I believe most on here know there is more than one mode that the stock V6 Fiero ECM can be placed in.

One I will call 'diagnostic mode' - This is accomplished by shorting pins A - B. In diagnostic mode, WITH THE ENGINE RUNNING, timing advance is disabled. Also the SES light flashes to indicate if the current mixture is rich or lean.

Also in diagnostic mode, WHEN THE ENGINE IS OFF, the ECM fully extends (closes) the IAC motor, and flashes the SES codes.
----

The second mode I will call 'ALDL mode". This is accomplished by placing a 10K resistor between pins A-B. When the ECM is in ALDL mode, the ECM will output data via the ALDL connector.

---

I question does the ALDL mode eliminate the timing advance. Since you can see the timing advance in the ALDL stream, it surly doesn't make sense that the timing advance is inhibited. I haven't confirmed this, but my 'thought experiment' says it should work this way. I am not running a stock 1227170 right now, but I can set one up on my test ECM engine simulator and see what I get for an output.

--

Also are there other changes that happen when the ECM is in ALDL mode?
---

If you have input, but if it's about the duke ECM, please make that clear in your post. I would think both operate the same, but who knows?

I know on the V6 (85 tune) I have watched the advance with a timing light while logging and timing is in affect in that mode.
I also notice some differences while in ALDL mode but not sure what is going on. Idle seem to be affected some and idle hunting issue acts different sometimes.

[This message has been edited by Dodgerunner (edited 01-11-2013).]

Watching this one...I've noticed as well that the engine runs a little bit differently in ALDL mode.

in some bin's the egr was opened while in ALDL mode and a certain amount of timing was added. if you have a fully disassembled bin there may be a couple of scalers to confirm. HTH

------------------
'97 Ram SS/T
'87 Mustang GT- 7730 w/S_AUJP V4
'86 Fiero SE- 7730 swap in progress
'85 S10 Blazer- ARI 3.4; GT3582R

watching this one.

Want to do a bluetooth ALDL connector so I can run a similar app to Torque on Android (just for ODB1) and monitor parameters realtime. Or replace gauges with an Android tablet.

quote Originally posted by 34blazer660: in some bin's the egr was opened while in ALDL mode and a certain amount of timing was added. if you have a fully disassembled bin there may be a couple of scalers to confirm. HTH

That makes sense

quote Originally posted by Austrian Import: watching this one. Want to do a bluetooth ALDL connector so I can run a similar app to Torque on Android (just for ODB1) and monitor parameters realtime. Or replace gauges with an Android tablet.

I do sell one - http://www.reddevilriver.com/ALDL_Bluetooth.php

You Scan tool/software read idle speed ~1000?
Normal operation. Any scanner on DIS L4 will get same result.

1. Most/all OBD1 ECM isn't made for "multitask operation."

2. When streaming data... ECM trying to run the engine AND streaming data is a multitask mode and ECM can/will bump idle speed...

Read ECM or idle speed in SM...
I forget exactly where...
Normal Idle = ~900 RPM
Idle speed when scanning data = ~1000 RPM


------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

[This message has been edited by theogre (edited 01-11-2013).]

quote Originally posted by phonedawgz: I question does the ALDL mode eliminate the timing advance. Since you can see the timing advance in the ALDL stream, it surly doesn't make sense that the timing advance is inhibited. ... Also are there other changes that happen when the ECM is in ALDL mode?

Both theoretically and based on personal test experience, I would confidently say that ALDL mode does not turn off timing advance.

From this link, in ALDL mode (Fiero v6):

• "Timers" are "expired."
  
• IAC is reset the first time RPM > 2000
  
• Integrator reset criteria are disabled
  
• Bypass RPM and Temperature criteria for ESC enable
  
• Set idle to 1000 RPM

From this link, the Fiero 4-cylinder ECM does the same, but adds:

• Bypasses Lean clamp for integrator

The data referenced above is attributed, in this link, to "Dr. Bradley Warren Smith, General Motors Corporation, Southfield, Michigan."


As another source, Oliver Scholz (fieroluke here on PFF), who probably knows as much as anyone on the planet outside GM about the ALDL mode in Fiero ECMs, comments somewhat cryptically in this link:

"[10K mode] puts the engine in diagnostic mode, in which it doesn´t behave normally, e.g. some P/N restricted functions are enabled and some closed loop timers are bypassed."

I have had Oliver's DashScan II installed in my Formula (3.1 V6, 7170 ECM) for many years, and I have driven it around in "Scantool Mode" (I.e. ALDL Mode or 10K Mode) for more than half an hour at a time while data logging without any noticeable irregularities in engine operation. I still wouldn't advise regularly driving around in ALDL mode, though.

[This message has been edited by Marvin McInnis (edited 01-14-2013).]

quote Originally posted by masospaghetti: Watching this one...I've noticed as well that the engine runs a little bit differently in ALDL mode.

I have heard (and maybe perceived) this, as well.
One of my friends noticed a drastic difference with his V6, in ALDL mode. This was a V6 swap into a 4 cylinder car, so I can't say which ECM it was.

Thanks for the in depth input

It would be interesting to see the parameters before putting the ECM in ALDL mode, but the act of scanning them changes them.

Quantum Fieros?

[This message has been edited by phonedawgz (edited 01-12-2013).]

quote Originally posted by Austrian Import: Want to do a bluetooth ALDL connector so I can run a similar app to Torque on Android (just for ODB1) and monitor parameters realtime. Or replace gauges with an Android tablet.

Most OBD1 and some OBD2 Won't like scanning full time like you and many think. Bluetooth etc doesn't matter. Just connect 10K resistor will force ECM into "Scantool Mode."

GM OBD1 data isn't a real time output. Example: The Tach direct connected to HEI/DIS is much faster to read RPM than ECM streaming data.

By the time any scan tool shows ECM data... Scan data is old data. 1-2 seconds old that can matter.

Think this way... In Scan tool mode, ECM takes a snapshot then output that snapshot 1 or 2 times a second. All using "Stolen" CPU time to generate the streaming data. I used "Stolen" because streaming data is not ECM's primary function. IOW... Streaming data takes CPU time away from running the engine. C3 and P4 ECM uses slowest/cheapest CPU and is made just to run the engine. Running streaming data then running engine does suffer.

ECM CPU is not PC CPU etc... ECM only sees and use 1 "Thread."

"Quantum Fieros?"
Funny.
Most all GM OBD1 has same issue. Most users don't have a clue that ECM will change when in scan mode vs normal run the engine.

The stock Fiero ECM sends the parameter updates about once a second.

One of my bench 'mule' ECMs is a 16132240 4.9 ECM. I would expect the other 8192 pin M ECMs to be about the same speed. Testing using my bluetooth adapter, I establish the bluetooth connection, and then to assure myself that I am indeed getting data, instead of seeing a frozen screen, I wet my finger and then tap it on the pins of one of the other open connectors. (All of the power, and ALDL data happen to be available on one of the three ECM connectors). Tapping in the right place moves around a 'constellation' of parameters. Anyways, even with the bluetooth connection in place, almost as fast as I can tap is also as fast as the parameters are updating in TunerPro RT. I can tap multiple times a second and the screen keeps right up with my finger. When I pull my finger from the connector, I sometimes see a single flash of a number before the reading goes back to zero. Perhaps this response time is about 100 mSec.

I would equate the response to be slightly faster than what you can expect from a mechanical analog gauge.

I'll try this on a Fiero ECM later and let you know the timing factor my 'calibrated' eye comes up with.

quote Originally posted by phonedawgz: The stock Fiero ECM sends the parameter updates about once a second. One of my bench 'mule' ECMs is a 16132240 4.9 ECM. ... Tapping in the right place moves around a 'constellation' of parameters. Anyways, even with the bluetooth connection in place, almost as fast as I can tap is also as fast as the parameters are updating in TunerPro RT. I can tap multiple times a second and the screen keeps right up with my finger. When I pull my finger from the connector, I sometimes see a single flash of a number before the reading goes back to zero. Perhaps this response time is about 100 mSec. I would equate the response to be slightly faster than what you can expect from a mechanical analog gauge.

Maybe true but if you read MM links... Scanning still changes engine setup to free up and/or fix lost CPU time to stream data etc. Running ~1000 RPM idle is not good in most setups. GM made this feature, ALDL/10k Mode, as temporary use only.

Running Auto trans w/ higher idle can heat TC and trans, can affect braking too. Higher idle then higher torque to wheels means longer stopping distance.
Stick trans won't care as much.

Timing is not fixed in 10k mode, but there are a lot of things in the ECM that change in this mode, as others have pointed out in this thread, which is why GM doesn't recommend driving around in 10k mode other than for diagnostic purposes.

As far as update rate is concerned, the Fiero V6 uses a C3 ECM, which has 160 bits per second, and each diagnostic frame is 25 bytes of 9 bits each, which results in roughly 1.5 seconds between updates. The 84-86 L4 ECM is slightly faster because the frame is shorter. There is nothing you can do to speed up the update rate or get more "realtime" data, unless you add a communication chip and some custom code. I've done that, I have three of those experimental Class2 ECMs with extra RAM and Flash PROM in my basement, but with my 7730 swap those became obsolete. But I digress.

The 7730 as well as the 87/88 Fiero ECM communicate with 8192 bits per second, so even with a frame almost 4 times the size (~66 bytes), the data feels "realtime". It's still old data, but not 1-2 seconds old, but milliseconds old, faster than you can look anyway. Still, when logging data there's still the possibility of missing a glitch if it's short enough, but it's far less likely than with the old data stream.

Hope this helps to clarify some things.

quote Originally posted by fieroluke: The ... 87/88 Fiero ECM communicate with 8192 bits per second ...

Thanks for your comments, Oliver. To clarify ... that's the 87/88 L4 only, isn't it? The 7170 ECM in the 87/88 V6 is still at 160 bps.

[This message has been edited by Marvin McInnis (edited 01-14-2013).]

That's correct. All (stock) Fiero V6's are 160 baud.

The 7730 is fast at 8192 baud, but does not output fuel consumption information :-( Not unless hacked ;-)

quote Originally posted by Marvin McInnis: Thanks for your comments, Oliver. To clarify ... that's the L4 only, isn't it?

just making sure everyone is on same page...

87 & ^ DIS Duke uses 1227748 is P4 Family ECM contains integrated Cruise Control logic, 2 fan control output, MAT sensor input... P4 ECM is one step below PCM that controls trans shifting too.

8192 baud on ALDL E, faster rate but longer data stream.

Is why Scan tool is a must many time.
Only adjustment on DIS L4 is idle stop screw. Every else is ECM and DIS module control.

[This message has been edited by theogre (edited 01-14-2013).]

87 & ^ DIS Duke uses 1227748

8192 data on pin M

[This message has been edited by phonedawgz (edited 01-14-2013).]

quote Originally posted by fieroluke: That's correct. All (stock) Fiero V6's are 160 baud. The 7730 is fast at 8192 baud, but does not output fuel consumption information :-( Not unless hacked ;-)

Im using a modified $8D, S_AUJPV4, has fuel consumption calculated. dont ask about how it was figured out, but works pretty well. it didnt take much to run the factory 2.8L either and still uses the analog EGR.

quote Originally posted by phonedawgz: 87 & ^ DIS Duke uses 1227748 8192 data on pin M

Opp yes M... Tired Ogre...