Bill.e1

I've had my 944 for about 2 months now. Much of that time, I've been chasing niggling drivability issues. I did the standard stuff (compression, plugs, wires, vacuum, connections, pressures, meters, Techron, etc) plus whatever unique issues I found on the net. I bought every book I could find on Bosch injection systems. This all helped but didn't cure the big issue- surging during medium acceleration and 'soft' maximum acceleration.

One day I saw a Sunpro O2 meter on clearance at the local parts chain. I figured for 20 bucks, it might help. I originally connected it to pin 24 at the DME. I found the weak portion of the acceleration surge corresponded to the max lean spike in closed loop. It seemed to stay in closed loop unless the throttle was truly floored at WOT, the reading was steady but leaner than expected. I didn't take this too seriously since these guages are not very accurate.

The point? While a wide band would have told me more, the narrow band is useful compared to nothing.

Anyway, I bought a new O2 sensor but, after looking at FR Wilk's page, I think the one I have is OK. I thought about using the fuel quality switch and even made a tool for turning it. Then one of my net searches found a reference to some secret ritual that, if properly performed, would activate the ROW fuel maps. Key to this ritual was mythical Porsche artifact called a "codes plug."

That was a week ago. Since then I've scoured the internet, looking for the clues. While I found several posts describing how to change maps, none of the combinations worked.

Two days ago, I found the "Rosetta stone"- the key I was missing. On an official Porsche 924S wiring diagrom, they showed pin 24 (O2 sensor in) grounded for ROW applications. For my car, a 1986 NA, the Euro map is used when pin 10 (codes plug) is grounded, the altitude compensator is replaced by a 1.8K resistor (I used a 5k pot and adjusted it to 1.8k) and pin 24 is grounded.

Unfortunately, this configuration also disabled my O2 meter. I ended up cutting the sensor signal wire on the sensor side of connector, grounding the pin 24 side, and connecting the meter to the sensor side. This way the sensor heater still works. The meter shows full lean (best economy) most of the time but moves up the the ideal/rich cutoff point under power. The car runs great.

Some very big caveats- as far as I could tell, the code plug usage varies by year and model. Also, the official schematic for an 86NA was innacurate- it was only when I added the later 924S info that the car changed maps. I don't seem to have hurt anything using invalid combinations- it activates the limp mode and your car runs worse. Obviously this was all done off the highway since it is unlawful to drive a car with altered emmisions controls.

Is a wide band better? I am sure it is. But for 20 bucks, a narrow band will identify glitches and transisions. In the land of the blind, the one-eyed many is king.

Hope this helps, sorry it's so long.
Bill
86NA

DanG

You know whats crazy about wide bands though? The Innovate Motorsports LC-1 costs $199 new, for controller and sensor, then you can replace sensors for just $45 shipped! Thats cheaper than a Bosch universal 4-wire NB sensor. They're VW 1.8T standard parts, so they're made in large enough quanities that the cost can stay low I guess.

The LC-1 is fully programmable, and can be plugged into a WB-capable ECU while simulateously outputing a "narrowband" signal to a standard A/F gauge. Or it can just output the calculated NB signal directly to a NB ECU, although that pretty much defeats the purpose.

I've got an LC-1 on order now.

Fishey

Yea, So why doesn't anyone make just the wideband reader? You have to buy both the O2 senor and the Reader I know this is a disapointment to many 1.8t guys that should beable to use wideband for cheap (very cheap)

Danno

You need an active controller to make the wideband work... it doesn't just output a straight voltage vs. air-fuel ratio.. And the controller has to be calibrated for the exact WB sensor you're using. Unlike the flip-flop standard O2, teh WB units have vastly different curves... The NTK is not the same as the LSU...

BTW, the ROW maps tend to be much leaner than the USA maps. The US cars by default are rich and requires teh O2-sensor to provide feedback to lean out the mixtures.

DanG

That same controller/sensor combo is available as just the controller for $150.

http://www.innovatemotorsports.com/x...cat=253&page=1

Although I'd think any of the 1.8T guys chips would already be WB capable (or even require it), so they really wouldn't need a stand alone controller at all.

OriginalSterm

i used my narrow band O2 monitor to quickly pick up on the fact my O2 sensor had failed. No matter how much gas I gave it, the monitor always showed 1 red LED.

I'm saving for a wide band, so my narrow band monitor is for sale cheap!

Geo

Excellent and informative post. However.... while you have some success, I would not make the blanket statement that a narrow band can always identify problems.

I've posted this before, but a good friend of mine who is an automotive engineer and aftermarket industry consultant was helping a friend of his tune his turbo car on a dyno. They just couldn't get the car to put down the power it should. I cannot remember why, but they initially didn't use the Horriba (WB) at the dyno place. The guy's AF gauge (narrow band) said the car was good for mixture. However, when they decided to try the Horriba they found that the car was runnign so dangerously lean it was a miracle the engine didn't blow up.

I'm not trying to take away from your experience, but it doesn't mean everyone will get lucky.

Geo

Interestingly enough, the maps on most cars are on the rich side and power is made by leaning them out. Most people think you add fuel to make more power, but quite often it's very much the opposite. OEMs like to run rich because it's safer. It keeps the engine cooler and less chance of detonation under extreme load. I image the newest cars however are running leaner than ever for emissions resasons.

Bill.e1

George,
I agree that the narrow band has little value to a true "tuner." However, if your goal is to troublshoot a mostly factory system, it offers a lot of value by showing you the lean/rich transitions. In particular, I found the ability to visualize closed loop is useful. On my old 84 Vette, jumping two diagnostic port connectors made the check engine light track the O2 sensor interupts- on for rich, off for lean. Every little bit helps.

Personally, I think much of the narrow band's bad reputation comes from the fact that the signal is extremely low current. It took me two or three attempts before i was satisfied that I was seeing true signal, not artifact or noise from the meter or other connection issues.

Have fun,
Bill