went out and measured and the narrow band bung is 8" from the turbo flange. That seems too close. I will investigate putting a new one about a foot or a little more downstream from the flange. The delay relay is something I will look into as well. Thanks for the ideas.

Sam

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