Picture of my (now coated) downpipe with NPT coupling PO added for tuning the injection system. I will add a gauge someday.
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Jim Gerock
BMWCCA # 381868
73tii "Celeste" # 2764081
71 VW Cal-look Bug

O2 sensor fitting.jpg
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I had a former 73 E3 Bavaria that the PO pulled the stock 3.0L and slushbox, dropped in a 3.3L and 4 speed from a 79 E24 and converted it to EFI. One thing, the PO forgot to wire in the o2 sensor. The car was drinking gas, ran real rich and I couldn't figure out why until I realized there wasn't an 02 sensor in the downpipe and I found the wire that went to it. As MAD 02 says, it's an easy fix at your local muffler shop.

G-Man

Any decent muffler shop will have a box of 02 sensor bungs and should be able to weld one straight to your dp for you in minutes. My friend just had one done for $35.
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1974 2002
1984 Mbz 300SD
1990 Jetta GLI

Gordon wrote:

I had a former 73 E3 Bavaria that the PO pulled the stock 3.0L and slushbox, dropped in a 3.3L and 4 speed from a 79 E24 and converted it to EFI. One thing, the PO forgot to wire in the o2 sensor. The car was drinking gas, ran real rich and I couldn't figure out why until I realized there wasn't an 02 sensor in the downpipe and I found the wire that went to it. As MAD 02 says, it's an easy fix at your local muffler shop. G-Man

Thanks for all the input and the pics. Yeah, this is what's happening with mine. Runs rich, don't feel I get the pickup I should, and no amount of timing, advance, or CO tweaking affects it. I think I will get headers and exhaust, just narrowing down which set up, then add the o2 sensor. Thanks all.

Actually the engine should run very well, just a bit rich without an o2 sensor. I ran mine like that for quite a while before I figured out that I needed a 3-wire o2 not the 1-wire version. When you install the o2 in the downpipe, it is quite far away from the exhaust ports and the non-heated (1-wire) o2 will not heat up enough to work properly. You wil need to install the later 3-wire and hook up the power for the heater circuit.

You should actually be able to tune the engine fairly well without the o2 in place. In fact, when doing any air door adjustments/CO adjustments, the o2 sensor should be disconnected anyway. After the adjustments are complete, hook up the o2 again and you should see little difference in performance. If you do, then your adjustments were incorrect.
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Good Luck,
Mike (#87)

Mike87 wrote:

Actually the engine should run very well, just a bit rich without an o2 sensor. I ran mine like that for quite a while before I figured out that I needed a 3-wire o2 not the 1-wire version. When you install the o2 in the downpipe, it is quite far away from the exhaust ports and the non-heated (1-wire) o2 will not heat up enough to work properly. You wil need to install the later 3-wire and hook up the power for the heater circuit. You should actually be able to tune the engine fairly well without the o2 in place. In fact, when doing any air door adjustments/CO adjustments, the o2 sensor should be disconnected anyway. After the adjustments are complete, hook up the o2 again and you should see little difference in performance. If you do, then your adjustments were incorrect.

It does run well, very very smooth. Before it was terrible, but after doing some tweaking, I got it pretty well sorted. Now, I get a miss on occasion around 2700 rpms. When it happens, it's always in the same rpm range, around the same place on the freeway, so I am guessing it has to do with rpms, temps, and timing, and of course I'm thinking the LJet just isn't adjusting things that last little bit. I've adjusted out all the other issues with surging accel and excessive missing, those were related to valves, ignition timing, rotor/cap, plugs, and fuel pressure reg. Just trying to tweak out that last bit now.
When I say no tweaking fixes it, this miss is what I refer to. Seems to me like the car isn't getting full power, but that could be just my first experience with the 1.8L. One thing I considered were the distributor bushings, as if they are worn they may fux with the impulse generator, but it's pretty predictable so I doubt this is it . . . ?

Thanks for the help.