Loss of Boost

[Jeffspeed3]

Is anyone else having problems with a sudden loss of boost. This happens quite suddenly, usually in 5th gear around 5700 rpm under load. It's quite violent when it does this. I have a 2007 Speed3 with the only mod being a Cobb SRI-----

Thanks Jeff

Ps; This only happens occasionally, and never in the lower gears.

 

[SallySpeed3]

Thats because our small turbo loses efficiency around 5500 rpms. After that it just blows hot air. It's completely normal. With some mods and tuning you won't experience such a drastic loss of power after the 5.5 mark. Just adjust your shifting and it shouldn't bother you.

 

[robin2660]

Thats because our small turbo loses efficiency around 5500 rpms. After that it just blows hot air. It's completely normal. With some mods and tuning you won't experience such a drastic loss of power after the 5.5 mark. Just adjust your shifting and it shouldn't bother you.

But OP said, "It's quite violent when it does this"

I don't think the drop-off would normally be considered violent. It also normally happens in all gears in our cars.

 

[MSMS3]

OP: Can you please be a bit more specific in your description? When you say loss of boost, do you have a boost gauge? If so, what is the gauge reading right before this "loss" and then when it happens?

When you say it is "quite violent," please describe what is happening, your sense, any changes, etc.

For instance, and I do not want to plant any possibility in you head -- we need more facts, what are the operating conditions, such as outside temperature. What sounds, if any does it make?

Does this happen just one time, a single "violent" event when you get above 5,500 rpm in the higher gears, or are there a serious of "stutters" or other changes, etc.?

How long has your SRI been installed and how long (time and miles) have you been driving the car before you noticed this change?

More info please. The more detailed your description the better is the chance we can help you.

 

[sick_role]

Not to Pan Am 103 this thing - but the same thing may happen to me under different circumstances; I have zero mods right now and it occurs under very light load (3k or under). Cruising in 6th and maintaining constant speeds between 60-75 (but sometimes it happens at slower speeds). my foot barely on the pedal...I don't know what it is, but my car will "chug" a single time. it is very abrupt, like a brake check. no idea what this is but it doesn't seem good and is seemingly random.

EDIT: it's winter here. low teens for temps but my car is plenty warmed up whenever this happens.

 

[anm6]

Hmm guys sounds like the car is hitting fuel cut.. My DSM used to have that till I swapped fuel pumps.. But that was also at 24PSI. Stock we are only 15?