Ruff Idle
Thread Starter
5th Gear
Joined: Sep 2023
Posts: 5
Likes: 1
Ruff Idle
I have a 2007 Z06 that is cammed and tuned, owned the car about 10 years. Driving it one day it got a miss, I have changed the plugs, cleaned injectors, ran Techron adder, cleaned mass air and throttle body. Hooked it up to a computer and no codes or light, O2 senor was a little sluggish. Installed both O2 sensors and still there. I can start the car, and everything sounds great till you tap the throttle the engine revs up and back down once it comes down it has a ruff idle like a miss. After a few seconds it will smooth out and sounds fine till you tap the throttle again. The car was built and tuned when I bought it, not sure who tuned or what tune is in it and the stamps on the head look like factory heads. Car has 23K on odometer. Any information is greatly appriciated, I don't want to throw money at it.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,432
Likes: 3,981
From: Cape Coral, Florida
It looks like you have a scan tool so why don’t you hook it up and see what your MAF, fuel trims, and O2 sensors are doing…upstream O2’s should be “oscillating” between 200-800 mv’s.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,432
Likes: 3,981
From: Cape Coral, Florida
When you replaced the O2 sensors are they OEM ??…what brand ??…do you mean they are still sluggish after changing ??…MAF (in not speed density tuned) should read the liter displacement of the engine at “hot unloaded” idle…ie…no electrical loads…downstream O2’s should be steady (not oscillating) at about 700-800 mv’s…video below…fuel trims should not be more than plus or minus 10%…with ignition in RUN and engine OFF and scan tool connected the O2’s should read 450mv’s…the bias voltage.
Last edited by C5 Diag; Sep 14, 2023 at 01:00 PM.
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