Attempting to adjust biss with ecmlink

[tay97gst]

Well like the title says I'm trying to properly adjust my biss using ECMlink but I'm having a problem I couldn't find with searching. When I start my car and let it idle until normal operating temp, ISCposition will slowly drop down to zero, and no adjustments made to the biss screw will change it's reading. While doing this I did not ground the diagnostics pin because I've read that you should and shouldn't so I'm not sure which is right. It may also help to know that I have replaced the oring in the biss, checked the isc using a voltmeter (was 29-30 for all), and am simulating idle switch in link. Not sure what's going on here. Could it be a bad ISC even though the resistance checked out? I have a spare one I could throw in. I have the ability to post a log showing it drop if need be. Let me know if you have any opinions on what's going on

 

[gusu]

Well like the title says I'm trying to properly adjust my biss using ECMlink but I'm having a problem I couldn't find with searching. When I start my car and let it idle until normal operating temp, ISCposition will slowly drop down to zero, and no adjustments made to the biss screw will change it's reading. While doing this I did not ground the diagnostics pin because I've read that you should and shouldn't so I'm not sure which is right. It may also help to know that I have replaced the oring in the biss, checked the isc using a voltmeter (was 29-30 for all), and am simulating idle switch in link. Not sure what's going on here. Could it be a bad ISC even though the resistance checked out? I have a spare one I could throw in. I have the ability to post a log showing it drop if need be. Let me know if you have any opinions on what's going on

Are you sure there isn't a issue with the ECU?

 

[iaintmaci]

When you adjust the BISS, you need to ground out the connections using ECMLink. Otherwise, every adjustment you make is throwing the ISC farther out of adjustment. When you ground the connections, it sets the ISC to its "neutral position." You can then use the Biss to get everything adjusted properly.

Search youtube. Jafro has a good video on how to adjust your BISS.

 

[josh408]

You might have to play with the MAFComp sliders a bit. When you replaced the o-ring in the biss it probably wasn't set in the same exact spot as when you took it out (which would explain this thread) but try playing with the maf comp sliders and see how that goes

 

[tay97gst]

When you adjust the BISS, you need to ground out the connections using ECMLink. Otherwise, every adjustment you make is throwing the ISC farther out of adjustment. When you ground the connections, it sets the ISC to its "neutral position." You can then use the Biss to get everything adjusted properly.

Search youtube. Jafro has a good video on how to adjust your BISS.

Ive seen jafros video, i must have missed the part where he said to ground it. I will try that next time I try to set the biss, but it still seems odd that it would drop like that since i started the the biss 2 turns out from fully closed like the suggested placement.

 

[black97spyder]

When you adjust the BISS, you need to ground out the connections using ECMLink. Otherwise, every adjustment you make is throwing the ISC farther out of adjustment. When you ground the connections, it sets the ISC to its "neutral position." You can then use the Biss to get everything adjusted properly.

Search youtube. Jafro has a good video on how to adjust your BISS.

How do you ground the ISC connection with ecmlink?

I am needing to adjust my BISS as well, as my idle will go up to 1500-2000 rpm from the set 900 rpm value in ecmlink. It happens when I start the car after its warm or try to put the car in neutral (automatic). The idle switch has been verified to be working properly with link. I know the ISC & biss will need adjusted as I just rebuilt the T/B with STM's milspec T/B shaft seals, replaced the BISS O-ring, and did the free FIAV block off mod.

thanks!

 

[iaintmaci]

In ECMLink, you need to ground the timing and diagnostic pins. It is under the Misc tab. This will lock the base timing and ISC motor into place. That way there are no variables to change you idle. This gives you a base to set your idle off of, that way when your ecu is shooting for idle, it isn't attempting to set it to the wrong values. When adjusting the BISS, if you have no boost leaks and a good O-ring, a small turn can change the idle a great deal. I would turn the screw 1/4 to 1/2 of a turn, and let it sit for a few minutes to adjust itself. Take your time and let the idle settle after making adjustments. While your at it, I would double check your base timing since you are already going to have your connectors grounded.

 

[black97spyder]

Okay awesome! Thanks!! I will do that after I get done replacing my valve stem seals this weekend!

 

[My1GLaser]

I am only replying to get some clarification of the procedure for myself, since I have never grounded the diagnostic terminal while using link to adjust my BISS.

I watched the video and at the end he says to ground the diagnostic terminal when adjusting the BISS. But it doesn't say that you need to do that when using DSMLink. It just says to shoot for 32 ISC position, which is what I always do. Should I be grounding it first?

 

[steve]

If your setting the BISS by selecting the two boxes in DSMLink or by grounding the physical connectors (mainly 1G) your causing the ECU to step the ISC to the default position and then adjusting the BISS so that the car idles at the programmed idle speed.

If you not selecting the two boxes in DSMLink or by grounding the physical connectors the ECU is using the ISC to control the idle and your adjusting the BISS to get the ECU to step it to about 30 while idling at the programmed speed.

In the first case the ISC doesn't move until after the adjustment, in the second it moves during the adjustments.

 

[tay97gst]

If your setting the BISS by selecting the two boxes in DSMLink or by grounding the physical connectors (mainly 1G) your causing the ECU to step the ISC to the default position and then adjusting the BISS so that the car idles at the programmed idle speed.

If you not selecting the two boxes in DSMLink or by grounding the physical connectors the ECU is using the ISC to control the idle and your adjusting the BISS to get the ECU to step it to about 30 while idling at the programmed speed.

In the first case the ISC doesn't move until after the adjustment, in the second it moves during the adjustments.

So in my case where iscposition constantly drops even when changing the biss without being grounded, why do you think it could be happening?

 

[steve]

So in my case where iscposition constantly drops even when changing the biss without being grounded, why do you think it could be happening?

ISC is bad or some of the ECU ISC drivers are blown. The ECU keeps trying to step the ISC to slow down the idle speed and since the ISC isn't really moving the step count inside the ECU goes to 0.

 

[tay97gst]

ISC is bad or some of the ECU ISC drivers are blown. The ECU keeps trying to step the ISC to slow down the idle speed and since the ISC isn't really moving the step count inside the ECU goes to 0.

Ok i'll swap out the isc next chance i get and will report back, thanks pal

 

[steve]

If any of the ISC coils were ever shorted the matching ECU ISC driver is blown and the ECU circuit board traces potentially damaged.

I received many ECU's where the driver didn't look blown but it wouldn't pull enough current to make the ISC step correctly.

 

[tay97gst]

Well I swapped out the ISC with another one I had and it still does the same thing, lrnidleadjust is stuck at 144 and ISCposition just drops as it warms up. Im gonna post the log just so you guys can see what I'm talking about. So I guess this means the drivers are bad. What would be the consequences of not having the ecu fixed? Just a non working ISC and screwy idle?

 

[tay97gst]

Bringing this thread back in hopes of pinpointing what it could actually be. I sent off the ECU to ecmtuning to be checked out and they said all the ISC drivers were perfect, and that the ISC worked perfectly when attached to his car so it's definitely something on my end. I'm pretty sure it's not a boost leak because I've tested multiple times and fixed all the ones around the IM/TB. Could it be that I don't have a ground on my TB(6bolt)?

 

[phr0st]

Bringing this thread back in hopes of pinpointing what it could actually be. I sent off the ECU to ecmtuning to be checked out and they said all the ISC drivers were perfect, and that the ISC worked perfectly when attached to his car so it's definitely something on my end. I'm pretty sure it's not a boost leak because I've tested multiple times and fixed all the ones around the IM/TB. Could it be that I don't have a ground on my TB(6bolt)?

The ground would really only matter for sensors that ground through the body (IE Idle switch) but it's still a good idea to have a ground. Make sure that your throttle cable is adjusted properly and not holding the throttle plate open a tad. Sounds to me like you have air getting past the tb. People with link often have the throttle cable too tight and try to compensate for the screwed up tps range with links TPS adjust tool.

 

[tay97gst]

The ground would really only matter for sensors that ground through the body (IE Idle switch) but it's still a good idea to have a ground. Make sure that your throttle cable is adjusted properly and not holding the throttle plate open a tad. Sounds to me like you have air getting past the tb. People with link often have the throttle cable too tight and try to compensate for the screwed up tps range with links TPS adjust tool.

Alright i'll look into the throttle cable. Could it also be that the idle stop switch is screwed in too far causing the plate to be open a little as well?

 

[phr0st]

Alright i'll look into the throttle cable. Could it also be that the idle stop switch is screwed in too far causing the plate to be open a little as well?

Yes very much so. This is quoted from another thread:
"To adjust the switch. You unloosen the lock nut of the switch, turn it all the way out counterclockwise. Make sure you loosen up the throttle cable as well. Get you meter put on a good ground and the positive on the switch, turn switch in until you get continuity, when it is constant;turn the switch 15/16 of a turn clockwise, stop and tighten up the lock nut and your done. Make sure you tighten your throttle cable." Obviously if the switch doesn't work you may have issues seeing it connect to ground but basically you can screw the switch in until the button is depressed but it doesn't move the idle plate then 15/16 of a turn CW and lock it. Also put some fingernail polish or something on it once you have it set so you know you can line it back up later if need be.

*Edit it is important to note that if the cable is too tight and holding the plate open when you set the idle switch it WILL be wrong. For setting the idle switch I also remove the cable from the TB so I know it won't interfere.

After you set the idle switch to the correct location you can open the throttle plate all the way and then let it snap shut. Then start the car and check you ISC position. Sometimes the clunky cruise control mechanism can also hold the plate open a bit.. if it actually idles correctly after letting it snap shut then it's either the cable too tight of the cruise control sticking.

 

[tay97gst]

Yes very much so. This is quoted from another thread:
"To adjust the switch. You unloosen the lock nut of the switch, turn it all the way out counterclockwise. Make sure you loosen up the throttle cable as well. Get you meter put on a good ground and the positive on the switch, turn switch in until you get continuity, when it is constant;turn the switch 15/16 of a turn clockwise, stop and tighten up the lock nut and your done. Make sure you tighten your throttle cable." Obviously if the switch doesn't work you may have issues seeing it connect to ground but basically you can screw the switch in until the button is depressed but it doesn't move the idle plate then 15/16 of a turn CW and lock it. Also put some fingernail polish or something on it once you have it set so you know you can line it back up later if need be.

*Edit it is important to note that if the cable is too tight and holding the plate open when you set the idle switch it WILL be wrong. For setting the idle switch I also remove the cable from the TB so I know it won't interfere.

After you set the idle switch to the correct location you can open the throttle plate all the way and then let it snap shut. Then start the car and check you ISC position. Sometimes the clunky cruise control mechanism can also hold the plate open a bit.. if it actually idles correctly after letting it snap shut then it's either the cable too tight of the cruise control sticking.

Well I swapped out the 1g tps to a 2g tps in order to eliminate the idle switch portion completely, and then adjusted the throttle cable again. Seems to have done the trick! Now ISCposition is reading instead of dropping to zero. Wish I had thought to do this before I sent out my ECU but oh well, at least the issue seems to be fixed. Thanks guys