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Discussion Starter #1
I posted this at the end of my build-thread but I want to make sure I get plenty of input so I'm re-posting it here by itself.

I'm currently in the tuning process following my turbo build and we've been struggling to set up a basic, healthy idle.

I'm throwing a P2195 code which is a front O2 sensor DTC. Here's the description of the code: "A HUGO sensor indicating lean at the end of a test is trying to correct for an over rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time."

I've replaced O2 sensors and Tom has modified 12 tuning files in an attempt to overcome the idle problems. Today I pulled my fuel pump fuse to de-pressurize the fuel tank so I could check my injectors and fuel rail. To my surprise, the idle stumbling completely went away when the fuel pump fuse was pulled. In fact, the idle sounded absolutely awesome for 3-4 minutes til it ran out of gas! This video repeats and demonstrates that phenomenon.

Why would this be? Any thoughts, ideas, or suggestions?

http://youtu.be/ojArEx5-_jY
 

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That head sounds super noisy, just sounds like a super aggressive cam idling. i love that sound lol
 

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have you checked the fuel pressure while running? If its a non return fuel system and you disconnect the fuse for the fuel pump that would disable the system for fuel pressure regulation. Just an idea.
 

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Only thing I could think of that would do that is a dripping fuel injector. Like said above , need to check running fuel rail pressure. Pull the plugs , see which one is wet. When you pull the fuse, it seems the lower pressure makes it spray better. You could also try pulling each inj plug one at a time. Maybe give you an idea of which one it is.
 

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Discussion Starter #6
I talked to Tom this morning and he's having me repeat this exercise while running a datalog. I just did so and shot it off to him. It'll be interesting to get his take on it.


btw...Thanks JGrove for posting a better link to the video. I really need to learn how to do that.
 

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Discussion Starter #8
I know it sounds like there's a lot of cam/head noise but that's actually the timing belt tensioner clacking under the struggling idle. It's also a function of a really bad iPhone video app. I've got OEM cams and the cam gears are pretty much set to zero.
 

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Timing I meant with the bar and peg in place.
I might recheck that and replace that idler pulley if it's making a lot of noise.
 

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I doubt it's the tensioner. It's spring loaded so it moves around if it's clanking it would be broke
 

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Would a misconnected BAP, if you are running one, create this? Like mentioned above it will be good idea to know fuel pressure, too much at idle...
 

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I did a new tune file and we may of had a corrupt tune file , Its rare but happens , things look normal in the logs now and we seem to be moving forward

Tom
 

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Good to hear.
 

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Discussion Starter #14
My idle issues have been perplexing Tom and me for almost a week now. This latest business where it actually ran better with no fuel pump just got a little too wierd. When Tom heard about it he asked me to send him some logs, which I did. He immediatley responded with a "crude test" file to see if perhaps something had gotten corrupted. I loaded it and, sure enough, the engine fired right up and idled smooth as silk. We've spent the remainder of the day fine tuning the idle, which is now beautiful.

Apparently I just had a ghost in the machine!
 
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