Rough cold idle, tuning tips?
Thread Starter
Registered User
Joined: Apr 2001
Posts: 403
From: Tampa, FL
Rough cold idle, tuning tips?
Ever since I've had on the 58mm TB I've gotten a rough idle when cold. The rpms drop to 500 when I turn on the A/C and revs up to 1k then drops then revs etc. until either I hold the gas down or it warms up. Any tips or starting points to help me out? I have shorties, 58mmTB, 1.6 rr's where do I begin to adjust for these? I use tunercat and it's for a '94.
Registered User
Joined: Jan 2001
Posts: 2,148
From: Bay Area, CA
What brand is it? I had to modify my BBK to work properly, most brands are not cast the way they should be, and some of those now that are 'incorrect' used to be ok, but the casts have changed for some reason.
Registered User
Joined: Jan 2001
Posts: 2,148
From: Bay Area, CA
As best I recall the BBK as stock does not even have the bypass hole at all, which is found in the stock unit.
I also used a 1/2" OD copper tube to close up the back.
I also used a 1/2" OD copper tube to close up the back.
<font face="Verdana, Arial" size="2">I'd say the split BLM and IAC are LT1edit issues for sure, never be afraid to share stuff, because you're rarely alone.
The actual IAC passage that needs to be opened is the very small hole pictured here:
http://carprogrammer.com/Z28/PCM/TB/DSCF0706.JPG
I opened it to look like this:
http://carprogrammer.com/Z28/PCM/TB/DSCF0699.JPG
Don't mess with the actual IAC passage. Several other stock pictures here:
http://carprogrammer.com/Z28/PCM/TB/
You basically want to get the air flowing through the triangle pictured here:
http://carprogrammer.com/Z28/PCM/TB/DSCF0704.JPG
And less air in the intake plenum, since rumpy cams introduce reversion like a ****.
Keep me posted,
-Christian
Check out Als' updated page on the IAC passages- really good!
http://members.***.net/chipsbyal/idle.htm
</font>
The actual IAC passage that needs to be opened is the very small hole pictured here:
http://carprogrammer.com/Z28/PCM/TB/DSCF0706.JPG
I opened it to look like this:
http://carprogrammer.com/Z28/PCM/TB/DSCF0699.JPG
Don't mess with the actual IAC passage. Several other stock pictures here:
http://carprogrammer.com/Z28/PCM/TB/
You basically want to get the air flowing through the triangle pictured here:
http://carprogrammer.com/Z28/PCM/TB/DSCF0704.JPG
And less air in the intake plenum, since rumpy cams introduce reversion like a ****.
Keep me posted,
-Christian
Check out Als' updated page on the IAC passages- really good!
http://members.***.net/chipsbyal/idle.htm
</font>
Registered User
Joined: Jan 2001
Posts: 2,148
From: Bay Area, CA
It should hurt the idle consistently, what are your IAC counts compared to before?
With a heads/cam job my car would not idle at full 160 IAC with the BBK in place, but worked fine with the stocker.
I believe I started with an 11/64" drillbit, as well as the tube I mentioned.
With a heads/cam job my car would not idle at full 160 IAC with the BBK in place, but worked fine with the stocker.
I believe I started with an 11/64" drillbit, as well as the tube I mentioned.
Thread Starter
Registered User
Joined: Apr 2001
Posts: 403
From: Tampa, FL
Well it was a long time before I could get around to scanning it..found the IAC was high but I got it down without having to drill a hole. The surging idle is now rare and the car seems to react a lot better when I turn on a/c. Although I barely had time to set it and had to stop before I finished. I think it's still not completely within range. Maybe off by 10 counts or so. I don't quite understand what tube goes where on your fix but the car seems to be okay without it. Thanks
Thread
Thread Starter
Forum
Replies
Last Post
Bignasty85
General 1967-2002 F-Body Tech
12
Mar 3, 2015 04:05 PM
Gtpguy
General 1967-2002 F-Body Tech
48
Jan 26, 2015 04:50 PM