tracy waddell

Thanks again Greybeard, i'm going to try it when i get back from vacation, and install my new custom air intake. I'll let you know what happens.

JoeR

WOW, just WOW!! There is SO much myth, lore, fallacy and false information in this thread I don't just know where to begin!

Let's get started.....

"learn down": The only place I've experienced that is reading this forum! Seriously! DOES NOT EXIST on these cars, period!

Fact: There are ONLY two parameters in the OEM calibration that have a "learn" factor.

1. LTFT (Long Term Fuel Trim): This is a long term average of trimming the AFR to keep on stoic. It is learned over time based on O2 sensor feedback and takes about 80 - 100 miles to settle in. If you "reset the ECM", it will revert to zero and begin the learn process. If you don't reset, it will still "relearn" in about the same time frame and end up with the same result. So... NO difference! The biggest effect on this is changing the intake, which often will effect airflow across the MAF sensor. If the "correction" is within about 18% of target, all is fine, but definitely not ideal. Outside of that, a lean code (DTC P0171) or rich (P0172) will be thrown.

2. KLF (Knock Learn Factor: There are two ignition timing tables in the calibration, high and low. The high is the "target" timing and will work well with the recommended fuel. Say you load the tank with 87 octane... The knock sensor will sense knock and start to factor down towards the low table to eliminate knock and this is proportional. Now, next tank you go back to 93... Sensing the lack of knock, it will begin to factor up.

The above are the ONLY "learn" parameters. Resetting the ECM will do absolutely NOTHING to effect this.

Now for the transmission: All HHRs use the 4T45E trans with a T42 controller. All of the characteristics are hard coded, based upon throttle position and RPMs. There is NO "learn" based upon how you drive.

Hope this informs people and dispels some of the myths I've seen posted here.
Good luck, folks!

sleeper

Thanks for the 411 Joe....

Hib Halverson

FINALLY!
A post on this thread by someone who actually knows how the ECM works.

Thanks "JoeR".

db/sb

Finally? I guess, though it was a month ago. I lost interest in this thread after reading a couple of the posts on the first page and the incredibly obvious and superfluous information, questionable analogies, etc. contained in them in response to a topic that is; for all intents an purposes unnecessary. 3 pages! Good thing I don't use the internet for technical advise. At least, not on automobiles.

SS fan

So Joe...... Why did my car run with 26lbs of boost when I installed the Intercooler and hot side pipes. Then when I started it the second time I was back to 20-21 lbs of boost.

Perhaps I just imagined it ?? I don't think so, it was awesome pull

Vince at Trifecta said it learned it back and the Stg1 doesn't disable that.

db/sb

There are other possible explanations for that involving your boost controller, your blow off valve, or other components in the system but I can see this becomming some kind of internet argument and I don't care to participate in those. Vince at Trifecta also sells 'mail order' tunes. You have more faith in him than I.......

JoeR

Frankly, WTF does the SS/TC Bosch based torque strategies have to do with ANY of the N'A motors????

Simple answer: NONE!