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Second turbo problems


AMG

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Hi all, I hope someone can shed some light on this as it is doing my head in.

 

Basically my first turbo boosts to about 0.8 bar and then the second turbo does not come online at all. I have checked all the vacuum pipes I can and replaced the IACV with a brand new one. Still no joy.

 

Can anyone give me an idea of the next thing to check or replace?

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what boost are you getting when the 2nd turbo should be online?

 

does it drop off totaly or stay at 0.8?

 

i was having a problem a while ago where when the 2nd turbo should be appearing the boost dropped to 0. turned out just to be a sticky boost valve. after booting it 7-8 times it suddenly worked again.

 

if it stays at 0.8 it could just be a different valve. there are 4 in total. There is a post in the technical section about them. and where they are.

 

it could also be the turbo. but i think it smokes if that happens? not sure as thats never happened to me.

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It could be something simple like a split vacuum hose, I'd double check all the hoses are connected up properly and ideally replace them all with new ones.

 

Some links that may be of help.

 

http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system&highlight=sequential

http://www.mkivsupra.net/vbb/showthread.php?35924-Sequential-turbo-hoses&highlight=sequential

http://www.mkivsupra.net/vbb/showthread.php?27904-Sequential-turbo-problems&highlight=sequential

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what boost are you getting when the 2nd turbo should be online?

 

does it drop off totaly or stay at 0.8?

 

i was having a problem a while ago where when the 2nd turbo should be appearing the boost dropped to 0. turned out just to be a sticky boost valve. after booting it 7-8 times it suddenly worked again.

 

if it stays at 0.8 it could just be a different valve. there are 4 in total. There is a post in the technical section about them. and where they are.

 

it could also be the turbo. but i think it smokes if that happens? not sure as thats never happened to me.

 

 

 

It stays at 0.8 all the way up from 4k. No sign of the second turbo coming in late or even trying to help the first one out. I have given it a few good runs but don't want to push the first too much.

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It could be something simple like a split vacuum hose, I'd double check all the hoses are connected up properly and ideally replace them all with new ones.

 

Some links that may be of help.

 

http://www.mkivsupra.net/vbb/showthread.php?35926-The-sequential-system&highlight=sequential

http://www.mkivsupra.net/vbb/showthread.php?35924-Sequential-turbo-hoses&highlight=sequential

http://www.mkivsupra.net/vbb/showthread.php?27904-Sequential-turbo-problems&highlight=sequential

 

 

Cheers Nic. I think I will replace them all just to confirm that all the hoses are spot on first.

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Try the ttc mod to see if the 2nd turbo is working. are you bpu, what full boost do you normally see?

 

I will give that a go too. Pretty sure the turbo is fine. I normally see 1.45 max. Running hybrids, fmic, fuel pump, air filter, full decat, blitz nur spec, blitz sbc, blitz access ecu.

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Hopefully i will get to try TTC later, all being well. Would it cause many problems, if i like it, running like this all the time? I am thinking fueling problems mainly. Will a blitz access ECU handle it better than the stock ecu?

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The fact you have the blitz access means it can be properly mapped. As long as you do that there will be no issues.

 

Don't push it too hard in TTC. The stock map is very rich and safe. Your current map may be more geared towards performance, giving less headroom :)

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Can it be remapped?

 

Blitz Access cant be remapped, theyre just stock ECUs like TOMS etc, with generic mapping tweaks, ignition advances and suchlike. And its not common to find faults in sequential operation, unless its busted.

As above, TTC mode to see if no2 is working then go from there :)

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Right then, last night i took it out for a run in TTC and...... It worked :D I quite liked how it performed but still would like to get to the bottom of the problem in sequential. I think i will look into the ETTC mod once i have sorted it.

 

Anyway, i have checked all vacuum lines, fitted a brand new IACV, and had success in TTC. Does this just leave the EGBV? That is the only bit that has not been replaced that was bypassed in TTC.

 

I may be wrong though.

Edited by AMG (see edit history)
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do you know how would i check the pressure tank? thanks for the help by the way :)

 

When in TTC mode take the car for a run on boost. Pull over and turn the engine off. If the Actuators are open (the big one underneath the turbos is the easy one to spot) then the pressure tank is holding pressure and it's fine. If it has closed, the pressure tank is goosed.

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When in TTC mode take the car for a run on boost. Pull over and turn the engine off. If the Actuators are open (the big one underneath the turbos is the easy one to spot) then the pressure tank is holding pressure and it's fine. If it has closed, the pressure tank is goosed.

 

I will give that a go and see what i find.

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I will give that a go and see what i find.

 

Just thinking, that was a bit harsh lol. It might not be goosed, it might just be a line has split/disconnected.

 

It most likely won't be the pressure tank as I think that when it is fooked the 2nd tubby will still come online... it'll just be a lot later.

 

It's been a while since I went through all this stuff though.

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