Possible under/over boost

Reply Subscribe

Thread Tools

Search this Thread

Sep 17, 2023 | 08:50 AM

JaySVX

Thread Starter

Fleet Mechanic

Joined: Feb 2008

Posts: 1,955

Likes: 6

From: Eastern PA

Possible under/over boost

I get a slight burp at high rpm, and occasional decel sounds. Only code is p0299 which is low turbo pressure, but I just accidently blew off the hot side. I suspect that may have been my fault, it looked like the pipe was backing out.

Videos have sound. Any suggestions on how to properly diagnose what's happening would be appreciated. All stainless pipes and sinister diesel hoses and clamps. No tunes, nothing like that. EGR removed. MAP & VGT recently replaced.

https://i.imgur.com/MoEdxRY.mp4

https://i.imgur.com/EJ0mmL4.mp4

Sep 17, 2023 | 07:57 PM

Toreador_Diesel

FTE Leadership Emeritus

Joined: Sep 2003

Posts: 12,253

Likes: 763

From: Houston, Texas

Reply to my PM and I'll walk you through it. I left you some information.

It sounds like you have some sticky vanes or maybe some crosstalk at your VGT sensor. Did you replace the harness, sensor or both?

Sep 17, 2023 | 08:44 PM

JaySVX

Thread Starter

Fleet Mechanic

Joined: Feb 2008

Posts: 1,955

Likes: 6

From: Eastern PA

Just the sensor. I may need to just run it more. It's been sitting. I ran forscan and the graphs look good as far as I can tell. Maybe it's just me being incompetent at tightening the boots down. I'm almost certain its the hotside left pipe that connets to the intercooler.

I need to get some injector cleaner, it's running on 4 year old diesel. Is diesel kleen still the go-to for addetives?

Sep 17, 2023 | 08:49 PM

JaySVX

Thread Starter

Fleet Mechanic

Joined: Feb 2008

Posts: 1,955

Likes: 6

From: Eastern PA

Quote:

Originally Posted by Toreador_Diesel

Also your pm's are full.

Sep 17, 2023 | 09:18 PM

JaySVX

Thread Starter

Fleet Mechanic

Joined: Feb 2008

Posts: 1,955

Likes: 6

From: Eastern PA

MAP is reading up to 190kpa, that's 27.5psi. So that's normal right?

Sep 17, 2023 | 11:20 PM

Toreador_Diesel

FTE Leadership Emeritus

Joined: Sep 2003

Posts: 12,253

Likes: 763

From: Houston, Texas

You answer mostly lay in the 4 year old diesel. You may also need to clean the turbo. Not hard to do at all.

You will need this fuel additive

Archoil Diesel Fuel System Kit - AR6500 Diesel Treatment (40.6 oz) + AR6400-D Diesel Fuel System Cleaner https://a.co/d/fgqTldi

It works the best. Diesel Kleen worked great when these trucks were new but Archoil works so much better.

Sep 17, 2023 | 11:21 PM

Toreador_Diesel

FTE Leadership Emeritus

Joined: Sep 2003

Posts: 12,253

Likes: 763

From: Houston, Texas

Quote:

Originally Posted by JaySVX

MAP is reading up to 190kpa, that's 27.5psi. So that's normal right?

That's about right although it's slightly higher. Some see as high as 29-30 psi.

Trending Topics

My 1976 F-250

3.9k

263.5k
7.3 or/vs 6.7

21

604
This is prolly a 1 page thread at most

110.3k

6M
Header tube temp question.

16

231
Another Crank no start -- sorry

27

492

Sep 17, 2023 | 11:31 PM

JaySVX

Thread Starter

Fleet Mechanic

Joined: Feb 2008

Posts: 1,955

Likes: 6

From: Eastern PA

Quote:

Originally Posted by Toreador_Diesel

That's about right although it's slightly higher. Some see as high as 29-30 psi.

I could probably account for that with the pressure escaping. The boot not sealing right is acting as a blow-off valve at ~25-27psi. As long as I'm not seeing overboost, I'm happy.

I've had the turbo off many times. I *really* don't want to do it this week. I'm planning to take the truck on a small road trip next weekend, only 100 miles but lots of gear. I'll drive it this week, get some of that addetive in it, fresh fuel. I'm only down to 1/2 tank so 1/2 tank of new fuel plus the additive should do the job. It sounds perfect, runs like a top, just that boot. Which i think is most likely that hot low side, but I can't tell for sure. I just reseated it, cranked it down, and took it out for a spin, but it's still letting excess boost off around 3200-3500rpm.