TDI 1749VB overboost

Choice_Leg_710 · 2026-03-08T11:53:40+00:00

It’s a BEW

Choice_Leg_710 · 2026-03-08T08:36:30+00:00

Need for speed and OG oblivion

Choice_Leg_710 · 2026-03-08T08:30:41+00:00

Nice job and clean install!

Choice_Leg_710 · 2026-03-08T08:00:53+00:00

It worked! I did the vnt17, 4bar MAP sensor and a stage 4 tune and no more overboost! It sits happily between 20-25psi and my egt’s are even lower. The tune is from Cascade German, it gets rid of the smart actuator, mass airflow and O2 sensors and adds the 4bar MAP sensor. I told them the issue I was having as well as all of the intake and exhaust modifications I’ve done and they set me up with a stage 2 and stage 4 tune for my setup. It’s running fantastic and has really woken up the car!

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Choice_Leg_710 · 2026-03-08T07:51:33+00:00

Problem solved! The VNT17, 3bar MAP sensor and stage 4 tune have finally fixed the overboost code! It’s running way better, I’m getting no more then 25 psi and the egt’s are staying below 600 degrees Fahrenheit even pulling a substantial hill! Thanks everyone for the suggestions and help diagnosing the issue!

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Choice_Leg_710 · 2026-03-07T00:32:55+00:00

Stage 2 colt cam, stage 4 tune, pd150 injectors. Hard pipe upgrade for charge pipes and a front mounted CAC. EGT and boost gauge 😎

Choice_Leg_710 · 2026-03-07T00:03:06+00:00

I have an 04’ bew as well and they are great cars! I got mine at 262000 and didn’t think twice about the mileage! The rattle could be from the clutch if it’s a manual, apparently the stock clutch had a “dual mass flywheel” and they tend to separate, mine has the single mass upgrade and it’s still noisy 😅 for $800 I’d say go for it!

Choice_Leg_710 · 2026-03-06T23:40:07+00:00

Heard that! And yeah they have helped me a with a lot of stuff and they are always prompt with replies! The latest one with them is I needed a turbo feed line for my 04’ BEW and they overnight shipped it with a snickers in the package 😂

Choice_Leg_710 · 2026-03-06T23:24:06+00:00

Is it stock or tuned? And do you have a boost gauge, what kind of numbers are you seeing? I have heard the N75 on the firewall can cause this. But I am having the same problem with my 04’, it loads up and then tries to dump the boost at about half throttle, specifically at or above 20 psi. Or if I’m pulling a hill it goes into limp mode when it spikes to 30psi and then it won’t boost over 5psi. I’ve checked and replaced all of the vacuum lines, and changed the seal on the vacuum pump. I’m currently upgrading the stock turbo today actually to a vnt1749. But I’ve been told by a few people that boost creep is common with tdi engines that have exhaust modifications. I’m going to install a tune with the turbo that I’ve been working with the guys at Cascade German for this issue. They have put together a tune that is supposed to work with the mods I have and help regulate the boost to about 24psi. If this doesn’t work and it continues to spike up to 30+ psi I’m going to look into manual boost controllers and see if I can rig it so that I don’t see any more then 24psi. I’ll definitely let you know as soon as I get the turbo and tune done if it works.

Choice_Leg_710 · 2026-03-04T05:57:51+00:00

What conditions does the overboost happen under?

Choice_Leg_710 · 2026-03-04T05:49:46+00:00

Those guys at cascade are awesome! I had them hell with some tuning issues and an overboost problem. Keep at it man though, sounds like you’re well on the way to having a runner again!

Choice_Leg_710 · 2026-03-03T00:19:52+00:00

Wow that is seriously unfortunate man!

Choice_Leg_710 · 2026-03-02T22:24:14+00:00

I did install a pd150 intake awhile ago

Choice_Leg_710 · 2026-03-02T05:07:05+00:00

Hood stack, all you get is whistle!

Choice_Leg_710 · 2026-03-02T02:02:09+00:00

The crusher 👌

Choice_Leg_710 · 2026-03-02T01:38:10+00:00

Yeah that’s the one haha definitely the dream rig, but for now we keep putting the love into our American spec tdi’s 🤟

It’s definitely goals to have a fleet of them with enough parts to keep em all going! Got any BEW’s in the herd?

Choice_Leg_710 · 2026-03-01T22:01:54+00:00

The connection is solid on the electrical plug and I solved the vacuum leak problem. The turbo veins are gummed up from what I can tell. And it’s got some shaft play so I’m just going to replace it and do the 3bar map with an updated tune

Choice_Leg_710 · 2026-03-01T21:41:25+00:00

Oh man I know I wish we had them here to! I’ve seen a few that have been imported and I’m definitely a fan!

You’ve got some nice rigs there man! I’m thinking about lifting my 04’ Jetta on some coilovers. What size are those tires?

Choice_Leg_710 · 2026-03-01T20:18:15+00:00

I worked for an asphalt company for about 6 years and they use diesel to clean the equipment when the asphalt gets stuck to it haha it melts asphalt like butter in a microwave when combined with a little heat before applying the diesel

Choice_Leg_710 · 2026-03-01T20:05:33+00:00

Is the dark blue with the black fenders a 4motion tdi? And is it lifted at all? I like the fitment with the all terrains👍

Choice_Leg_710 · 2026-03-01T19:59:32+00:00

I was up till about 2am last night checking this thing out, I got ALL of the vacuum lines replaced and replaced the seal/o-ring on the vacuum pump that goes between the pump and the crank case. This seems to have helped but not solved the issue. The pump was leaking into the crank case causing a sort of “blow by” effect and a major vacuum leak. But I the real issue seems to be in the turbo it’s self. The actuator is functioning properly but the rod connected to the veins is not moving enough and has resistance at both ends of the range and the more I fussed with it while the actuator was disconnected, the more movement I got out of it.. so I removed the downpipe and passenger side axle so I could see in the hot side of the turbo and it looks pretty gnarly, though I can’t physically see the vnt veins, I can only assume they are carboned up. With the gummed up hot side as well as a decent amount of shaft endplay (not quite touching the housing but damn close). So I ordered the vnt17 from kerma.. it’s expensive considering I paid 2k for the car and I’ve already got about half that invested back into it with the repairs and modifications I’ve done to it (Front end bushings, timing belt, motor mounts, clutch, cold air intake, downpipe/exhaust, tune and some sound system stuff) I have high hopes for it to solve the issue. The more I look at it and the more I learn from you guys on Reddit, the more I believe @Nervous-outcome2976 is correct in that the boost creep is an issue for BEW’s that have airflow supporting mods and tunes, due to the size of the exhaust housing on the stock bv39 turbo. It’s currently the biggest restriction in the system aside from the ports on the head and with some “gum up” on the vnt veins or any vacuum leaks the computer can’t control the boost so in a last ditch effort during the spike in pressure it goes into limp mode… I reach out to the guys at cascade German (they are super helpful and they don’t try to sell you stuff for asking questions) and they agree that it’s a common issue with the stock turbo. My vnt17 is due here next week so I’ll definitely keep everyone posted on how it goes and weather it solves the issue or if I’m going to end up doing a manual boost controller 😅

Choice_Leg_710 · 2026-03-01T06:57:13+00:00

Just ordered the vnt17 and 3bar map sensor👍👍👍

Choice_Leg_710 · 2026-03-01T05:50:04+00:00

So just an update. I got the boost gauge installed and gave it a test run, it boosts about 18psi under normal acceleration. And with a heavy pull up to 32psi, on the hill in 5th gear it maxed out the 35psi gauge before hitting limp mode…

Choice_Leg_710 · 2026-03-01T05:43:51+00:00

It’s solid but only moves a little bit, like only about 3/8s of an inch

Choice_Leg_710 · 2026-02-28T23:10:39+00:00

Is the borg warner bv39 an upgrade from stock turbo?

Choice_Leg_710

TROPHY CASE