I was under the impression that my 2000 would only produce 21 PSI before it starts to defuel. Last night I was passing someone on a hill (A PSD) and I thought I saw it go to about 25 PSI. I payed attention on the next hill and I saw it again, Sustained. What gives?

 

Most Cummins go higher than that. Anything over 50 and you should have the head ringed to keep it under control with that pressure. i have an 05 and I see 34 when I get on it. Not sure about your year (dad has a 99) but I'm pretty sure it'll get that high. he has a boost elbo and edge ez, so I'm sure that helps. I wouldn't worry about it there, and I don't think it defuels at that boost. Normally they don't fully fuel untill there's boost. I'm not an expert on that year (or my year) But I think that's right.

 

Since I don't see a box or a boost fooler I would say you wastegate is sticking.

Mine has been running up to 20-21 PSI and popping open and failling rapid to about 18-19 sometimes lower for a second. This only happen for me in 2nd gear where I can build boost fast.

 

Is this a problem?

 

It should be de-fueling and throwing a error code for that much boost... Stock form they only will go to about 21 PSI then throw a overboost code and start de-fueling.

You might check you map sensor & your wastegate... These are the only two thing I know that control boost pressure and defueling...

Unless one of the guru's have got something else?!?!