84 3.2 Carrera failed smog, needed new O2 sensor connector and more to get it to pass

[ErrorMargin]

I took my 84 3.2 Carrera Targa to get smogged for the first time with me as owner. I bought the car back in early 2022 and it was time to get smogged (the price of living in California).

I took it in and it failed! Hydrocarbons (HC) and NOx were within the limits, but carbon monoxide (CO) was way above the limit in gross polluter territory. This was a test only station and they had no indication for me as to why it failed.

Here were the 15MPH numbers for my first test:

HC Measured 76 PPM (max is 97)
NOx Measured 67 PPM (max is 804)
CO Measured 2.44% (max is 0.59%)

Here is what I had to do to get it to pass:

Replaced aftermarket DME chip
When I purchased the car, I found the stock DME chip in the glove box and therefore suspected that an aftermarket DME chip was installed. I removed the driver seat, pulled out the DME and when I opened it up as expected I found an aftermarket chip:



Does anyone know anything about this chip? It is a 24 pin chip from "RPM Performance". I put in the original 1984 chip and if anything the factory chip feels like it might have slightly more power??

Connected the brown California DME wire
Apparently all US spec Carrera 3.2 Porsches have a brown wire coming off the DME that when connected retards timing by 3 degrees (not sure if this is for all RPM or just upper range). This was done to meet California emission requirements because retarding the timing reduces NOx. Cars delivered in California have the jumper connected and cars delivered outside California have the jumper disconnected. This is reportedly the only reason why 49 state cars have 207 hp, with a 6.1s 0-60 while California cars have 200 hp with 6.7s time.

My car had the jumper wire disconnected, so I connected it for my retest:



Replaced O2 sensor connector
While trying to verify that the O2 sensor was connected, I found that the car harness connector that the O2 sensor plugs into was broken! This is apparently a very common problem for these cars.

A Pelican forum member, Louie85, used to make replacement connectors but apparently does not offer them anymore.

As far as I can tell, the only option to get a new connector is Kroon: https://www.kroonwireharnesses.com/o2-sensor-replacement-connector-with-high-quality-screened-cable-artno-o2conncable

I bought it on their site and it arrived in just a few days. I took about 45 minutes for me to install.

The Kroon connector comes with all the necessary components to splice the connector into the Porsche wiring harness (solder tubes, heat shrink, etc.). The only tools you need are a heat gun and wire cutters.

The only difficulty installing this is not much slack to work with on the wiring harness in the car where you have to splice in the connector.

Here is Kroon's video on the install: https://www.youtube.com/watch?v=GL8cJ6CJY8o

Here is the broken old connector cut off of the wiring harness alongside the new connector:


Here is the new connector spliced into the wiring harness, you can only see the heatshrink and green wire in this shot, but you get the idea:



After all that, here are my 15MPH passing numbers from the retest:

HC Measured 13 PPM (max is 97)
NOx Measured 3 PPM (max is 804)
CO Measured 0.33% (max is 0.59%)

For comparison, here are the fail numbers again:

HC Measured 76 PPM (max is 97)
NOx Measured 67 PPM (max is 804)
CO Measured 2.44% (max is 0.59%)

Since I had the seat and DME out, I used this opportunity to put in an F9 Tech solid state DME relay with diagnostic lights and pump prime. I'm keeping the original relay in the glove box as a ready spare.

https://www.ftech9.com/new-products/911-ssr-pp

[isby]

Nice work!

[absinthe]

Excellent work on this thread and thank you for all the data and details. I'm still chasing much of this as I rebuild my dad's old car. The "brown wire" Cali spec mod was something I never knew about.