Boost cutting out

[Beastly]

well I cursed myself by claiming that my car was running good in an earlier TC post this week. Ran it hard yesterday and boost was cutting out around 4.5K to 5K RPM. No CEL but pulled the following code:

17963 Charge Pressure Max Limit Exceeded
P1555-001 Upper Limit Exceeded

Note I have an APR chip but running in "stock" mode.

Needless to say 1) that is a scary code and 2) its strange that the boost was fine before the engine was pulled two times, will be talking to my dealer on Tuesday. My guess for now is that N75 or some vac line is not working right and thus the ECU is dialing back boost. I have Vag-com but wanted first to tap the BT for the right blocks to log and/or other diagnostics to preform.

Thanks in advance....

[mmaturo]

I don't know if it has anything to do with it but when my forst two TCs were going it coincided with complete cuts in boost. The explanation was that the tranny was telling the engine it was getting too much and shutting the turbos down.

[skribe]

http://images.cheezburger.com/completestore/2009/7/6/128913452931699216.jpg

NO. NOT THE TRANNY. NOT AGAIN!

[DHall1]

Same old story. Start with 3,31,115.....2nd gear pull from 3000 to redline. Report results. Then reset ecu and go out and do the same log. If overboost happens then log 114 to check the N75 duty cycle. If N75 duty cycle is ok then replace N75 and check pressure lines to wastegate.


well I cursed myself by claiming that my car was running good in an earlier TC post this week. Ran it hard yesterday and boost was cutting out around 4.5K to 5K RPM. No CEL but pulled the following code:

17963 Charge Pressure Max Limit Exceeded
P1555-001 Upper Limit Exceeded

Note I have an APR chip but running in "stock" mode.

Needless to say 1) that is a scary code and 2) its strange that the boost was fine before the engine was pulled two times, will be talking to my dealer on Tuesday. My guess for now is that N75 or some vac line is not working right and thus the ECU is dialing back boost. I have Vag-com but wanted first to tap the BT for the right blocks to log and/or other diagnostics to preform.

Thanks in advance....

[mmaturo]

I must be the luckiest on only one part with all my Audis which is that I have never had the N75 go in the RS or my two TTs. *finding wood to knock on*

[Beastly]

http://www.rs6.com/attachment.php?attachmentid=11383

[Greg@DMtechnik]

press turbo mode then you log :P looks like making too much boost over requested either vac leak or a bad n75

[JSRS6]

looks like another overboost into limp mode...order a new n75. ^^^yeah what he said. check your vacuum lines while the airbox is off. and definitely press turbo mode next time...lol.

[Beastly]

thanks for the input.

When I press the turbo button my Vag-Com says: Turbo mode not available for people who bought the cheap fleebay USB cable - ouch

[Greg@DMtechnik]

u can buy a 10.63 VAG-COM Cable these days with software its a 1:1 Real Clone for $28 if you plan on loggin the car buy that cable

[JSRS6]

^^^Veddy interesting...

[4everRS]

that is interesting. A friend of mine with an a8 tried to do that but it didnt work well. He may have downloaded the wrong software, or bought the wrong cable. It does log blocks up to 30 but not any over.

[JSRS6]

u can buy a 10.63 VAG-COM Cable these days with software its a 1:1 Real Clone for $28 if you plan on loggin the car buy that cable

You got a source?

[Beastly]

By way of closure and for the record, the problem ended up being a vac line that was not tight to the N75 thus causing the over-boost condition. As speculated it was likely due to the multiple in/outs of the eng.

Its tight and the beast is back to full boost, in all the cheapest fix. Thanks again for the input.

[speedtrapped]

glad to hear it