I recently changed my headers since they were cracked , after i changed them ive been experiancing a slight loss of boost/ power after 4rpm i.e it stays for 1.2 bar for a while then goes back to 1.4 normal.. the car feels like its on limp mode and not pulling as strong as before...

This happens about evrey second acceleration run and not all the time

At first i thought it might be the IATs and that the car is reducing timing i datalogged the car and the iats are normal when the problem occurs.


The strange thing about that is that when the car had 2 of the headers cracked i did not experiance this problem. Even before i replaced the headers i never experianced this problem on the track lap after lap...

I took the car to the dealer to check the boost hoses and they told me its fine and nothing is wrong??

I went under the car and checked the exhaust for any leaks and there was a slight exhaust leak before the right turbine...

There was a same leak at the right turbine before i replaced the cracked headers and didnt experiance the problem!!!



What do you think could be wrong with the car??

Could it be just the slight leak before the turbine?? which i doubt

or could it be the boost and intercooler houses???

Or could it be something in the turbine acuators?? i remember there was a recall on that they can get stuck and not produce full boost...

any input would be greatly appreciated

Moe

 

Cracked headers could just be a red herring. Do you have Durametric software? Plot your boost, AFRs, etc.

b

 

What type of headers did you replace them with? are they the same at before just not cracked? I would make sure that you are 100% sealed up from the head to the turbine. If you have one turbo not boosting as efficiently as the other, the computer will see that it is having to make actuator adjustments to get to the requested boost levels.

Also you should log ignition timing numbers as well. make sure they are not dipping.

but first make sure you have 0 leaks in the exhaust manifold.

Kindest

 

Bethim , Thanks for the prompt reply , yes they are the same headers as before but brand new..

Its very strange since before when i had the cracked manifolds there was a major leak and i didnt experiance this problem...

Do you know whats the proper ignition value in the durametric?? since there are so many values to choose from?? Iats are fine and the ambient temperature is 15 degrees , I didnt experiance this loss of surge/power even at 30 degrees ambient..

 

I would perform boost pressure leak test, if you dont find any header/turbo leaks.

 

ignition angle

 

whats your mods ??

 

i'd say the best way to identify your problem is by Durametric software

 

ok first thing is switch on and off your car and listen if the vtg actuators work, they do an on off when you switch off the car if i remember correctly. Or check the fault on durametric. This would show there immediately.
Second (and more likely) check the dump valve on both vtgs. They can leak and it is not detectable by any test or diagnostic. In fact these things go even in stock cars every few ,000 kms so you might as well change them anyway, they are not very expensive, as if they ve never been changed it is very likely that they leak.
Third do a proper leak test if problem persists.

 

Also check your diverter valves for leaks.and double check all air system clamps.

 

My car has the RS Tuning 600hp kit , its been running flawlessly for 30k kilos until now

I checked and there were no fault codes present

GT-TT , Thank you for your valuable input i doubt it is the acuators then since nothing showed up in the durametric.
About the dump valves do you mean the diverter valves??

Will do , Thank you all for the valuable feedback

 

If you are losing power intermittently, you could have a leak, or your engine could be pulling boost due to a problem. Not every problem shows up as a fault code - log AFR, lambda, boost, etc. This will tell you where the problem is coming from. Something simple like a leak, plugs, dirty MAF, to something much more complicated.

- bob

 

Thanks bob
Im currently trying to resolve my problem with durametric , since it wont allow me to log more than 2 values

 

When's the last time you changed your plugs? Datalog as others have suggested.

 

Last month...