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Full boost to no boost

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5
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Location
Dundee, UK
#1
While driving take off in 1st and 2nd are fine half way through third all boost power is gone no warning light nothing just no power like being in limp mode, when car is restarted everything is back to normal until I hit 3rd gear again. If I only give it half throttle it's fine but same in 4th 5th and 6th under full throttle. It is mountune stage 1 and has only started recently. Rather annoying when your overtaking someone on a single carriageway and you lose all power half way through and need to fall back.

Anyone got any ideas it's starting to bug me everything seems to be plugged in and connected properly also no errors in obd reader.
 


Messages
179
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165
Location
Virginia
#2
Mountune keeps boost limiting in 1st and 2nd gear, so it sounds like the issue is only happening when it's allowed to use full boost. There's probably a dozen things it could be (boost leak, wastegate actuator, leaking blow-off valve, etc.)... without any CELs or codes, going to need a better picture of what's going on from a data log.

Are you seeing a low boost peak? Is it showing negative timing? Knock? Low quality fuel?
 


Messages
179
Likes
165
Location
Virginia
#4
Have a look at ignition correction (positive numbers are good, negative means it’s pulling power) on all four cylinders. Likewise take a look at knock count. Finally, “fuel lrn ratio.” These are all parameters you can find for gauges in your Accessport.

Also, when you say boost peak looks normal, you mean it’s still normal even when it’s losing power? That wouldn’t make a lot of sense...
 


OP
PGoReMiiX
Messages
5
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0
Location
Dundee, UK
Thread Starter #5
Have a look at ignition correction (positive numbers are good, negative means it’s pulling power) on all four cylinders. Likewise take a look at knock count. Finally, “fuel lrn ratio.” These are all parameters you can find for gauges in your Accessport.

Also, when you say boost peak looks normal, you mean it’s still normal even when it’s losing power? That wouldn’t make a lot of sense...
I mean feels normal i dont have an accessport so wont be able to anytbing that that
 


OP
PGoReMiiX
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Location
Dundee, UK
Thread Starter #6
Was just really looking to see if anyone had any idea what it could be
 


Messages
179
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165
Location
Virginia
#7
Was just really looking to see if anyone had any idea what it could be
I had assumed you were running a Mountune OTS tune, but that was an incorrect assumption of mine. Let me back up.

The factory tune limits boost in 1st and 2nd gears (8 psi in first, and I think 15 psi in 2nd). In third gear it should allow full boost (~21 psi), but clearly this is not the case with whatever is going on with your car. The #1 cause of this is a boost leak (usually a loose hose clamp). It can also be a faulty blow-off valve or a faulty wastegate actuator. For a loose hose, you can investigate by going over the entire intake system from the turbo to the throttle body, and make sure every clamp is tight. Don't forget to check the sound symposer too (the little box to the right of the throttle body)

If it's not just a loose hose, then there's not much else I can do besides guess. At that point you really should take it to someone that can plug in to the car and pull the data to see what's going on.
 


OP
PGoReMiiX
Messages
5
Likes
0
Location
Dundee, UK
Thread Starter #8
I had assumed you were running a Mountune OTS tune, but that was an incorrect assumption of mine. Let me back up.

The factory tune limits boost in 1st and 2nd gears (8 psi in first, and I think 15 psi in 2nd). In third gear it should allow full boost (~21 psi), but clearly this is not the case with whatever is going on with your car. The #1 cause of this is a boost leak (usually a loose hose clamp). It can also be a faulty blow-off valve or a faulty wastegate actuator. For a loose hose, you can investigate by going over the entire intake system from the turbo to the throttle body, and make sure every clamp is tight. Don't forget to check the sound symposer too (the little box to the right of the throttle body)

If it's not just a loose hose, then there's not much else I can do besides guess. At that point you really should take it to someone that can plug in to the car and pull the data to see what's going on.
Thanks, from what I can see from top view everything is tight and suffered from a boost leak a few months back but got that sorted I'll try find someone with either an obd2 or accessport

Thanks for you help
 




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