Extender fueling & "Learn"

[Dean]

I have been using Extender Chips for years now (since back in the Translator days, before T+) and have a question on how something works. I use Direct Scan.

When I go WOT, like on a 1/4 mile trip, what happens fueling calc wise? My Cell 15 is 121, but at WOT the BLM & INT readouts go to 128, and "Learn" goes off. As I understand, the ECM only uses O2 sensor data for updating fueling requirements when the Learn function is enabled, so if it is disabled, what is the Extender doing?

I have seen BLM lock at WOT advertised as a feature "For more consistent full throttle fuel control", but isn't that negating the selling point of the Extender? I'm not knockin' the Extenders, I'm just a bit confused.

TIA!!

 

[TurboDave]

I have been using Extender Chips for years now (since back in the Translator days, before T+) and have a question on how something works. I use Direct Scan.

When I go WOT, like on a 1/4 mile trip, what happens fueling calc wise? My Cell 15 is 121, but at WOT the BLM & INT readouts go to 128, and "Learn" goes off. As I understand, the ECM only uses O2 sensor data for updating fueling requirements when the Learn function is enabled, so if it is disabled, what is the Extender doing?

I have seen BLM lock at WOT advertised as a feature "For more consistent full throttle fuel control", but isn't that negating the selling point of the Extender? I'm not knockin' the Extenders, I'm just a bit confused.

TIA!!

Yes, learning is disabled at WOT, but remember the extender can still deliver proper fuel levels based on the fact it is no longer limited by the MAF's 255 limit and is able to properly meter.
I don't know the programming behind the scenes, but basically it's halving what it sees from the maf, making fuel calculations based on that and then somehow doubling everthing before sending the fueling commands to the injectors, etc.
And of course there's a LOT of other stuff going on in the background to make it all right.

 

[Dean]

Thanks for the reply, Dave. OK, my thinkin' cap is back on, but it is old and dusty, so bear with me...

I get how the MAF #s work (halved), I just though the BLM Cell 15 would be considered as well, in conjunction with the O2s. Cell 15 is the high load cell, which *should* be the most accurate since it is closest to real WOT. I guess I am just surprised that all learning is ceased, and all that was learned is disregarded. And then without the O2s, how does the ECM know if the propor fuel levels are being administered if the data is disregarded? Just seems strange.

I guess that is why we have WOT fueling to play with.

Dean

 

[TurboDave]

Yes, cell 15 is considered. Remember, it takes very little load/throttle to get into that cell, even though it's usuall refered to as the WOT cell. Cell 15 will still learn before WOT conditions are met, and it contributes based on it's learned value.
As far as O2's being ignored during WOT, yes, the system HAS TO!!! Remember, the O2 sensor is a narrowband switching sensor, and is only going to be accurate at or very near stoiceometric A/F ratios of 14.7:1. Any values outside that and the readings cannot be trusted to be accurate and are extremely non linear in nature.

The only real solution to WOT fuel accuracy beyond what exists (maf flow values and learned BLM values) would be a wideband O2 sensor.

 

[Dean]

Thanks again, Dave.

Is Cell 15 considered and a contributing factor at true WOT (not simply 1500+ rpms / 30+ gps), though? According to my DS files, it looks like no... the BLM & INT go 128/128 on all my files. Do you have any files that indicate otherwise? (Side note: I recall seeing files of yours years ago showing a dang near flat 1/4 mile O2 "curve", and being duly impressed. I have yet to achieve that.)

I'll qualify the following by stating up front that I know virtually NOTHING about chip programming.

If the above is correct on the BLM/INT, it seems that an Extender is basically programmed similar to a conventional chip (with fueling tables using a forced 128/128 basis?), but with additional programming taking the MAF reading into account to do a better job at the fueling estimation. Better than conventional, no doubt, but user tweaking is still required in the same manner as a conventional chip, since the system still wouldn't know if the fueling is anywhere near correct. The main difference for me is that the tweaking is done electronically with the Translator, rather than with the boost rod & FPR. The only remaining issue is that once the settings are made, still no corrections will be made if you start going lean or rich.

BTW, I'm not bashing the Extenders. It is all I have used for years now, and something I continue to recommend. I am just trying to get a better understanding so that when I do make it a recommendation that I can better explain the whys and hows. I don't know how Bob does to make these chips work as well as they do, but I suppose that is where a broad range of experience pays off. Literally.

Thanks again for your time,

Dean

 

[turbojimmy]

Yes, learning is disabled at WOT, but remember the extender can still deliver proper fuel levels based on the fact it is no longer limited by the MAF's 255 limit and is able to properly meter.

I have a stupid question about the Extender vs. Extender Extreme. The Extender measures up to 512 gps so we know that the scan tool is showing half of the actual air flow. When using the Extreme does the scan tool show 1/3? I bought an Extreme used but haven't goofed around with it much.

Jim

 

[TurboBob]

I have a stupid question about the Extender vs. Extender Extreme. The Extender measures up to 512 gps so we know that the scan tool is showing half of the actual air flow. When using the Extreme does the scan tool show 1/3? I bought an Extreme used but haven't goofed around with it much.

Jim

yes, extreme, pro, and extreme-G all read 1/3 actual airflow on a scantool.

Bob

 

[turbojimmy]

yes, extreme, pro, and extreme-G all read 1/3 actual airflow on a scantool.

Bob

Good to know - thanks!

Jim

 

[TurboBob]

Something to note.

The PowerLogger will display airflow with the proper scaling. And if you have the Scanmaster upgrade reading data from the PowerLogger, it will be properly scaled as well.

Bob

 

[Dean]

Bob, ya got anything to add for me?

Dean

 

[TurboBob]

yes, but its a long explanation.

I'm buried right now. Let me write it up off line and post tomorrow.

B

 

[Dean]

10-4. Thanks.

 

[Dean]

Geez, someone thinks this is a terrible thread? (One star)

I wonder who and why?

 

[Ed Valvo]

I'd like to know when an Extreme is more beneficial than the regular Extender chip. And are there any downsides to the Extreme?

 

[TurboDave]

I'd like to know when an Extreme is more beneficial than the regular Extender chip. And are there any downsides to the Extreme?

It allows for higher airflow measurements beyond the Extender.

Extender; 512gps Extreme 750something gps. When you start making "extreme" horsepower, you need an Extreme chip.
I think by the time you start look at crossing the threshold from 11's into 10's that's the time to look into the Extreme.

 

[Ed Valvo]

Thanks Dave. I didn't know if there were any other differences or options that come with the Extreme. I really like my Extender chip. I have't changed my fuel pressure in 6 years! I just click it up or down in the translator box as required.