Rough idle when cold

Tiny
HUMMERZDCA
  • MEMBER
  • 2004 MAZDA RX8
  • 55,000 MILES
Hello, my RX8 idles (surges) rough when cold, but if I push in the clutch it stops, let it out, it starts again. After about 10 min. Warm, it doesn't do it any more. Trying to find some elec. Switch/circuit related to cold idle somewhere.
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Tuesday, July 30th, 2013 AT 10:44 AM

5 Replies

Tiny
KHLOW2008
  • EXPERT
Hello,

It sounds like you have a vacuum leak or a mass airflow sensor that needs to be replaced, Here are two guides to help you confirm the issue.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

and

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Refer to chart for possible cause.
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Thursday, August 1st, 2013 AT 12:03 PM
Tiny
HUMMERZDCA
  • MEMBER
Okay, thanks for the reply, but: it immediately stops if I press in the clutch, begins again when I let it out. Once the engine is warm it never does it again the rest of the day. It only happens when the engine is cold, once warm never again so I did the vacuum leak test and found the air intake tube had a crack. Once I replaced it the problem went away. Thanks guys!
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Thursday, August 1st, 2013 AT 12:44 PM
Tiny
KHLOW2008
  • EXPERT
Use 2CarPros anytime, we are here to help. Please tell a friend.

Cheers
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Friday, August 2nd, 2013 AT 7:33 AM
Tiny
AIRMAN07
  • MEMBER
  • 2007 MAZDA RX8
07 rx8, engine light flashing, left work, idle rough and wont stay running at idle by itself. Cat. Converter glowing red, pipe was clogged from Catalytic interior busted up, oxygen sensor melted. Had diag, run on it while I kept it running"#2 missing and running lean". I Gutted converter, Replaced all plugs, 2 coils had white burn mark circles, replaced those. Car starts better, smooth at high rpm. Still won't idle on its own, rough idle, white to bluish exahaust, "guess from being gutted, didnt do it before, expected"Eng light still flashing. Going to put new caty on it. Am I missing anything else? And for ref, What is fireing order on coils and eng block? Coils front to rear and block, Trailing plugs front to rear and Leading plugs front to rear. Please help! Wifes car, very expensive, have to do myself, hard cause im disabled. Right leg. Im new to rotor eng, but eaiser for me to work on. Again, wht am I missing. And Thank you for any info! Not sure of catagories.
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Wednesday, March 29th, 2017 AT 2:58 PM (Merged)
Tiny
KHLOW2008
  • EXPERT
Here are the diagrams for the firing order.

When misfiring occurs, the cat converter would glow red while engine is running due to excessive fuel getting to it and it is being overworked.

What was the EXACT trouble codes retrieved for the CEL indicating before gutting the cat converter?
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Wednesday, March 29th, 2017 AT 2:58 PM (Merged)

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