Arjan

Hi,

I have an Euro car without O2 sensor. Last week I installed the LR MAF2 system. I have purchased a 4 wire O2 sensor. 2 white wires, 1 black and 1 grey wire. Now I'm connecting the wiring to the injector A/F meter. I connected the black wire from the sensor to the green wire of the A/F meter.

I like to know where to connect one white and the grey wire at?

I have been told that I can just leave one white wire. I that correct?

Thanks for your reply,

Arjan

Magown

The white wires are for the heater, connect one to a switched 12volt source that powers with the key in the run position, connect the other one to a ground.

Are you sure the black wire is not the ground? and perhaps the grey wire is the sensor output?

Arjan

According to LR:

Black to gauge
White to ground
White to power
Grey to nothing

BTW I solderd the wires and heat shrink. Is this a good thing or not?

Arjan

Travis - sflraver

why are you using a heated sensor? Just use a standard single wire unheated. much simpler and only takes about a min. to get up to heat.

toddk911

How do you know if you 02 is bad???

How are people able to run cars without o2 sensors???

Sami951

Todd, O2 sensor is mainly used to keep the A/F ratio close to stoichiometric, in order to minimize the emissions (and also to keep the cat in shape, I assume they go bad real fast with too rich mixture). My euro spec 951 came without an O2 sensor, because there was no need for one... (I did add one just few weeks ago to hook up my A/F gauge, but it's not connected to the motronic box in any way)

If your car runs too rich, the O2 sensor is probably toasted. There's probably some trick way of testing a sensor, maybe a google search would come up with something? Also if you have an A/F gauge, the display should dither around 14.7:1 on idle and while cruising, switching between rich and lean rapidly ... if it doesn't the O2 sensor isn't working (or is disconnected).

ELLSSUU

Was it only Euro cars that came w/o the O2. Mine is O2less. My 86'.

Sami951

I honestly don't know... I would assume all cars that have a catalytic converter run O2 sensors, and I also thought all US 951s had cats. Anybody know for sure??

toddk911

I understand if cat is out or no need for emmisions tests, you don;t need it, but how does a/f/ get registered?

I mean if your not running a MAF or MAP how does the DME regulate a/f ratios if no o2 sensor??

Travis - sflraver

All US models came with O2 sensors. All ROW cars came without them. The ROW turbos had the bungs welded on the exhaust to accept the O2 sensor but they were plugged. The ROW other cars were not equipped with the O2 bungs.
There may be some deviations to this due to a number of reasons, but that is what I have found to be true.

Sami951

A/F ratios aren't necessary in order to run an engine. Think about carburetors (sp?) for instance, cars with those work just fine and there's no way to adjust the mixture realtime like in fuel injected cars...

The 951's and other fuel injected cars what came without O2 sensors just read the airflow signal (from AFM, MAP, MAF,...) and look up the necessary amount of fuel from the chips (or something like that, depends on the implementation naturally). The only difference is that if there's an O2 sensor, the computer can make small adjustments to the mixture... FR Wilk does a good job in describing how it works, see http://www.frwilk.com/944dme/ -> "Lambda inside"

Travis, guess what - I'm 99% sure my car doesn't have the O2 bung! I double-checked the location from PET, but just couldn't find it anywhere on the car... weird huh! Not sure if it could be because my car just happens to be one of the very first ones, chassis number 79 IIRC ... also some euro cars did have O2 sensors, I'm not sure if cat was an option all the way or if they made it standard in some model year.

Travis - sflraver

Yep, like I said, Thats just from what I have seen so far. Who knows what the true production numbers are and which ones were equiped with the O2 bung/sensor/cat etc... . That is also from what the PET shows so I figure its the running standard.

toddk911

So would it be beter to just un plug the o2 sensor???