VikingTrad3r

it appears that for the 85, there is NO WAY to datalog in "normal" mode?

iow, we can datalog but its going to be in 10k mode where parameters are adjusted, no way to view normal operation b

is this true? why would gm make a car where the "normal operations" of the car cannot be observed in operation.

am i missing something?


example: I would like to set my minimum Idol using IAC counts. however I cannot do this because the 85 will not let me "look "at the I a C values during normal operation. I can only look at the values while in 10K mode which puts the RPM of the vehicle to 1000rpm, among other things, to different values. so i cannot use the iac count technique of minimum idle setting on an 85. nor can i see any other variable at idle because it wont let me collect data at anything other than a ecm induced 1000rpm fervour.


am I missing something?

ive seen loads of threads with details on how to kick the 86 and later datalogging sessions out of the high idle once the feed is established. none for the 85.

anybody holding a magic key of knowledge for this?

Cliff Harris

The basic problem with the '85 ECM is that it operates at 160 baud. Each piece of data has 10 bits, so that's 16 parameters per second. The data stream is 25 bytes long, so it takes about 1-1/2 seconds to get a complete set of data. That's way too slow to get meaningful information out of the ECM. That's why people switch to the 1227165 ECM, which can output data at 8192 baud.

You also need to look at the data stream that comes out of the ECM. Many parameters are not transmitted. The IAC count IS transmitted, so at least you have that.

VikingTrad3r

thanks for that Cliff. i do find it useful and i do see almost everything i need,albeit slow, but i csn get a good datalog session.

the problem i havnt solved yet is that i cannot find a way to stop the 1000rpm situation with the 85. i cant "observe" what is happening at idle in the 85 because the only way it transmits data is with the 10k on ab and that puts it into aldl mode with 1000rpm and other changes.

so if i want to know what my iac iac is at idle, to set min idle, i cant do it.

Cliff Harris

How do you get into 10K mode? Is there a 10K resistor inside your cable? Many cables have a 10K/open switch. I assume yours does not.

Maybe you just need a more versatile cable.

VikingTrad3r

the cable i have is from http://www.aldlcable.com

its the 12 pin with the jumper on the usb end. the jumper in different configurations allows different communications modes to the ecu b

i have no idea how to get into normal mode.

Cliff Harris

Is there documentation on this cable?

I think the jumper is the key here. Try it with and without the jumper and see what happens (the empirical approach).