I tried searching about this with no results.

I have a 98 a4 that currently has 203000km. Its running smooth and strong except for my turbo. It has started squealing from the bearing and causes loss of boost in 4th and 5th gear along with excessive play in the the shaft of the turbo's compressor wheel. this started at about 180000km. I have the 150HP AEB model which is drive by cable throttle. It has had its APR chip configured for 1 bar(14.5PSI) since 52000km which claims to be at about 200hp with 240 ft/lbs. The chip does not have EMCS switching options!

I just recieved a New turbo in the mail from Borg Warner which was aparrantly called ko3s which is supposed to be used in 2001+ models. as far as i know my current turbo that is garbage is a ko3 (not an ko3s).

Along with the turbo, I recieved I borla cat back which will be installed at the time of the turbo which will also be accompanied by a new timing belt and water pump/thermostat(done 6000k ago but was missing parts so I put off the timing belt until now)

I have No aftermarket air intake, According to many people the stock airbox can be more efficiant than most. due to cold air directly going to the air box. also still being a ko3s im sure the k&n panel filter that i have is sufficiant.

Now the confusion im in now is, I Have an Gizzmo Electronic Boost Controller I plan on putting in my spare holes next to my seat heater switches in my dash. It will display a real-time psi boost reading along with adjustable PSI settings via a solenoid to switch between the wastgate, turbo housing(intake pressure) and atmosphere to maintain the desired PSI level.
Im aware that APR has changed fuel maps along with timing and so on to acheive a better enviroment to compensate for the extra boost. I call it extra boost because the wastegate is set to open at 11.6PSI stock. So the N75 valve switches in a similar way as the boost controller according to what the cars computer has to do to make 14.5PSI. So as far as i can tell, both the EBC and N75 essentially do the same thing. except one is controlled by the ECM. the other is controlled by the boost controller unit itself.

Since i do not have EMCS, i cannot go back to stock settings. so i want to be able to use this EBC to go anywhere from 11.6-15psi throughout the rpm range depending on how i feel i want to drive.

If i split the boost lines from the intake(turbo housing) into two, one going to the N75 and one going to the NEW solenoid for the EBC so that both can take readings on intake pressure. there will be closed hose on the other wastegate side of the N75 valve. only one hose coming off the NEW EBC solenoid that leads to the wastegate. This way I believe boost will be controlled inside the car and there should be no fault code because the N75 is still taking readings that allow it to figure out proper A/F mixtures(also job of MAF and o2). This way I can somewhat retune the car on the go.

I am looking for someone to think this over an tell me if it will work and what I might do if I am wrong.

Thankyou very much

 

Take the N75 valve out the loop and just leave it pluged in to the electrics and you will be fine there is no need to run it in the loop at all but what you will need is a remap with the new turbo or it would have been a waste of money buying the K03s in the first place.

 

ok so i will try that then
I called APR and they said because of the drive by cable system. the ko3 and ko3s work exactly the same with their software. i bought the s becuase the ko4-15 and ko3 were backorderd for 6 months and i need one now.

 

Well OK but I would have thought a K03s would yeild better power with the right map for the turbo but oh well can't be that much in it then.

 

that shouldnt be true cause i got the k03s for the same reason and the 03s makes all but 20hp that the 04-15 does...

 

Im lost, are you saying the ko3s should have 20hp more than the ko3? i dont see what your saying. were not talking about the ko4-15 at all. Im using ko3-29(s)

 

Put it this way a K03 will max out around 195bhp where as the K03s is good for around 220bhp depending on who remaps it and all the extras.
In standard form the K03 is tuned buy Audi to 150bhp and the K03s to 170bhp in the US and 180bhp in Europe plus our cars where fitted with a 4bar FPR as standard and no Smog kit so we get more power.
With the right mapping Issue no reason why you should not see around 210-215bhp as you guys have better fuel. I think the problem in the US is that you never got a A4 with a K03s turbo on a NDBW where as in Europe we did so tuners have map our cars accordingly

 

yea, the 2001's that the k03s started comming on have 170hp

just run the ebc instead of the n75

 

OK so before i installed the new turbo i was using the stock N75 with the apr chip. The "Gizzmo IBC" EBC was in my dash and functioning as a digital boost gauge with no control over boost whatsoever because the solenoid the EBC came with was left in the box until yesterday when i installed the new turbo.

-Before yesterday the EBC was reading 14-16psi as it should with the chip. So i know the gauge is accurate.
-The wastegate on the new turbo was tested to open between 10-11 psi BEFORE it was installed yesterday.
-New OEM Diverter Valve was installed along with turbo.

As we had it all apart installing the turbo, I took the 2 hoses from the N75 and removed them from the old turbo`s pressure line and wastegate actuator line and cut them shorter and plugged the ends of the hoses so there would be no leaks fromthe N75 because it is still clamped into the Turbo inlet Pipe. along with the 2 hoses being plugged, the wires that plug into the N75 valve were still connected to the ECU so it would prevent it from causing a MIL fault.

After doing that to the N75,I plugged the NEW solenoid into the EBC (which was inside the car ready to go). I did exactly as the EBC manual said to do as shown in the picture I included. (a hose the wastgate and a hose to the turbo pressure nipple)

Everything was put back together and had a successfull first start,after it reached operating temperature we took it for a drive with the duty cycle set to minimum (10%) on the EBC inside the car. when driving the new turbo i noticed a much better and smoother power but the boost would not go past 5psi. We continued to tune the EBC duty cycle between minimum boost(10%) and maximum boost(90%) with no results, the engine was not creating more than 5psi on any setting.

There are no air or coolant or oil leaks anywhere.

The N75 has no hoses which lead the turbo.

There is no MIL engine light on. it doesnt turn on when i disconnect the wires from the N75 either so i kept it connected.

If i clamp the hose from New solenoid to the wastegate I am able to create as much boost as I want (i hit 15-16 psi) but I obviously cannot drive it like that.

It continues to only produce 5 psi when i unclamped the Wastegate hose.

I was searching forums and noticed people sometimes go into LIMP mode and that is limited to 5 psi to protect the engine. from what I can understand, the N75 causes limp mode. and My car falls within that category of 5 psi. but I rule that out when remember i have nothing connected to the N75 other than its wires.

How could limp mode happen if the wastgate mechanically opens at 10-11psi. what else could cause this, if anything i should be getting too much boost rather than 5 psi.

So as of now im completly stumped and 2 fellow audi technitions cannot think of a solution either.

Anyone know what the problem could be




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the wastegate has a 5psi spring. the n75 is what makes the wg open at 10-11psi. since you no longer have the n75 controlling the boost, your turbo is just running off the wastegate and boosting only 5psi. which means you have the ebc hooked up wrong