PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

"cruise control" effect?

Old Feb 5, 2003 | 07:53 PM
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Default "cruise control" effect?

On level ground my car will maintain about 30MPH w/my foot off the gas <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> When comming to a stop I can feel each downshift, once stopped the idle will return to normal. As soon as I take my foot off the brake the idle will shoot up and I'm in cruise control mode again. Also, it idles very nice in park, but when put into gear the idle will raise, slam into gear and then settle back down.

I have a C1 cam and it was dyno tuned by a local shop using LS1 Edit. I tried backing the idle screw off, that didn't seem to help. I did notice the hole in the throttle body is larger than 1/4 inch (5/16?).

Could the hole be too large? I do not have auto tap so I don't know what my IAC counts are. I do have another throttle body, should I barrow auto tap and monitor IAC counts while incresing hole size. TIA <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
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Old Feb 5, 2003 | 08:33 PM
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Default Re: "cruise control" effect?

Maybe have a vacuum leak?? Or posibly a failing iac?
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Old Feb 5, 2003 | 09:18 PM
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Default Re: "cruise control" effect?

Sounds like you have too much air getting in.

If you have a combination of the TB being drilled, and LS1 edit to increase air flow, you may have too much. You are showing all the signs of too much air.
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Old Feb 5, 2003 | 09:34 PM
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Default Re: "cruise control" effect?

sounds like symptons of drilling the TB hole to much...

dont worry I have it also.. ill put my ca rin gear and the idle jumps up to like 1200 and the car idles ahead.. If i put my foot on the brake the idle settles down.

The problem is im getting to much air there, but if I close the set screw a little it isnt getting enough air so go figure(car wont even start)
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Old Feb 5, 2003 | 10:15 PM
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Default Re: "cruise control" effect?

Didn't consider a vacuum leak. What are common places to find a vacuum leak on an LS1? Intake? PCV?

I was thinking the hole was too big. 5/16 is probably too big for this cam.
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Old Feb 5, 2003 | 10:25 PM
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Default Re: "cruise control" effect?

mines 1/4th and i thought that was big <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

its more than likely just the hole being to large..

its a couple hoses on top of the engine to check.. Check the little hose at the VERY back of the intake.. if you have swapped intakes to the LS6 you know the one in talking about. Then there is the hose from the TB to the passanger valve cover. Check those

But again its probably just the hole in the TB.. I have the same issue. Its like the car wants to friggin run the 1/4h with no driver once in gear <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" />
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