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Lack of a Cat Cause Rough Idle? by HummelHund
Started on: 11-19-2003 12:13 AM
Replies: 4
Last post by: Xantavar on 11-19-2003 05:59 PM
HummelHund
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Report this Post11-19-2003 12:13 AM Click Here to See the Profile for HummelHundClick Here to Email HummelHundSend a Private Message to HummelHundDirect Link to This Post
My 88's catalytic converter was taken off and replaced with a straight pipe by a previous owner. Could this upset any of the sensors, or could the lack of backpressure put the whole system out of balance in any way? The car idles well, but fluctuates about 100-200rpm. I plan on replacing the pipe with one of Rodney's cat cons soon, but I was wondering what effect the cat had on the engine as a whole.
Thanks!

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RotrexFiero
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Report this Post11-19-2003 07:44 AM Click Here to See the Profile for RotrexFieroClick Here to visit RotrexFiero's HomePageSend a Private Message to RotrexFieroDirect Link to This Post
I did the same and experienced a mild idle problem. The oxygen sensor may not be up to temp, and I know it appears longer to get to temperature. At least my Fiero does idle better with the cat on. I take it off and on all the time for inspections.
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Arns85GT
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Report this Post11-19-2003 12:44 PM Click Here to See the Profile for Arns85GTClick Here to Email Arns85GTSend a Private Message to Arns85GTDirect Link to This Post
When I took off my CAT, it was really nice.

The idle, and low end torque was much stronger and steadier.

If it varies a little, I wouldn't let it worry me.

However, that could be telling you that your spark isn't strong enough.

My idle also improved greatly after I upgraded my coil.

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FleshRocket
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Report this Post11-19-2003 05:57 PM Click Here to See the Profile for FleshRocketSend a Private Message to FleshRocketDirect Link to This Post
My cat is gone and my car idles fine.

If removing the cat caused an idle problem, it's probably because something else is messed up.

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Xantavar
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Report this Post11-19-2003 05:59 PM Click Here to See the Profile for XantavarSend a Private Message to XantavarDirect Link to This Post
My idle always fluctuates 100-200rpm. This is on a 91 Olds Calais 2.5L.

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