B5 s4 limp mode but at 10 psi

[andybnwc]

Ok got a problem sick of it here how it goes the car has full samco pipework which stopped a 5psi limp mode because of F hose , new n75 and everyother senser in the boost intake system, i was running dual piston blow offs but now back to 710s its intermitent and used to boost to 20psi when spiked its on a giac chip and has de-cat full stainless system bmc induction also.

Done a pressure leak test with no results im getting sick of it now and feel like smashing it up !!!

Someone please throw some ideas my way thanks

 

[shineydave]

20psi is a lot of boost for KO3's, have you tried logging the boost actual against requested? how do you know you're producing the pressures you're reporting?

i'm not an expert but it sounds like it's overboosting and going into limp mode, is the N75 piped correctly? i'm wondering if you have a stuck wastegate also.

thought for a minute it could be a blocked cat, the S4 system should monitor for such an occurence as per the self study guide in the sticky at the top of the forum and drop into limp mode.

have you got access to Vag-Com?

 

[s4mark]

my s4 was going into limp mode intermittently. Turns out it was an EGT Sensor telling the ECU that the exhaust gas tempetature was 1300. The ECU was then running low boost until the sensor gave the correct reading again.

 

[andybnwc]

20psi is a lot of boost for KO3's, have you tried logging the boost actual against requested? how do you know you're producing the pressures you're reporting?

i'm not an expert but it sounds like it's overboosting and going into limp mode, is the N75 piped correctly? i'm wondering if you have a stuck wastegate also.

thought for a minute it could be a blocked cat, the S4 system should monitor for such an occurence as per the self study guide in the sticky at the top of the forum and drop into limp mode.

have you got access to Vag-Com?

Yeh not too sure about the n75 but tried it both ways , boost guage gives me the reading it rarely goes to 20psi just a spike everyso often

gonna have to vag com it again must of spent about £400 on vag com last time i ended up finding the problem myself F-hose after spending £100s at specialists and audi them selves lol

 

[andybnwc]

my s4 was going into limp mode intermittently. Turns out it was an EGT Sensor telling the ECU that the exhaust gas tempetature was 1300. The ECU was then running low boost until the sensor gave the correct reading again.

Yeh i had that fault too replaced one so maybe the others gone cause come to think of it itwas about 10psi last time .

one other thing should the fan be on all the time?

 

[shineydave]

i think the fan should be on at low speed if the aircon is on. might be worth posting your general location, you could be close to a member with Vag-Com who'd scan it for some beer money

 

[andybnwc]

Got my location up now im in lancaster, lancashire

 

[shineydave]

Have a look here, there maybe someone on the map who can help you

http://www.frappr.com/vagcomuk/map

failing that pop over to RS246.com and pm grizz, he has a garage somewhere near there and has plenty of experience with S4's, really nice bloke. tell him shineydave sent you