Bad idling issues, can't figure it out

[Catbox_95]

I can't get my car to idle right. It is low, and I don't think the a/f ratio is correct. But then I was reading that the ECU will automatically try to achieve stoichiometric, and my wideband O2 is registering between 14 and 15. If this is true, then why do we have the capability to tune the a/f ratio at idle on both the MAFT and SAFC-2? Shouldn't we just leave these set to 0 and let the ECU bring it to 14.7 on it's own?

But the problem with the idle is, low rpm, rough, and frequent dying. I've tried adjusting the idle set screw, but this only changes the rpm for a few seconds, then comes back down. Remember, it's a 1G throttle body, not a 2G.

You can check out my mods list, but the important thing to know is this:

1G throttle body
GM MAF with MAFT
SAFC-2
Wideband O2

 

[90blacktsiawd]

Yes there is a point to being able to adjust the idle. I can't speak for a 2g but i had to lean out the idle a bit to get the fuel trim right. Of course 1g's get a low fuel trim which lets you know the ratio at idle.

As for the idle it sounds like you aren't grounding out the ecu whe you try to adjust the idle. If you adjust the idle without grounding out the ecu plug and diagnostic port the ecu will see what you are doing and compensate for it to bring it back to what it thinks it should be rather quickly. Here is a link to how to properly adjust your idle. Akthough i'm sure there is a more detialed and pic filled explaination on this site.

 

[Catbox_95]

Link???

 

[90blacktsiawd]

sorry about that i got distracted there. http://www.vfaq.com/mods/BISS-2G.html there you go. Hope it helps. Am i correct in thinking you weren't grounding out the 2 plugs?

 

[Catbox_95]

I would have to say yes, you are correct in thinking I wasn't grounding out the 2 plugs. Especially since I don't really know what that means! I am going to check out the link you sent me to see if I can figure it out.

-Thanks

 

[Catbox_95]

So, that really sucks. I mean the part about needing a scan tool.

And now, how do I even know if I need to adjust the BISS? What about just turning the idle set screw that goes to the linkage?

Seems to me that there are too many variables, and I don't know where to begin!

 

[90blacktsiawd]

BISS = Base Idle Set Screw

You don't need a scan tool a logger will do the trick or a set of alligator clips. Actually 2 sets of clips. I'm not sure exactically which pin needs to be grounded on the diagnostic port but i can tell you about the one in the engine bay. It's a small clip about 1"x2" next to the battery on the fire wall. It will have a cap over it that must be taken off and then you can see a pin inside. Attach one end of some alligator clips to it and the the other to any ground or even the negative battery terminal. I'm certian you can find pics on this site if you look.

 

[90blacktsiawd]

And how do you know you need to adjust the idle. Well is your idle right? If not it probably needs to be adjusted. If you just for some reason disconected the battery or reset the ecu it will take alittle while for the ecu to re-learn what it should be doing.

 

[1gTurboTuner]

I had the same problem about a week ago and it turned out to be the idle control motor on the bottom of the throttle body. I found that out by sending it to a shop to hook up to their computer since i dont have any logger of any kind.... but just a thought, might be able to pick one up from a buddie or at a salvage yard for like 10 bucks.
my 2 cents

good luck,
allan