Sporatic timing at idle - Tuning Forum

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Sporatic timing at idle
Thursday, April 05, 2012 11:05 AM
I've been fighting a battle with irratic idle for years on my 98 Sunfire GT, and a guy from school was able to hook up a monitor to it to see what the sensors were doing. Once the initial warm up idle came down, my timing was all over the place at idle, going from +25+ down to +10 or more very rapidly. Any ideas what could cause such random timing changes in a quick fashion? I replaced the cams almost 6 years ago with 375 lift and 200 degree duration on both intake and exhaust. I don't normally throw codes unless it's really cold out and the car idles for a very long time (10+ min it'll throw a P0300 code).




Re: Sporatic timing at idle
Tuesday, April 17, 2012 11:18 AM
Pcm will use the Spark to try and stable the Idle which is why you are probably seeing erratic Spark.
Besure there are no Vac. leaks or restrictions (like hose to map etc )
This started after Cam replacement?
Tuned for Different Cams?



http://www.weatherallsautomotive.com http://www.planethax.com/j-body
Re: Sporatic timing at idle
Friday, April 20, 2012 6:55 PM
I pinched the Map hose and it ran worse. This did start after cams, I did not retune, as was told I didn't have to. I do have a feeling that'll have to happen though.



Re: Sporatic timing at idle
Friday, April 20, 2012 7:02 PM
My guess is fueling is off with the cams and no tune. I have seen bad feuling cause this exact thing. Seeing as you pinched the map hose and it got worse supports this as idle fueling is controlled by map sensor.



FU Tuning



Re: Sporatic timing at idle
Saturday, April 21, 2012 9:38 AM
Is it possible to have a bad fuel injector too? Once I'm out of idle, things are fine, and the power really starts to be noticed above 2500 RPM.



Re: Sporatic timing at idle
Saturday, April 21, 2012 10:25 AM
Ender_Wiggin wrote:

Is it possible to have a bad fuel injector too? Once I'm out of idle, things are fine, and the power really starts to be noticed above 2500 RPM.
It needs a tune.....



P&P Tuning
420.5whp / 359.8wtq

Re: Sporatic timing at idle
Monday, April 23, 2012 12:51 PM
I was hoping not to hear that, anyone in the Fort Wayne, IN area who can?



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