Stumbling Idle Cold Start Fuel Injectors Cleaned

Hey all, I just wanted to put it here for search purposes in case anyone has the same issue in the future. Several months ago, I noticed that after the car (2005 f430) had sat overnight, it would stumble on startup for about 5 seconds. The idle would search up and down (almost like a gallop). It would then settle down before the CEL light went off. It would only do it if I started the car after it had been sitting for about 12 plus hours. At the suggestion of someone here, I pulled the injectors and had them cleaned and flow tested. I was disappointed when they all passed and didn't drip during the test as I thought I would have the same issue upon reinstallation. Fortunately, whatever the issue was, the cleaning (or replacing all the o rings) fixed it. Its been about a week and the car fires up and idles perfectly every time now. It only cost about $20 per injector and a local shop did it in about 6 hours. If you come across a similar problem, take a look at your injectors!

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Does that happen automatically when you unplug the injectors? Also, would it only happen the first start of the day? The cold start condition didn't seem to cause it, it would only happen if it sat overnight or for more than about 24 hours.

 

LOL, neither. I just disconnected them.

 

I definitely should have since the fuel lines were open, but I was just super careful not to accidentally switch the ignition on. Not the smartest . . . but no catastrophe.

That's my guess, the old O-Rings were probably shot. I had no fuel smell before or after though. Whatever it was . . . it seems to have worked.