High boost at start
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High boost at start
I'm having an issue where my boost reads 10.0-11.0 at start up then climbs up into the 20s as I drive. If I come to a stop or go below 5 mph the boost reading drops to 0. Normally the boost reading shows a range of 0 to 6 or 7 and up to 12-14 if I get into the throttle too much. Its not as simple as a bad reading, I can tell the truck is more responsive with the higher boost.
I've replaced the up-pipes, boots, ICP, IPR and have the EBPV unplugged. I can't recreate the condition so troubleshooting has been a pain. Any help or ideas would be great.
2002 F350
4 inch turbo back
AFE open filter
Edge programmer
All else is stock
I've replaced the up-pipes, boots, ICP, IPR and have the EBPV unplugged. I can't recreate the condition so troubleshooting has been a pain. Any help or ideas would be great.
2002 F350
4 inch turbo back
AFE open filter
Edge programmer
All else is stock
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New User
Joined: Aug 2014
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I'm going off the Edge programmer so I think it's getting input from the MAP sensor.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Ah.... With everything you describe, it's more likely you have something going on with a connection, the MAP sensor, or a combination of problems that involve a boost leak. There is no method I can think of to actually build 10 PSI boost at idle.
Post Fiend
Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
Impossible to build that much boost at idle. Its an electrical issue somewhere. If your Edge is reading it, then so is the PCM.
Which makes sense as to why the truck feels snappier. The tuning by default limits the fuel in low boost situations in order to reduce tailpipe emissions and black smoke. But if the PCM sees higher boost, those fueling restrictions are eliminated. So your truck feels quicker as a result.
Which makes sense as to why the truck feels snappier. The tuning by default limits the fuel in low boost situations in order to reduce tailpipe emissions and black smoke. But if the PCM sees higher boost, those fueling restrictions are eliminated. So your truck feels quicker as a result.
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I'll double check all the connections, maybe something is loose. Other than the MAP sensor are there other sensors that influence boost pressure and could apply in my case?
Thanks for all the feedback
Thanks for all the feedback
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Post Fiend
Joined: Sep 2003
Posts: 6,096
Likes: 26
From: Mesa AZ
Correct. My Bully Dog programmers and chips did the same thing. They modify the look up tables for things like MAP to get the PCM to offer up more fuel then necessary. Depending on the setting, I'd see boost readings on my AE ranging from -5 to 15 psi at idle. That is why I dislike many of those programmers.
Clever tuners will also modify the MAP table to work around the defueling issue at higher boost levels but they do it in such as way as to preserve the absolute value of the reading.
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