Grounding ECU

Does anyone know how to do that? I need to ground my computer in my car...

i haven't looked at the ECU, but i'm sure once you plug it in, you somehow secure it to the car/firewall/floor via bolts. this should take care of the grounding. the ECU doesn't just float around plugged in behind center console....does it?

Hehe Yeah, I know it's grounded right now but it's for something else. I mean, I was told that to properly adjust the idle, you have to have the ECU grounded before you turn the BISS. This is because when the ECU is actively on, it's controlling other stuff as well (or something like that). At any rate, supposedly if I ground the ECU then I could properly tune the idle via the BISS and from there when the ECU kicks back in, itt'll properly adjust other stuff.

Do you mean which pin is hte ground on the ECU, because as linebckr said it is already grounded via the frame and also through the harness.

Sounds like you are putting it in diagnostic mode, such as below for pulling codes:

http://www.stealth316.com/2-diagconn.htm

All ecu year and model ECU pins:

http://www.stealth316.com/2-ecu-terminals.htm

However, I've never heard that it was necessary to do that, generally I was always under hte impression that you could just turn the BISS screw while the car was on just like normal, no extra grounding necessary. Who told you that you had to ground it additionally?

Jason at dsmisc.com told me about the additional grounding. It actually makes sense because when I was turning my BISS with the ECU still fully functional, the idle barely moved because the ECU was probably still trying to control the idle. But supposedly when you have the ECU grounded and it is not interfering with the idle anymore, then the idle will go up and down smoothly.

I found this online: http://www.ecanfix.com/users/manualcd/gift/3s/3s_fuel.pdf (page 65 to 66)
But I don’t really get it so maybe someone can explain some stuff to me...hopefully...

Is it possible to make the special tool? I can’t really see what it’s made of so maybe someone here could tell or have done it before!?!

Also, I have a digital multi-meter....will that be able to replace the voltage tachometer? The one in the picture looks like an analog one though….don’t know if it makes a difference or not. The thing is though is that the multimeter doesn't have a crocodile teeth grip...are those made as well?

Finally, I see where the paper clip is supposed to go but it isn't really clear as to how we're supposed to put it in. Do I clip it or bend it and stick it somewhere?

Okay, thanks guy…

Jason at dsmisc.com told me about the additional grounding. It actually makes sense because when I was turning my BISS with the ECU still fully functional, the idle barely moved because the ECU was probably still trying to control the idle. But supposedly when you have the ECU grounded and it is not interfering with the idle anymore, then the idle will go up and down smoothly.

I found this online: http://www.ecanfix.com/users/manualcd/gift/3s/3s_fuel.pdf (page 65 to 66)
But I don’t really get it so maybe someone can explain some stuff to me...hopefully...

Is it possible to make the special tool? I can’t really see what it’s made of so maybe someone here could tell or have done it before!?!

Also, I have a digital multi-meter....will that be able to replace the voltage tachometer? The one in the picture looks like an analog one though….don’t know if it makes a difference or not. The thing is though is that the multimeter doesn't have a crocodile teeth grip...are those made as well?

Finally, I see where the paper clip is supposed to go but it isn't really clear as to how we're supposed to put it in. Do I clip it or bend it and stick it somewhere?

Okay, thanks guy…

kind of funny because i was having the same problem a week ago... i adjusted the biss a little and that took care of my idleing at stoplights problem i also had a digital meter and not analog like you but couldnt figure it out so i tried the paperclip thing but wasnt getting results so i said fuck it and gave up

How much were you turning the BISS screw when you said it didn't work. Because it might take a couple full turns. Also, the rubber o-ring can get hard over time and make it harder to turn it, or basically choke it back down, so you should replace that.

I really cannot ever remeber reading anything about anyone needing to ground or mess with the ECU to do this though. I'm not familiar with Jason or the other website, but being that it has DSM in the title, could it be possible that is a DSM trick, I mean our ECUs are drastically different from theirs.

Well, if you click on the link on top that I posted, the procedure is actually out of a 3000GT service manual. So yeah, I think to properly set the idle correctly on cars, you do have to somehow ground the ECU or something so that it's not interfering with during the adjustment.

However, from what's happened with my car recently, this is what I think takes place... Again, in theory to set the idle correctly, one would have to ground the ecu. So does that mean that if the ecu was not grounded when adjusting the BISS then your idle would just be super off? No. The reason is that your ECU would ultimately determine where the idle should be at if your IAC is working properly (learned that from Stealthee - hehe :)). Therefore, if your idle is too high or too low, the ecu will adjust it for you. But if you're like me who would like everything "perfect," then you go through the extra work and try to get things lined up...

...only to spend the whole day trying but never getting it done. LOL

I bought wires and those aligator clips to ground my ecu following the procedure that was located in the link but it didn't work. When I started my car, it kept dying with everything connected. I finally gassed it a little during start up and my car stayed on but the idle was super low with the CEL on. I turned the BISS a bit but nothing really moved so I didn't want to get it super out of alignment so I just stopped. I set turned the BISS back to where it was before, unhooked everything, and just started her up again.

So where does that leave me? I guess in the end the IAC probably was broken seeing that my car did eventually hold idle after my IAC was installed. I still think my idle adjustment is off but seeing that the ecu can compensate for it right now, I'll just leave it alone. If anyone knows how to actually ground the ECU properly to adjust the idle then I'll be more than willing to try again. But if not then it's running fine so I'll just leave it the way it is for now.

Thanks again to everyone who helpped on this problem. I had lots of questions and appreciate the patience that you guys gave me. :)

sportsb4life7, I'm very interested in how you approached the paper clip deal as some parts were a bit fuzzy to me....so if you don't mind, please let me know. Thanks again.

Slade you were right, I got it for you. Did a search you know where, and got this:

"Before adjusting the screw- ground the timing connector at the passenger side shock tower/firewall area."

http://www.stealth316.com/2-checkconns.htm

Oh wait, the only thing that needs to be grounded is the timing connector (the brown piece)? Why does the manual make you do all those other steps then...hmm....interesting.... Maybe I'll try just grounding ignition timing when I get home...doing that shouldn't mess anything up right? Hehe

Well i got these instructions off 3si

Simple to check engine codes though. Take a thin paper clip, and undo all the bends. When it's straight, form a "U" shape (you could also use a wire). Look underneath the dash behind the steering wheel and you'll find a little white box with a bunch of ports. Each port has a number. With the car off, you want to *GENTLY* push each end of the paperclip or wire into the 1 and 4 numbered ports. Then turn the key into the on position (don't start car). The check engine light will flash twice, then pause, and then start flashing again (you want to start counting here). Long flashes first, pause, then quick flashes. Count each time it flashes respectively. Like, 5 long flashes and 3 quick flashes would be code 53.
Here's the codes:

11 Oxygen Sensor (rear if Turbo) yes Harness, Ox sensor, Fuel pressure, Injectors, Intake air leak
12 Air flow sensor yes Harness & connector, Replace Air flow sensor
13 Intake air temp. sensor yes Harness & connector, Replace Intake air temp sensor
14 Throttle position sensor yes Harness & connector, Replace sensor, Idle position switch
21 Coolant temp. sensor yes Harness & connector, Replace Coolant temp. sensor
22 Crank angle sensor yes Harness & connector, Replace Crank angle sensor
23 Top dead center sensor yes Harness & connector, Replace Crank angle sensor
24 Vehicle speed sensor (reed swch) yes Harness & connector, Replace speed sensor (reed switch)
25 Barometric pressure sensor yes Harness & connector, Replace Barometric pressure sensor
31 Detonation sensor (DOHC) yes Harness & connector, Replace Detonation sensor
36 Ignition timing adjustment signal no Harness & connector, normal when setting timing
39 Oxygen Sensor (front, turbo ) yes Harness, Ox sensor, Fuel pressure, Injectors, Intake air leak
41 Injector yes Harness & connector, Check injector coil resistance
43 EGR (California) yes EGR temp. sensor, EGR valve, EGR control solenoid, EGR valve control vacuum
44 Ignition coil, transistor #1-4 yes Harness & connector, Ignition coil, Power transistor unit
52 Ignition coil, transistor #2-5 yes Harness & connector, Ignition coil, Power transistor unit
53 Ignition coil, transistor #3-6 yes Harness & connector, Ignition coil, Power transistor unit
61 Transaxle control signal (A/T) yes Harness & connector, Replace Transaxle control unit
62 Induction control position sensor (DOHC, non turbo only) yes Harness & connector, Induction control valve

but the thing is i tried this and it wasnt working.... ive heard to use the 1 and 4 ports but also like 1 and 12 ? and im not sure i also dont think i was puting the paper clip on the right spot there were like holes below the numbers but also like metal little pieces and i couldnt hold the paperclip steady enough and then look up at the check engine light - has anyone here actually done it?

Hmm...well it sounded like you were trying to pulle codes whereas I was trying to do something different. This is what I did:

1-stuck a paper clip in the blue pin
2-clamped a jumper wire the paper clip and the other end was connected to the red pin of my digital multi-meter. The black pin was grounded and the multi-meter set to 20 DC volts.
3-stuck a paper clip in terminal 1 of the ecu and clamped a jumper wire on the clip and the other end was grounded.
4-grounded the ignition timing.

But again when I started the car I was having issues so it kinda never worked. The step that I'm really unsure about was step 2 because I'm not sure if I grounded the multi-meter was supposed to be grounded or not but I just did it. Also, not too sure if I needed an analog volt-meter so....

Well, if anyone knows how to properly do it then I'm all ears. :)

just ground that brown piece to the chassis, and then connect pin 10 to pin 12 with a paperclip or whatever. Then go for it. That's how I interpretted it.

^^Wait, are we talking about pulling codes or grounding the ECU? You wouldn't happen to still have the link that you read it from do ya? Thanks Vert.

I'm talking about grounding the timing connector which puts the ECU into idle adjustment mode, so you can set hte idle. Do exactly like I posted in the last 2.

That is pretty much all the post I found on it said. The stealth316 links are showing where the timing connector and pins are. Forget anything about pulling codes.