mixture control

[hipdoc]

Wow, so many knowledgeable porsche buffs. I really like the Zeitronix set up. Where do you put EGF and O2 lamba sensor in a 79' 930? Do I need to take out my exhaust system to tap in a hole for these sensors? Is it pretty tough to install? I guess I have to first ask the boss, my wife, if I can get one for Xmas - I'll have to do the poor man version for now. But a quick clarification, do you put the 3mm Allen into the spring loaded post (access screw) or need to take that out and then use the Allen? Thanks, hipdoc.

[9dreizig]

Hip,
There MAY be a plug in the post there was on my 86,, just pry it out as I recall.
Depending on the exhaust system you have you may have to drill and weld an O2 in ,, Unless you don't have a cat then you can just hang it in your exhaust...

[Chuck Jones]

Bryan: You did give me a bit of a start there for a minute....you said "dropped his car" so casually that I thought....I wonder if he scared the dude off....

I have the LM-1 and sensors if you need them down there...I can UPS it down for you to do the settings then send it back if you want. All you need is a bung. Er....for you Britts, that's a fitting for the sensor...

[356-930]

Originally Posted by hipdoc

Where do you put EGF and O2 lamba sensor in a 79' 930? Do I need to take out my exhaust system to tap in a hole for these sensors? Is it pretty tough to install? But a quick clarification, do you put the 3mm Allen into the spring loaded post (access screw) or need to take that out and then use the Allen? Thanks, hipdoc.

Below, photos of location of 2-EGT sensors and O2 sensor installed.
Fundamentally, get the EGT sensor as close to the turbo as practical, certainly past the junction of the two headers.
Locate the O2 sensor as far away from the turbo as possible and B4 the cat converter.
Re: 3mm allen access to 3mm mixture adjust screw, the spring loaded access screw posted earlier is custom. The stock access screw is a large headed allen screw with a copper sealing gasket. Yes, you need to remove the 3mm access screw/washer to access the 3mm adjusting screw, straight down through the access hole. Remember, seal this hole with tape or something to check AFR when idling, it's a huge air/vac leak.

EGT Sensor B4 Turbo


O2 Sensor away from Turbo, B4 Muffler (and B4 Cat if you run one.)

[9dreizig]

356, I always thought the o2 should be after the turbo, yours is before the turbo?
Todd

[356-930]

Originally Posted by 9dreizig

356, I always thought the o2 should be after the turbo, yours is before the turbo?
Todd

O2 definitely after and as far away from the turbo as practical, B4 the muffler. My exhaust is awkward in appearance due to space constraints. The turbo discharge is to the left and out of the photo.

Here's a photo without the waste gate discharge pipe installed that shows the muffler/O2 sensor more clearly.

[rsrmike]

Man o Man 356, I can never get enough pics of your work!!! Note, if your o2 sensor ever pukes, you may have to move the "bung" where the sensor isn't upsidedown.

They say that exhaust condensation will collect in the sensor and fry the heater circuit... Although considering the amazing feat you have pulled off, there probably isn't room to put it anywhere else and you probably already knew that!!

[356-930]

Originally Posted by rsrmike

Man o Man 356, I can never get enough pics of your work!!! Note, if your o2 sensor ever pukes, you may have to move the "bung" where the sensor isn't upsidedown.

They say that exhaust condensation will collect in the sensor and fry the heater circuit... Although considering the amazing feat you have pulled off, there probably isn't room to put it anywhere else and you probably already knew that!!

Mike:
Thanks for the kind comments.
Yes, the sensor will die from condensation, should be mounted between 10-2 o'clock. You are right, because of the need to get as far away from turbo as practical, it had to be installed at the wrong angle it could be remove, a necessity to be able to remove the exhaust pipe/muffler assembly when needed.
Fortunately, a new O2 sensor costs less than $100. I tell myself it's an expense item in the grand scheme of properly maintaining a 930 engine.
Chris

[rsrmike]

Hey Chris,

I figured as much, I just had to say it before someone else did!!

Sounds completely logical, funny enough, they die for numerous reasons all the time anyways, so being easier to change is probably a good thing!

[A930Rocket]

Mine always seem to die at the track pulling hard out of pit out. Not sure if it's the boost, rich condition or what.

...they die for numerous reasons all the time anyways, so being easier to change is probably a good thing!

[billjam]

Originally Posted by 356-930

O2 definitely after and as far away from the turbo as practical, B4 the muffler.

Why before muffler?
After muffler is cooler and it is much easier to have O2 sensor in top half of pipe.
I was planning to fit sensor in the tailpipe after the muffler so that it is vertical and between the two turbo housings (but closer to the cold side of the turbo). The lead would run easily through a hole in the sheetmetal directly above the sensor.
I don't have a cat to worry about.

[hipdoc]

356-930, that's an awesome set up!!! I guess I would need to remove my exhaust system to weld in bung to fit these sensors. What other types of sensors are needed for the Zeitronix? Also is it worth putting a EGT sensor for another 930 engine I'm putting together that has a Electromotive Tech 2 system or is it worth using Zeitronix with the Tec 2? Alan

[356-930]

Originally Posted by billjam

Why before muffler?
After muffler is cooler and it is much easier to have O2 sensor in top half of pipe.

After muffler is indeed cooler and ok too. In my application, I didn't want the sensor sticking out from under the bumper as the end of the muffler is within an inch of the rear valance.
The dyno tuners stick an O2 sensor in the exhaust pipe after the muf, has to be ok.

[356-930]

Originally Posted by hipdoc

I guess I would need to remove my exhaust system to weld in bung to fit these sensors. What other types of sensors are needed for the Zeitronix? Also is it worth putting a EGT sensor for another 930 engine I'm putting together that has a Electromotive Tech 2 system or is it worth using Zeitronix with the Tec 2? Alan

You will have to remove either the exhaust header that bolts to the turbo or remove the turbo, add the O2 sensor bung to the in-place header. Keep in mind, you need to remove any cutting chips and/or weld spatter from the header so it won't eat the turbine blades. As to the O2 sensor, cut/weld the bung with exhaust in place. Any junk left in the exhaust pipe will do no harm. This said, I would not recommend cutting and welding the bungs into the exhaust system while any of it is in place. A lot safer if one removes the exhaust and adds the sensor bungs.
I know nothing about the Electromotive Tec 2 system. If it has data logging software, you shouldn't need both the Tec 2 and the Zeitronix. For the Tec 2 to operate I presume it utilizes various sensors that would replicate sensors used on a data logger from Zeitronix or Innovate. Perhaps someone who knows what they're doing can weigh in here.

[9dreizig]

Billjam, I put mine right in the muffler in front of the bumper, lot's of room and really easy to get to..

[Chuck Jones]

Biljam: I just had mine welded into the exhaust pipe right after the muffler...but was looking at all the room there was on the flat back end side of the muffler and was wondering if anyone had ever installed it right on the muffler itself....lots of room for wiring, and less heat than there would be right on the outflow side of the muffler pipe next the turbo.

I'd be interested in hearing how your setup works....becaue this is the first time I've read of anyone installing it in the muffler itself. Sure looked like a good spot to me, but all the threads I've read talk about the install right after the muffler on the pipe in the 10-2 position.

Since I dont' intend to leave it in as a permanent fixture, I put the bung in the 8 oclock positon for ease of access.

[rsrmike]

Not to be a total pessimist, but keep in mind, the above shown style of muffler is prone to cracking, as they are normally built from thin walled 304 stainless. After a while, the heat and vibration takes it toll and the muffler develops small (or large) cracks.

I can't tell you how many Borla turbo mufflers I've had to repair, along with other brands of the same build type. Granted, a cracked muffler would likely indicate a lean condition, if it was sucking air, and most likely leak worse under decel (where AFR is of no significance) but something to consider none the less.

I would just keep an eye on the muffler from time to time and do your best to install at least one, maybe 2 support straps to minimize vibration and flex over time

[Chuck Jones]

rsmike: It was the thin gauge of the 304 stainless that made me decide to go to the muffler pipe...but I was close to putting it on the end of the muffler itself...your post makes sense. However with a muffler, the leak is usually easy to spot either thru the sound of the leak or an exhaust stain where it's leaking. It seems to me that as long as the bung was installed correctly, and you check it every so often for leaks, it still might be a good place to put the sensor. I'm sure the experts will chime in...

[mark houghton]

On the topic of where to put the bung for an O2 sensor to support AFR readings, see the link to Rennlist http://forums.rennlist.com/rennforums/showthread.php?t=443682
You don't want the sensor to get too hot (like right after the turbo), nor do you want it installed too close to the tail pipe (for fear of fresh air getting mixed in with the exhaust). The discussions in the Rennlist link speak to several options.

[gogomobil]

what happens if the AFR sensor is installed before the turbo?
wrong readings? or will the sensor be toasted?