The V8 Owners Forum -

It's a 92 block so I think the test is the 'non CAT':
CO<=3.5%.
HC<=1200ppm.
Which I'm hoping to make ok - but never done this before so who knows. The last car I build was all new parts with a CAT.

Hooked up the Tuner Studio today - it didn't autotune. Turned out I hadn't set the EGO sensor setting to say I have a wide band Tech Edge - lol . At least I think that was the problem.

When I set that all that changes in the msq is:

<constant name="egoType">"Single Wide Band"</constant>

Is that right? Does it send the voltages to the ecu as you change the setting?

Trying again tomorrow.

Mike

If it is just pre 92 non cat test. Then that's a doddle to pass. Wideband should be sufficient as long as its running good and no biggish cam.

seight wrote:It's a 92 block so I think the test is the 'non CAT':
CO<=3.5%.
HC<=1200ppm.
Which I'm hoping to make ok - but never done this before so who knows. The last car I build was all new parts with a CAT.

Hooked up the Tuner Studio today - it didn't autotune. Turned out I hadn't set the EGO sensor setting to say I have a wide band Tech Edge - lol . At least I think that was the problem.

When I set that all that changes in the msq is:

<constant name="egoType">"Single Wide Band"</constant>

Is that right? Does it send the voltages to the ecu as you change the setting?

Trying again tomorrow.

Mike

There are two settings (although this might vary according to the code you're using). <Tools - calibrate AFR table> is where you select your actual one.

O2 sensors will vary quite a bit at idle IIRC for reasons I don't understand, but something like 14:1 at idle and slightly weaker at fast idle should get you through your test.

O2 sensors dont really vary. They will just reflect what they see, and they only measure excess oxygen.

So you cannot compare their readings in any way to a proper gas analyser.

If the engine is running well, no misfires and no big overlap cams, then in general you can assume the wideband's reading will give you a good indication of AFR/CO etc, but that's all it is. An indication.

O2 sensors are very easily skewed, especially by small air leaks or a misfire/overlap ( which basically allows fresh air through the engine...ie more oxygen )
So can often read leaner than you think, and if closed loop is involved, this in turn adds fuel, so you end up with a very rich engine yet the wideband displays leaner than actual

Thanks Dave, so it's:

Tools\Calibrate AFR Table
and
Basic Setup\EGO Control

With the first being done while connected and powered up.
Amazingly, it's fathers day but I'm doing DIY in my daughters room when I should be in the garage tuning my car!!!

Will try this later.
Mike

stevieturbo wrote:O2 sensors dont really vary. They will just reflect what they see, and they only measure excess oxygen.

So you cannot compare their readings in any way to a proper gas analyser.

If the engine is running well, no misfires and no big overlap cams, then in general you can assume the wideband's reading will give you a good indication of AFR/CO etc, but that's all it is. An indication.

O2 sensors are very easily skewed, especially by small air leaks or a misfire/overlap ( which basically allows fresh air through the engine...ie more oxygen )
So can often read leaner than you think, and if closed loop is involved, this in turn adds fuel, so you end up with a very rich engine yet the wideband displays leaner than actual

Thanks. Think what I meant to say is how accurate the O2 sensor is at idle will depend on a number of things. Which either don't apply or are minimal when driving.

As long as the sensor is mounted in the exhaust near the engine, Ive never had any issues with them.

If you mount them temporarily in the tailpipe, outside air can effect them at idle or when stationary, but less so when moving.

Hi,
have a look at my youtube tuning videos, useful if you cant sleep!
http://www.youtube.com/extraefi

Theres a lot of helpful info on my site too, the main thing to check before you go too far is the ignition timing, get that right with a strobe before you drive it!
Phil

Hi Phil,

Yes, I'll do some 'first principles' checks at the weekend. I take it you mean just using a strobe to confirm what TunerStudio is telling me?

Fortunately the timing marks on the pulley actually do line up with the pointer on the timing cover so it's not too hard to check. First pulley I had was a mile off.

Last night's issue was hot starting but I'll double check everything else first before looking into that.

Main thing for me is still that I built my first engine and it bloody works! I wouldn't be able to do any of this without the help of everyone here so a big thank you to all.

Mike