Not hitting full boost anymore

[wootwoot]

Hello AZ, I have a 2007 Audi A4 Tip with a HFC, FMIC, and a JHM stage 1 tune on 91 octane, 90k miles. My car hasn't been boosting anything more than 18 pounds for a while. The car has been checked for boost leaks from a very competent shop and everything checks out. The cam follower has been changed multiple times and I am running a catch can so it's not a PCV issue. Any thoughts on what I could check next?

[Denio24]

The only thing i can think of is if your boost gauge is not working properly or if your wastegate actuator is not functioning properly. Check for vac leaks on the wastegate solenoid, check resistance on the solenoid, and check the wastegate adjustment nut. There is a good diy here on AZ that tells yoy how to adjust the nut as well.

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[seandon_792]

I would still check your DV personally for any rips or tears if you're running the stock one.


B7 S-line 2.0

[Lockon_B7]

I would still check your DV personally for any rips or tears if you're running the stock one.


B7 S-line 2.0

This, if it's torn, go DV+ from GFB.

[Gotpsi2008]

Hello AZ, I have a 2007 Audi A4 Tip with a HFC, FMIC, and a JHM stage 1 tune on 91 octane, 90k miles. My car hasn't been boosting anything more than 18 pounds for a while. The car has been checked for boost leaks from a very competent shop and everything checks out. The cam follower has been changed multiple times and I am running a catch can so it's not a PCV issue. Any thoughts on what I could check next?

What did you used to boost at?? I have everything you have minus the tip, HFC (I have a JHM test), and the fmic, and I spike at 18.8 and hold 17-17.5

[AJacksA4]

Did the boost pressure change after you flashed to JHM? I spike at 18 pounds and I'm JHM stage 2. My boost pressure decreased after switching to JHM but the car got quicker. I've always thought of it as normal.

[Gotpsi2008]

Did the boost pressure change after you flashed to JHM? I spike at 18 pounds and I'm JHM stage 2. My boost pressure decreased after switching to JHM but the car got quicker. I've always thought of it as normal.

Did you go from oem tune to JHM?

[AJacksA4]

Did you go from oem tune to JHM?

Lol no, I went from Revo stage 1 -> JHM stage 1 -> stage 2. With Revo I spiked at 22psi

[B7OrangeA4]

Lol no, I went from Revo stage 1 -> JHM stage 1 -> stage 2. With Revo I spiked at 22psi

Same series except for revo stage 2. I spike 19-20 psi and tapper off to 15-17 with the stock diverter valve and with the gfb dv+ i spike 20-21 psi and tapper off to 16-17 psi

[Rulty]

If you started boosting lower right after the tune switch I would be tempted to blame that, after all tunes are different. The one thing that I would check is actually the serp belt. I got flashed to JHM from stock and only hit 15 psi or so . after wat hing my car run I saw my tensioner moving back and forth so I replaced that and the serp belt. Took it out for a drive and hit 18 or so and after a while I was hitting peaking 22. Not sure why the serp belt would cause this but it may be an easy fix for ya!

[JDillon15]

If you started boosting lower right after the tune switch I would be tempted to blame that, after all tunes are different. The one thing that I would check is actually the serp belt. I got flashed to JHM from stock and only hit 15 psi or so . after wat hing my car run I saw my tensioner moving back and forth so I replaced that and the serp belt. Took it out for a drive and hit 18 or so and after a while I was hitting peaking 22. Not sure why the serp belt would cause this but it may be an easy fix for ya!

That's very interesting. I may need to check my belt as I took it off to replace the thermostat and have been boosting lower (max 18 vs 21 before). I think I also read, your valve cover might have something to do with it as well.


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[Biged243]

This, if it's torn, go DV+ from GFB.

It doesn't play nice with the tune, plenty of post about it.

[Axis]

It doesn't play nice with the tune, plenty of post about it.

I run it witout any issues but I did read people having some problems on Revo iirc.

[Biged243]

I run it witout any issues but I did read people having some problems on Revo iirc.

http://www.audizine.com/forum/showth...-vs-Revision-D

I remembered it wrong Jhm doesn't recommend it.

[wootwoot]

http://www.audizine.com/forum/showth...-vs-Revision-D

I remembered it wrong Jhm doesn't recommend it.

That's good information. I had lost some boost and swapped to the GFB DV+ thinking my DV might have been bad. It worked well at first but boost went from 20 to 18 peak. My shop found a small boost leak and fixed it but I still only boost 18. I may have to swap in a stock DV for the GFB and see if boost returns. It may explain my poor gas mileage as well, 20mpg the past 6 months.

- - - Updated - - -

The only thing i can think of is if your boost gauge is not working properly or if your wastegate actuator is not functioning properly. Check for vac leaks on the wastegate solenoid, check resistance on the solenoid, and check the wastegate adjustment nut. There is a good diy here on AZ that tells yoy how to adjust the nut as well.

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Its funny you mention this, I thought about adjusting the wastegate nut to see if boost would get back to normal.

[Jey4]

I had the wastegate issue and went from 12psi to 17psi after adjusting. I'm on the Apr tune and I've read I should be spiking at 20. Weird is I don't spike, I hit 17psi and it just stays steady there with no spike. Makes me wonder if something is still not right.

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[wootwoot]

Ordered a rev D DV. I'll install it this week and see if my boost returns, if not I may start looking at the wastegate adjustment.