Danno

"Anyways, where do you guys tap into for the gauge? I know boost usually goes to the KLR, and I'm wondering if there's something closer than the o2 sensor itself... TIA!"

I've got a detailed step-by-step procedure on my 951 RacerX website. It's under the ARM-1 installation. You don't actually need to get as complicated as extracting the connector pin out, you just scrape away some insulation from the O2 signal wire and solder your gauge to that. You can also pick up power and ground at the DME harness as well.

The reason I like to tap into the DME-connector is that you're guaranteed the same signal that the DME sees. There's a reason Porsche used a coaxially-shielded cable to run the O2-sensor signal into the car. Low signal-strength from the O2-sensor is one and maintaining a fixed impedance with a coax-cable helps the signal get to its destination. The other is interference in the engine bay from spark-plug wires and the coil. Without shielding, the O2 signal is bound to pick up interference along the way.

That, or the other thing could've been I was lazy and didn't want to run any more wiring than I needed (especially through the firewall). So I've only got a short 60-70cm length of wire used to install my air-fuel ratio gauge... saves weight too...

rhesus

Thank you sirs

Bri Bro

DangerIsland

I do believe the 944 DME sold for use in Europe didn't use the O2 sensor or have a CAT. Maybe some from the other side of the pond can expand on this.

Danno

That's correct. The non-US cars didn't have cats and O2-sensors. The DME was switched over to the ROW fuel-maps using the impedance-adaptor on '86-87 models and the region-coding plug on '88+ cars. The ROW fuel-maps have to be more precisely matched to the actual air-flow conditions since there's no corrections based upon O2-sensor feedback. The USA maps tend to be 5-10% richer and I suspect they were just relying on the O2-sensor to fine-tune mixtures. Running a USA car with the O2 disconnected and using the USA maps would probably end up being to rich. But if you've got flow-increasing mods, certain areas of operation may end up too lean as well.

newkie

Im about to put in a new O2 sensor. And and then i found this thread. Now i dont think i will solder it :P I can't however seem to find the document you mention...

Van

Holy blast-from-the-past.

KuHL 951

Holy Danno...yes this does go back a ways. It's one of the first posts I read as I eeded a new O2. I use crimps, never had a problem.

F18Rep

Show me a tecnician that use pinch splices and I'l show you one that creates more problems than he solves. Nick the insulation below the splice (a pin hole) if you're really worried about a few molecules of reference air. To each his own...;] Bruce

Bob Rouleau

FWIW - good practice for boats, cars and aircraft is NOT to solder but to use mechanical connections which handle vibration better than brittle solder. This may explain the Bosch stipulation to not solder the sensor wires.

JohnKoaWood

Solid wires MUST be soldered this goes for on ships and Aircraft as well... everything from Jet Rangers to U-2 have used solid core wires soldered, not crimped.... Can't tell you how much re-work is performed annually because of the mis-conception...

Bri Bro

Strained is what is used in most auto wire since it can flexed many more times without breaking then solid wire. Remember, strained is solid wire braided together. Every terminal has its requirements, some are designed to the soldered, other crimped. Most terminals on a Porsche use stranded wire that is crimped.

Now, back to O2 sensors, their instructions recommend that you crimp the connections if splicing the wires. If you don't know how to crimp, purchase the complete O2 sensor and save yourself the hassle.

Now to Bobs comment, soldering strained wires. Once solder is applied to strained wires, it makes a solid wire that can not flex and will break at the junction of the solder and the strained wire if flexed. There is no easy answer to this question of solid wire, strained wire, crimp or solder. You need to determine the the environment of the application and the requirements of the equipment.

marky522

Just FYI as to Porsche's Point of view on this, We as technicians are directed on all "High importantnce" Connections such as airbag, ABS etc to crimp using there special crimping tool where the crimp grabs the wire and grabs the insulation for support. Porsche's view is that 1. soldering is too inconsistant from one tech to the other... I have seen somone heat the two ends individaully apply solder stick them together and reheat to flow the solder, I have seen his joints break on occasion. 2. As was said above a change in resistance in the circuit, may not be SO important in the 944 series but in the newer cars this is HUGE.

Mark

anders44

my 1986 european turbo came without o2, and without cat. in 87+ they have both.

Jusii

My 1986 turbo came with cat and 02 and it was made for german market. But I think the buyer choose that as an option because in germany you got some tax reductions for low emission cars.

eniac

If you know how to properly solder then it's fine to do as long as you solder as far away from the O2 sensor as possible(at least 12" away). If done properly it will not add to the resistance of the wire anymore then a crimp connectoror or a plug, chances are it will have less resistance. I learned to solder when I was 8 years old and have seen way more crimp connections fail then I have seen good solder connections fail....come to think of it, I have never seen a good solder connection fail.