'85 911 RoW Oxygen Sensor/DME Question - Page 2

hcubed · 08:42 AM

Be careful with that cat! Because the orange and yellow wires are not hooked up, the box is not regulating the NTS II like it's supposed to, it's possible that you could burn up a perfectly good one if that box isn't working correctly.

I assume you were failing for high HC? That's what I was failing for and the cat won't help. You are failing on HC because the combustion temperature is too high due to the mickey mouse box messing around with the NTS II signal (or, in your case, not have an NTS II signal at all).

These grey market cars, as you've found out, should not have a cat and should not have the mickey mouse box. I have heard that if the box and the cat is removed and the AFM is re-tuned to original, then it should pass emissions just fine (depending on the state's limits).

I think tuning the AFM is only a couple hundred, but you'll want to find a porsche specialist who knows what they're doing to do it. A dealer probably wouldn't even know what to do. My car is in CT (I'm currently in CO) and I was busy getting ready to move out here so never got around to it. I think I will this spring.

So, your steps should be 1) disconnect the mickey mouse box, 2) connect the orange and yellow wires to each other (thereby reconnecting your NTS II signal to the DME as it should be), 3) have your AFM tuned by a porsche/race specialist with an exhaust gas analyzer, and 4) bring it back to emissions.

Then report back here with your emissions results.

tomphot · 02-20-2009, 01:58 PM

I'm going to get into the box when I get back into town next week.
I want to get the AFM back the way it was before the boat ride.
I now have the bypass back on the car and need to get a plug for the O2 port.
I'm really surprised at how well the car ran with the cat hooked up and those other wires cut. Glad I didn't take any long rides and fry the unit.
I found a way around emissions - next year I won't have to worry about it when the hits the magic 25.

Thanks for all your help and starting this thread 4 years ago.

hcubed · 02-23-2009, 08:12 AM

No problem. Let us know what happens with the AFM. I found a way around emissions as well and by the next time I register I will have hit the magic 25...

tomphot · 02-24-2009, 11:31 AM

What is the process for tuning the AFM?
Is it simply getting the CO% within a range?
What is the range I should shoot for?

When at an emissions station - in our state , if you find the right guy, we can set up the machine for diagnosis mode, this will tell you what all the gas readings are. Should we be able to adjust the AFM using a 3mm hex to get the readings thus resetting the AFM?

This same guy also promises I will pass the test - I didn't ask how but am glad I finally found THE guy.

hcubed · 02-25-2009, 08:22 AM

The first thing to do is to see if the spring setting has been adjusted on the AFM. This should be obvious as the black plastic cover for the spring will look like it's been pulled off and then glued back on. Hopefully the federalizers marked the original location. After that, you need to have the car warmed up and running with the exhaust gas analyzer inserted in the tail pipe. You then adjust the AFM with a long allen key to get the correct CO numbers.

I haven't messed with it in a while and I don't remember the numbers. I'm sure they're on this forum somewhere and they're also in the Chilton manual. The exact procedure is probably here somewhere as well if you search for "AFM adjust" or something like that.

hcubed · 02-25-2009, 09:13 AM

Forgot to mention. There is alot of AFM info here from Sal Carceller:
http://members.cox.net/widebody/AFM/AFM3.2LCalibration.doc

renders · renders's Garage

I just came across this thread. I am in the middle - actually towards the end of my engine rebuild - of converting all the electrical wiring back to stock/normal. Long story short I have an original German 3.2 1984 Carrera. I bought it from another German who had imported it and obviously it was undergoing the "let's f*** up this car the best we can" procedure. Today I just removed this woodoo box and tomorrow I will get some 21 ga wire and the connector pin for the DME wire connector to hook up my 3-wire oxygen sensor. I noticed several folks have posted the intention to convert their ROW cars and I am wondering about results and tips - if any.
Anyways my thread is here:
911 3.2 to 3.4 conversion; engine not running
...and it shall continue until it's done

hcubed · 12-29-2014, 09:02 PM

Wanted to close this one off after quite some time. I finally put together a WBO2 2Y2 kit (WBo2 2Y DIY Wideband Unit) with a buddy and used a Bosch LSU 4.2 wideband O2 sensor to analyze the exhaust gas. I ended up moving the AFM spring cog 6 clicks counter clockwise (richer). I never could tell where the original setting was. Moving the spring cog eliminated the surging I was having at light-partial throttle (constant 2300-2800 rpm), but made the idle too rich and it surged on startup idle. I adjusted the AFM idle screw out about 7 turns from all the way in to lean out the idle, but it's still a bit rich. Whatever, these cars weren't mean to idle...

Anyway, at long last, success! In short the steps to de-federalize your RoW 911 Carrera were removing the federalizing box, reconnecting the DME wires back to stock (it's just one wire that needs to be spliced back to itself - see above), replacing the cat with a bypass/test pipe (a bypass pipe with an O2 bung is key for installing your wideband O2 sensor for testing), and adjusting the AFM spring cog and idle screw to get as close to stoich as you can during load and idle.

This will probably not pass emissions in states that just test idle (maybe with states that dyno), but you can always readjust the AFM spring cog to lean the thing way out just for emissions. It'll run like crap, but I've heard you might be able to get it to pass.

Having some sort of exhaust gas analyzer is the trick, and the WBO2 is definitely the cheapest option ($100 without the O2 sensor itself). You'll need some computer hacking skills to get things up and running, but it works well once you figure it out.

Len 911 · Len 911's Garage

Please do not close this , There are still people out there that have questions and you or someone else might help. Like me I have a question, I have an 85 euro and the box I have looks a little different so some advice is needed. My car runs rich all the time ( I can smell the gas ) The box I have has blue , purple, yellow, red , brownand I think black wires. I would like to take this off any suggestions on what to do with this style.

kidrock · 12-30-2014, 08:46 AM

Quote:

Originally Posted by Len 911

Please do not close this , There are still people out there that have questions and you or someone else might help. Like me I have a question, I have an 85 euro and the box I have looks a little different so some advice is needed. My car runs rich all the time ( I can smell the gas ) The box I have has blue , purple, yellow, red , brownand I think black wires. I would like to take this off any suggestions on what to do with this style.

A quick google search shows that unit to be adjustable. There is a .pdf file on Rennlist that explains the Neutronics unit:

https://www.google.com/#q=neutronics+lambda+computer

Len 911 · Len 911's Garage

Thanks kidrock, I would like to remove it if I could. I do not have a CAT but do have an o2 sensor. What are the advantages of removing this from the system

kidrock · 12-30-2014, 03:29 PM

Quote:

Originally Posted by Len 911

Thanks kidrock, I would like to remove it if I could. I do not have a CAT but do have an o2 sensor. What are the advantages of removing this from the system

Well, I didn't go too far into what that box actually is...but if I understand correctly, those boxes were installed to assist in tuning in fuel/air mixture ratios in order to pass stringent smog regulations.

I believe that some of the links showed how the unit is tapped/wired into the DME. If you remove the seat and take the time to see where it has been piggybacked into the DME, it should be pretty self-explanatory.

I would disconnect the battery for sure. I would also do an extra-good job on the wires...the DME is basically the car's "brain", and shoddy work down there can be problematic in the future.

I would also be concerned about what the actual fuel/air ratio will be after the unit is removed. There are many threads here about the use of LM-2 air/fuel ratio meters, or you can have it checked out by a local independent shop.