I've owned and modded 2 Chrysler 2.2L turbo cars, a Lazer and a Lancer, and now a supercharged Buick, and there are a lot of ways to run reliably, leaner:
Intercoolers,
More efficient exhaust/downpipes,
more efficient turbos/housings,
lower "static" compression,
more efficient combustion chambers(smoothed),
more efficient camshafts specifically for boosted motors,
better PCM spark management,
cooler plugs,
better fuel quality and octane,
and more...

 

And that reason is?

 

Probably because it's impossible to run closed loop at WOT unless you swapped to an aftermarket ECM with WB feedback in an OBDI anything. There's not a lot of point in replying to someone who obviously doesn't understand some/all of what closed loop means, and what narrowband O2 sensors are good for.

 

Yes you are right... but all things being equal, the AFRs is what holds the engine together at the end of the day. And for a production car running NB sensors, the only way to run efficiently would be to run the correct mixtures. Running too lean creates hot spots. You cannot take the physics and chemistry out of the equation, no matter how much plumbing you add to your engine... short of adding direct injection which burns fuel more sparingly than normal MPFI.

Anyway, I'll leave this topic alone and hope the GTR topic will continue with minimal interruption from this point onward.

 

I know full well what all of those things are.

A 1987 Grand National does not use an OBDI system; that particular standard had not been created yet.

I have a scanner that hooks up to the ALDL port on the car. One of the scanner's outputs is an indicator that tells you when you're running in open loop and when you're in closed.

I have watched the scanner tell me I'm in closed loop at WOT many, many times. I was surprised to learn it the first time too, but it's true. The only time I've seen it run in open loop was when the O2 sensors weren't warmed up yet.

I don't pretend to know how it does it, but the fact is, it does it.

 

I think of everything pre OBD II as OBD I. The small changes that came in the later 'OBD I' standard are hardly noteworthy in GM cars. Even the earliest GM computer controlled cars had on board diagnostics capability, and the early 90s ECMs weren't much better then the 1983 ceasefire ECM at giving you useful information, hell the majority of the DTCs were unchanged, just a couple new ones added. I've pulled code 32s out of every flavor of early GM ECM you can name for example, starting with an 82 ceasefire and 83 CCCS

But to the real point, your scan tool is confused / lying or you're misinterpretting it (i.e. BLM is active, superseded by PE mode but the closed loop flag doesn't change, it's been 4-5 years since i've used datamaster/scanmaster on an earlier car). Rest assured though, it is *IMPOSSIBLE* to be closed loop at WOT. Easy way to see this, look for O2 cross counts, you won't get any. STFTs should also go flat/zero.

Here's a remedial explanation, closed loop means feedback from the O2 sensor is being used to adjust the AFR. Narrowband O2 sensors are *NOT*accurate as anything but switching devices around 14.7:1. A turbo engine would melt down in no time under boost at 14.7:1, therefore the narrowband feedback is useless, therefore the loop can not be closed. Period.

Exactly why do you think people who tune use WBO2 sensors and why some cars even have them stock? You think they just like building in extra expense for fun?

If you don't understand how it does it, then you've proved my guess as to why the other guy didn't even want to respond because your first post established you didn't know how it works. I'm done with this hijack, if you've made it this far in life without a clue as to how EFI works, i'm not going to be able to teach you with a few paragraphs.

 

I'll concede that's possible. One of the readouts is labeled "Loop Status", and I've seen it read "OL" and "CL". The manual indicates that those are Open Loop and Closed Loop, as you would expect. The scanner displays "CL" at WOT, and that was the only basis for my claim.

I know all of that. That's why I was surprised.

No, I think they like actually tuning their A/F ratio.

I'm certainly no expert (and it sounds like you might be), but I'm pretty familiar with how EFI works. I don't know what your comment about "made it this far in life" is supposed to mean.

If you are willing to throw a few more paragraphs my way, I'd be interested to learn more about BLM. My scan tool has a readout for it, but I don't know how to interpret the numbers.