02 bung welded, ready to resume MPS tuning Options

[rfinegan]

I had a little free time to day so I decided to add(weld) the O2 bung to my Bursch exhaust

wide band O2 is now ready to go....

[rfinegan]

And Plugged when not in use...

[pbanders]

Forgive my ignorance, but exactly what kind of tuning are you doing? If you're using a stock 1.7 or 2.0L motor, and the correct D-Jetronic components, and they're all in working condition, the MPS does not require any tuning.

What motor do you have, and is it modified? The MPS can be adjusted to set the mixture/CO/AFR for part-load, and also for full-load and the onset of transition to full-load operation. Idle condition mixture is set with the knob on the ECU. Engine speed correction (pumping efficiency) adjustment is more complex, and requires modification to the multiple waveform shaping circuits on the ECU daughter board.

With regard to using even a wide-band sensor with your exhaust bung, you will likely only be able to tune accurately for part-load and full-load operation. Idle condition tuning requires a CO meter that reads in the range from 0 to 5% (or an AFM range of 12.5 to 14.5). Maybe wide-band sensors are better now, but I believe they have accuracy problems in that range, because the O2 curve in that range is very flat and low signal. You might be better served by going to a tuning shop and using their dyno and pro 5-gas analyzer.

[Ishley]

I also welded a wideband sensor into my Bursch. It's very helpful for tuning. You can really dial in the MPS with the AFR and get it right in the range you want. I do not have any issues with idle data sensing and capture. I put it basically in the same spot as you did.

My original gauge and kit was a Chinese knockoff... AEM kit. It worked fine... except when I went to wire in an RS232 so I could log data to my laptop... it wouldn't work. So I bought the real AEM kit... and only had to change out the gauge... all the wiring etc is the same. It works perfectly and now I can stream data onto my laptop easily.

I also have a 123 + distributor... with Blue tooth. This version of the 123 will create a log file... which I simultaneously log along with the AFR/OS data. Post run.... I bring it all into spreadsheets and can graphically view that data.

The data elements of advance, vacuum, rpm, speed, temp, AFR, etc... allow you to view engine load conditions and how the Air/fuel is changing... A few tweaks on the MPS... and you can really see whats happening... improvements and compromises along the range.

I'm planning to write some Python code to simplify the process and get it all to not only log but crate a viewer realtime.

[rfinegan]

Yeah, I had a leak in my MPS 2.0 diet and a new o-ring fixed the problem, Just need to set the full load stop and I should be in close enough ...thanks for the tips

[Ninja]

Excellent spot!

The only times I've had O2 sensors screw up was at idle (as pbanders mentioned) but that was running the sensor (5 gas none the less!) at or near the tail pipe opening.

The exhaust can run negative pressures and actually suck air UP the tail pipe.

That muffler just past the sensor will stop that from happening!

Now, ANY exhaust leak can have the same result, you just notice the dilution more at idle /low flow conditions.

In my book the most important gauges to have are oil pressure, temp (for the 914 a CHT!), and the wideband.

I'd fix a wideband before I fixed a tach...

Even if you cannot adjust your system, you will know something is wrong!
(IMG:style_emoticons/default/ninja.gif)

[pbanders]

Yeah, I had a leak in my MPS 2.0 diet and a new o-ring fixed the problem, Just need to set the full load stop and I should be in close enough ...thanks for the tips

Ah, I thought it might be that. Should work fine, good luck.

[emerygt350]

For tuning I found it very helpful to have a vacuum gauge but if all you need to do is WOT and the full stop you should be fine.

[rfinegan]

Seem like its leaning out under load...either MPS setting or drop in fuel pressure, shows high head temp when this happens

more on the fuel system shortly, as I button things up under the tank