Hey all,


I bought the serial version of the aldl cable from www.aldlcable.com. I have an 88 gta which requires the 10k resistor to be enabled to begin data flow. this works, but when the cable is connected, my engine rpm won't drop below 1000rpm??? cable unhooked, all systems go. cable attached, idle rpm jumps up (even if not attached to the laptop). any idea wtf thats about? I have done a search, but have seen nobody else with this issue.


thanks everyone,

Jason

 

I have the usb cable and get the same thing.It will be interesting to find out what poeple say about it.

 

yeah.. if the cable is skewing the data and causing rpm issues, how can we be sure we are recording a clean run? i don't want to be programming a chip on flawed data

 

Im not familiar with the cables you guys are using. But check if your cable has a switch or some other way of disconnecting the 10 k resister, that should allow you to datalog without the strange issues.

 

You can pull the 10k resister out.If it is out it doesnt read.thunder85 is yours the same way?

 

yes, its the same; mine won't read without the 10k resistor. It will also read when the cable is jumpered into diagnostic mode.

 

What happens if you leave the resistor connected until you establish communication between your laptop and ecm then remove it after your connected ?

 

damn. i hadn't thought to try that. i got my intake off right now.. can one of u other guys with the problem try it and see?


884+3... you have an 88 as well, what aldl cable are you using? any issues?

 

Im using one of Craig Moates' APU1's so i can't really help you out with the testing of my ideas. Also im using a 730 ecm.

 

ah... gotcha. i am still using my stock ecm.. i just got a burn1 and adapters from him to start generating some chips. thats my concern... i am going to start logging data so i can better tune my ride, and the skewed rpm thing is just weird. and seeing that i am not the only one makes me feel better (i'm not completely nuts)

 

In aldl mode the chip (gm oem) adds 10 degress of spark timing. Sends rpm up and gives you extra spark retard at load (wot).

It is a real pain.

To remove (set to zero) a new chip has to be burned.

 

If memory serves me, with my OTC scaaner there is more than one diagnostic mode available. I think there are at least ROAD and ALDL modes, maybe another. I think the ALDL mode might be causing your symptoms and is perfectly normal. You are not supposed to drive in ALDL mode as far as I remember, only in ROAD. Of course I've slept since then, I may have dreamed all of that.

 

well i have just got done modifying an arap bin with the basics (highway mode, fan temps, quicker startup, etc). what flag or table do i change to lose that lovely 10degree spark jump during aldl mode?

also, my cable doesn't have more than the 3 modes... no resistor, 10k resistor, and diagnostic (a+b jumpered). at least per the instructions. i have emailed the manufacturer about this as well... if they bother to answer me i will let u guys know.

 

This is for $32
In the BUA Hack it is on page 3


LC022: FDB 57 ; Fixed S.A. For Diag, (20 Deg)

LC024: FCB 23 ; 8 Deg Add S.A. for ALDL Hex 17

For $32b & $6E
It is at LC023: FCB 23 ; HEX 17 ; 8 Deg Add S.A. for ALDL

Sorry that it is only 8 Deg not 10 deg.

 

i just found this guys...it appears not to be just a spark issue, but the aldl mode also alters the iac parameters for some reason.



FYI...from AllData database for 1988 IROCZ
ALDL Mode Description
The SCAN tool can be used in 3 different modes:

1. The normal or open mode
2. The 10K, special or ALDL mode
3. The factory test, back-up or 3.9K mode

Most SCAN tools are programmed so that the system will enter the special (ALDL, 10K) mode directly, and the `normal' or `factory test' modes must be selected manually, if available.
In the special mode, all information incorporated into an engine/ECM combination is available. However, in the special mode engine operating characteristics are modified as follows:

* The closed loop timers are bypassed
* EST spark is at full advance
* The IAC (if equipped) controls idle speed at 1000 RPM
* The park/neutral restrict functions are disabled
* And on some engines the canister purge solenoid is activated.


...the remaining terminals of the ALDL connector allow access to specific system circuit information. Terminals ``E'' or ``M,'' depending upon the application, allow for the connection of SCAN type testers in order to read serial data.

Although not all engine/ECM `families' are able to transmit information on the serial data line with the SCAN tool in the normal (open) mode, on engines that can be monitored in the open mode the SCAN tool allows data on certain operating parameters to be obtained without changing engine operating characteristics. Selecting the factory test or back-up mode causes the ECM to operate on the fuel back up logic programming, designed to allow system operation in the event of an ECM failure. While selection of this mode verifies that the back up programming is functioning properly, parameters that can be checked with the tool in this mode are of little value in diagnosing system malfunctions.

 

None of this is new. Just remove the 10K AFTER you connect, that is all there is to it.

You can zero out the ALDL spark adder, but there are other items that are also affected. Such as the forced high idle speed.

Just remove the 10K after the ALDL connects.

RBob.

 

sorry rbob, i had done several searches with no luck or info. thanks for the proper aldl use info... that makes my life much easier. i didn't realize that the 10k was only to trigger the data flow, and that it continued once the 10k was removed. that is not in the instructions that came with the cable either, and emailing the company only gave me the info i just copied into my post.

I am a newbie at data acquisition and eeprom modification, so i guess prone to dumb questions. if there were a sticky or something for new people regarding data logging/interpretation and aldl cable use it would probably reduce the dumb questions.

 

Hello,
I'm new and i'm from Italy. I've a 86 iroc-z with 205 tpi vin F. Yesterday i start a Scan and it works only in special mode (idle 1000rpm etc.). I disconnect the Scan but Now when i run the car seems that it work like in special mode. it's strange. How can i set my car in normal mode?
Thanks.
Fausto