Audi TT Forum banner
1 - 20 of 39 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter · #1 ·
Hi All,

I did a little search but can't find any specific information on this situation so here's a new post. Forgive any naivety here as I'm still new :)

My understanding is that the N75 valve on my 1.8t BAM car is basically the factory boost control valve that works in conjunction with the ECU to control boost via the waste gate.

Now I am looking at an Innovate Motorsport SCG-1 boost controller and gauge. For a couple of reasons, partly to display more info from the car but also to be able to cap or cut boost in certain conditions and have the control in the car. With the stock setup this can only be controlled in the ECU programming and I don't have software for that (can anyone recommend any?).

So the question... can I run both the N75 and the SCG-1 on the same car?

I'm thinking theoretically yes, but I am not sure how they might interact or annoy each other?

Thanks in advance
 

·
Registered
Joined
·
11,964 Posts
If the boost is cut by a method that the ECU isn't aware of, I'm sure that will throw an error.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #3 ·
If the boost is cut by a method that the ECU isn't aware of, I'm sure that will throw an error.
This is the sort of thing I was thinking might happen. But then I was also thinking, surely all cars with a turbo have some kind of factory boost control so in what application would you use the SCG-1?
 

·
Registered
Joined
·
129 Posts
This is the sort of thing I was thinking might happen. But then I was also thinking, surely all cars with a turbo have some kind of factory boost control so in what application would you use the SCG-1?
Only when turbo charging a car that doesn't have any turbo version from factory. Even then I would try to find aftermarket ECU that can do it, and also control timing and fueling and not rely on factory ECU being up to task...
 

·
Registered
Joined
·
9,906 Posts
people have fit manual boost controllers in parallel with the N75 so you can lower the spring and divert more air to the actuator, but it is usually for odd setups which don't seem to be able to control the boost pressure.

some people put a simple push button on the dash which is in series with one of the wires to the N75 connector. so they can run on actuator pressure only.

or

it is possible to get a switchable map, I haven't done it myself, but Bill maps some of the bigger setups with several maps, switchable with a pedals
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #6 ·
people have fit manual boost controllers in parallel with the N75 so you can lower the spring and divert more air to the actuator, but it is usually for odd setups which don't seem to be able to control the boost pressure.

some people put a simple push button on the dash which is in series with one of the wires to the N75 connector. so they can run on actuator pressure only.

or

it is possible to get a switchable map, I haven't done it myself, but Bill maps some of the bigger setups with several maps, switchable with a pedals
Thanks.

Bill mapped mine partially. I had some issues so we didn’t complete. But ever since being there I have an issue that I can’t identify. My boat gauge tracked up to 1.9bar peak pressure which is massively over the readouts he provided. I don’t know why but it’s hard to drive it to test and regulate the boost with my right foot… nay impossible.

Just looking at options.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
9,906 Posts
if the issues are fixed then get the mapping finished? you shouldn't try and compensate something, or map around something - that's an issue - it will be like hitting all the balls right to compensate always hooking the ball :D :D
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #8 ·
if the issues are fixed then get the mapping finished? you shouldn't try and compensate something, or map around something - that's an issue - it will be like hitting all the balls right to compensate always hooking the ball :D :D
Yes of course agreed. But at the moment I have no way to compensate / control the boost so I can find out what the physical problem is (assuming the map is working) and I am sure if I take it back to Badger right now he won’t be happy. It’s a full days round trip to get it to badger also and I’d have to take it in the trailer again.

Bit stuck at the mo.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3,133 Posts
Connect the boost pipe straight to the waste gate actuator and it should run on 7 ish psi or use a manual boost controller until you can get it sorted
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #10 ·
Connect the boost pipe straight to the waste gate actuator and it should run on 7 ish psi or use a manual boost controller until you can get it sorted
It does but then I still can’t find what’s causing the over boost :)


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3,133 Posts
If it runs at 7psi without the N75 then fit a new genuine N75. Or even try a £12 one from ebay just to see if it's any different.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #12 ·
If it runs at 7psi without the N75 then fit a new genuine N75. Or even try a £12 one from ebay just to see if it's any different.
Yea so I changed the original because it was full of oil (turbo was crapping oil into my intake that was the original issue that started this). Bill said the new one was shit and put a new OE one on when it was there. Subsequently I’ve also borrowed one from another car. I’ve now tried running with all 4, same issue.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3,133 Posts
Check the waste gate crack pressure. It should start to move at 6psi.

When i fitted my new turbo and new waste gate it was opening around 7.5psi and over boosting until the N75 caught up. If you havent got a hand pressure pump back of the adjuster nuts 1 turn at a time and test.
I think mine needed 1 turn to sort it
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #14 ·
Check the waste gate crack pressure. It should start to move at 6psi.

When i fitted my new turbo and new waste gate it was opening around 7.5psi and over boosting until the N75 caught up. If you havent got a hand pressure pump back of the adjuster nuts 1 turn at a time and test.
I think mine needed 1 turn to sort it
Ok sure that’s one thing I haven’t tested exactly like that so I will.

But with the line connected from the charge pipe direct to the actuator my gauge logged a steady 0.5bar. That’s around 7.5psi which on your notes is too much, but that’s a completely rebuilt turbo and that’s exactly the setup when bill mapped it. I could of course turn it down but that doesn’t make sense still as to why it’s a problem all of a sudden


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3,133 Posts
That was the issue i had and backing of the crack pressure calmed the boost onset down.
Maybe the waste gate diaphragm has a leak. Was it new or was your old one re used?
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #16 ·
It was a new actuator. Turbo Dynamics rebuilt it but in reality we had to change so many parts it’s almost all new. Even one of the housings had to be replaced.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3,133 Posts
I rebuilt my turbo with a new CHRA, hotside and actuator. I set the actuator crack pressure on the bench before fitting but my gauge was not accurate so boost onset was a bit fierce.
Worth looking at yours.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #18 ·
Indeed my gauge could be off but it is a decent one not a china special. - Innovate Motorsports.

Dis there a way I can check the boost pressure in VCDS by reading values in/out of the n75 do you know?


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3,133 Posts
You can read boost pressure at the MAP on the charge pipe circuit with VCDS
I use Torque Pro app to display boost pressure if i think i have an issue. Can view in real time.
This will be the pressure to the N75 but you won't know how much it's venting to the tip or pressure at the waste gate. Thats controlled by the ECU map and N75 duty cycle setting depending on readings from the MAP and the RPM. But you have tried several N75 and have no fault codes so can probably rule this out
 

·
Registered
Joined
·
9,906 Posts
In not an expert but

1. what modifications (even replacement parts) do you have?

2. And what issues stopped the mapping?

3 what logs have you created?

4. What is the actuator only pressure (electronically disconnect the n75 and it'll bypass the valve and you'll get 0% wgdc as David said above 6(ish)psi


Incidentally, bypassing the N75 with a parallel MBC / EBC won't help you diagnose why it's overboostig, it will just stop it going over whatever you set.

I removed one of my springs in my actuator as the default was 15psi, which worked fine if I was booting it in the right gear, but when the maximum flow was met the boost hit the 35psi pin - I was also getting similar issues if⁷⁷ I floored it in a high gear. Eg if I put my foot flat in 5th at 1500rpm it couldn't do anything with the air, so just built up pressure

I sorted most of this out, but was just too highly strung. All my boost issues were caused by a non standard actuator, which throws out the PID mapping tables.... so you need to limit the wastegate duty.
 
1 - 20 of 39 Posts
Top