2g Idle - Verify Correct Operation

[randman2011]

I've never really understood the whole process to set idle on a 7 bolt. I just turn my BISS to raise or lower the idle in my car, but people talk about grounding the timing pin on the ECU. What does that do? Am I supposed to have to do that to set my idle. If so, does that mean that something's broken on my engine? This engine has had three different ECUs and has been hooked up to two different cars, so if there's a problem it must be with the throttle body. I'm also getting idle surge now. Any chance they're related? Should I be concerned>

 

[codym]

http://www.vfaq.com/mods/BISS-2G.html

http://www.dsm.org/how-tos/tttt/tttt3.html

 

[randman2011]

http://www.vfaq.com/mods/BISS-2G.html

http://www.dsm.org/how-tos/tttt/tttt3.html

I have already read both of those and still have both of the windows open. I am not asking how to adjust my idle. I'm asking what is broken if I don't have to follow the correct procedure to adjust it. I already know that I have to rebuild my throttle body, but I need to know if I have to order replacement parts now since I have a 40 minute commute every day and no other means of transportation. I'm assuming this means that there is a problem with my ISC somewhere, whether it's the controller or the coils, but I was hoping someone would have some input on the matter. I'm hoping to check resistances tomorrow after work, but I've been saying that for two months now.

 

[BostonGST]

You can just turn it, I'd have the car off and turn the screw a little. But wait until you get to operating temp to see where the idle is.

I was nervous too about the grounding but after reading tons of ppl talk about turning the screw w/o any mention to grounding I just went for it and it was fine.

 

[randman2011]

I got a chance to get under the hood yesterday. All four coils checked out at exactly 38 ohms, but my multimeter is analog and cheap so I'm not concerned. A lot of me is kind of disappointed that that's not the problem because at least it's easy to fix. I discovered that my turbo is very blown, so that has occupied my time since yesterday. I ordered all new TB gaskets and seals that should be arriving with my new turbo, so maybe it's just a leak that I'll fix when I rebuild the thing.

 

[codym]

Following the correct procedure to set it should be done first before trying to find what's broken. The BISS and ISC may be in perfect working condition, but if they are out of adjustment your going to encounter the same problems.

You asked what grounding the timing and diagnostic plug does, the first link I provided explains the entire process of setting the BISS properly, and why the pins need to be grounded. In a nut shell, If the BISS is not adjusted right, your ISC will compensate and than will also be out of adjustment. If you don't ground the plug behind the battery and the pin on the diagnostic plug, it won't adjust correctly.

"The BISS helps the ECU maintain idle. The ECU uses the Idle Speed Control (ISC) stepper motor to hold the idle speed as constant as possible. The ECU counts on the ISC being in the center of its operating range to have as much control over the idle as possible. While the BISS may have worked fine on a stock car, as soon as you start increasing airflow, you can push the system to the point where the BISS is not bypassing the proper amount of air past the throttle, so the ECU has to push the ISC stepper motor past the halfway point to maintain proper idle speed. Stalling happens if the BISS is set wrong, the ECU pushes the ISC to full lock, and can't push it any farther, and full lock of the ISC is not giving enough airflow to keep the engine running."

While the blown turbo probably wasn't helping your issue, the ISC and BISS still need to be set correctly.