99 E350, boost leak
 

I have a boost leak that is only when cold, so I suspect the EBPV but I wanted to get your opinions in case its something obvious that I didn't discover in a search. Its also possible that its something else and it has only started since it got cold.

When cold and driving: between 5% and 25% throttle (approximate) I hear a boost leak. If I add more pedal, it goes away. If I drop to idle, it goes away. While its hissing, I have a slightly noticeable reduction in power, kinda like a gas engine running lean.

For instance, on a rural road with varying pedal positions, I'm hearing pssssss-ip. The "psss" part is during 5-25% throttle and the "-ip" part is when I drop to no pedal or accelerate past 25%.

I pulled the doghouse to try and pinpoint the noise, but there was so much noise I couldn't really narrow it down.

Sounds like thats just your EBPV closing while you drive because the PCM doesnt think the motors warm yet. very common. The hiss is just exhaust spilling over the valve. nothing wrong.

A true boost leak would get louder as you get into the throttle and only really be heard under heavy acceleration.

A true boost leak would not come and go either. It either leaks or it doesn't.

That's what I thought, but I did have a cracked compressor housing once that leaked until you got boost and it heated up... kinda like an exhaust manifold crack that is loud when its cold but then goes away when its hot.

Also, what if I told you that this noise started at 100k; about a month ago - and its getting worse :td:

Probably have a clogged EBP sensor pipe. Can either pull it and clean it or just get a new one. When the PCM isnt getting a good signal on exhaust pressure it'll get screwy like this

Try unplugging your EBPV and seeing if the issue goes away...

Ok, that makes sense. Can I leave it unplugged until I clean/replace the tube, or will it set a code? I would hate to have to put electrical tape over the dash light. :)

it will probably throw a code, but the SES shouldn't come on

Great. I'm pulling the doghouse tomorrow if the weather holds out. :c:

I think it sets a soft code on the Superduty's which won't light up the SES but if you check for codes, it will be there... Just unplug it and leave it.