Smog Test Result Comparison

[Cd]

Not to divert the topic here, but will a grille block lead to 'lean-burn' and higher emissions results, since the engine stays warmer ?

If so, It's coming off.

[ConnClark]

Higher engine temps will lead to higher NOx emissions. The same thing goes for lean burn. I don't know if higher engine temps will cause lean burn however. The computer may actually enrich the mixture to try and bring temps down.

[roflwaffle]

Higher in cylinder temps (lean ratio, timing too advanced) lead to excessive NOx formation. I'm pretty sure intake temps can't get hot enough to directly influence this w/o the front end of the car melting off.

[cfg83]

ConnClark -

Originally Posted by ConnClark

Higher engine temps will lead to higher NOx emissions. The same thing goes for lean burn. I don't know if higher engine temps will cause lean burn however. The computer may actually enrich the mixture to try and bring temps down.

I thought cooling was being managed by the on/off of the electric fan. Doesn't the 02 sensor rule, aka the magic 14.7 AFR (Air/Fuel Ratio), aka closed-loop operation? I know it's more complicated than that, but I think this captures the majority of driving conditions, especially because of the way we drive as Ecomodders.

I agree with roflwaffle that a WAI is not "lean burn" per se. I liken it to driving in Death Valley. Less oxygen per volume of air, so less fuel per volume of air (right?!?!?!). I would claim we are simulating operation in an "extreme zone" of the ECU/PCM. This would contribute to the different reactions by different cars. Depending on how the ECU/PCM was programmed, the engine would like/dislike the WAI.

Maybe this discussion deserves it's own thread ("Does a WAI/HAI increase emissions?"). Same for a grille block.

CarloSW2

[Christ]

Carlos - I think what Clark is trying to say there, is that depending on the situation, your ECU may periodically dump fuel to cool down the pistons, if the ECU thinks that you're running too hot for too long a time. You'd have to monitor/record real-time AFR to figure that out though... or look for a spike in injector duty.

This seems plausible, because dumping fuel is a common way to cool internals in an engine (wasteful, but it works faster than waiting for the radiator to do it.)

Maybe the WAI in combination with the grille block puts you right on the line, and it's possible that you're going over the ECU's "safe limit" once in awhile, and it might be dumping fuel thinking that you're heading for catastrophe, as a way to cool it down and prevent meltdown.

You might consider watching your temps, O2 output, and injector pulsewidth with something that you can download a timed map of them, and compare the signals, looking for spikes in each, and how the signals correspond with one another. You just might find where your "sweet spot" for temperature is, then you can make a CAI/HAI hybrid that will allow you to maintain a given temp more accurately, keeping you on the threshold, but not "in the house", so to speak.

[cfg83]

Christ -

Originally Posted by Christ

...[stuff that makes sense to me]...

You might consider watching your temps, O2 output, and injector pulsewidth with something that you can download a timed map of them, and compare the signals, looking for spikes in each, and how the signals correspond with one another. You just might find where your "sweet spot" for temperature is, then you can make a CAI/HAI hybrid that will allow you to maintain a given temp more accurately, keeping you on the threshold, but not "in the house", so to speak.

I have a real-time digital AFR, so I can see the 02 sensor in action (but no data logging). Once it's warmed up, it almost never goes richer than 14.5 at any time. If anything, I see the ECU/PCM trying to "cheat lean". I often see it go into the mid 15s before popping back to 14.7 +-0.2 oscillation. I use the SG to monitor coolant and IAT, but I can't see injector pulsewidth. I don't know how to interpret the ignition timing parameter (IGN).

I think I understand what ConnClark is getting at, but I am trying to make the distinction that I am not driving normally. I am attempting to drive like an Ecomodder/Hypermiler, keeping the load on my engine as low as possible. This is why I think closed-loop operation dominates my driving. I think the only time I put the car under heavy load is when I accelerate to merge onto the freeway, or under emergency avoidance. There is only one other "high load" condition where I drive up a 4% grade the last mile to my house. I almost always run the electric fan (I have a manual override on/off switch).

CarloSW2

[Christ]

Ok, I just thought I'd clarify and add a few points to it.

It couldn't hurt to "push the limit" a little bit, and find the optimal operating temp for your engine, optimal intake temp, etc... and then find some combination that satisfies them.

Good luck!

[Cd]

Sorry for diverting this thread .

Back on topic ?
...please ?

I'll post my results when I get around to it.





This in no particular order, and my latest results are misplaced.
Let me know if the images are too small.

[Cd]

So I had the impression that hybrid owners had to do a seperate emissions test, because the motor doesn't kick in till later. Is this true ?

[cfg83]

Cd -

Originally Posted by Cd

So I had the impression that hybrid owners had to do a seperate emissions test, because the motor doesn't kick in till later. Is this true ?

In your case, the 15 MPH and 25 MPH tests appear to keep the engine running. Because the car is connected to the OBDII port, I'll bet they can signal a hybrid to keep it's engine running anyway (that's what I'd do).

PS - It would be nice to know the date, mileage, model, and your of your car for the tests you posted.

CarloSW2