Audi A2 1.4 TDI Over-boost Limp Home Mode

LallAudio

New Member
Hi All. please could someone help me with the following issue. I recently have changed the intercooler in my car inclusive of boost pressure sensor, I have put a new clutch in. I also EGR deleted the car however there was a small pipe (assuming some sort of breather pipe) that had no place on the EGR delete kit so this has been blanked off, unless someone can tell me i need to do something differently.

The above work was all completed in preparation for a ECU remap. this has been completed now, the car does feel great, I have been told the EGR has been deleted off the ECU as it has been deleted physically however aver around 80mph or hard acceleration to the floor the car goes into limp mode making it almost undriveable on the motorway or on an open stretch of road. I have to turn the ignition off and on again while its still moving to come out of limp and boost properly again.

I have checked the turbo pipes, I cannot see any leaks, I do not have any hissing of boost pressure from anywhere. Does anyone know how I can stop it from going into Limp?
 

Robin_Cox

Member
Assuming this is a 75, possibly the wastegate actuator supply tube has come off or is leaking - which gives the expected symptoms as there is no regulation of over-pressure.

 

CrispyEdd

Member
THe little pipe was the vacuum for the egr mechanism to open shut, so yes blank it off. Well worth getting samco silicon hoses and replace every vacuum pipe you can first, cheap way to elimate guessing for a tiny little hose leak you cant even see.
 

CrispyEdd

Member
Ive heard that also its sometimes possible the pressure sensor in the intercooler doesnt seal great? On the 90 bhp its up in the metal pipe acress the engine. MAybe check that tight and sat in stong.
 

audifan

A2OC Donor
So what makes you think it is over boost that is the issue? What intercooler did you use and is the MAP sensor OEM or Chinese and is it the correct one for the A2? Next would be to check all the little braided hoses for deterioration between the turbo and the N75 valve including all the joints between the braided hoses and the thin plastic tube pay attention to the end fittings and elbows as they do become porous with age.

I think it is boost pressure too low that is causing the limp mode.

Make sure the small port in the lower end of the intercooler has not been drilled out as it should be solid on the A2 and the O rings on the end caps have not blown out especially the lower end cap. Ensure the turbo air outlet pipe is correctly fitted.

As you know EGR delete is illegal as the car now does not conform to its type approval.

Have a full VCDS scan done on the car and come back with the answers to my questions and the scan result.
 

LallAudio

New Member
So what makes you think it is over boost that is the issue? What intercooler did you use and is the MAP sensor OEM or Chinese and is it the correct one for the A2? Next would be to check all the little braided hoses for deterioration between the turbo and the N75 valve including all the joints between the braided hoses and the thin plastic tube pay attention to the end fittings and elbows as they do become porous with age.

I think it is boost pressure too low that is causing the limp mode.

Make sure the small port in the lower end of the intercooler has not been drilled out as it should be solid on the A2 and the O rings on the end caps have not blown out especially the lower end cap. Ensure the turbo air outlet pipe is correctly fitted.

As you know EGR delete is illegal as the car now does not conform to its type approval.

Have a full VCDS scan done on the car and come back with the answers to my questions and the scan result.
I appreciate the time taken for this reply. let me try to answer as many of these questions as I can. Firstly the intercooler I believe is a good quality part is Mhale (INTERCOOLER MAHLE ORIGINAL CI 72 000S) which I believe is the correct one for the car. However when i received this the MAP sensor removed from the old intercooler did not fit this new one as despite the body and the connector being the same the nipple that sits into the intercooler was larger on the original and the hole was smaller on the new intercooler. I then purchased a new MAP Sensor from GSF (again a good replacement part) using the reg and vin and this MAP sensor fitted in fine as it had the smaller nipple. regarding the end caps its a new intercooler i believe it was identical in every way apart from where the MAP sensor is housed. Regarding the EGR and it being Illegal I'm well aware of that and does not concern me in the slightest, as far as I'm concerned this being deleted will keep the car healthier not recirculating crap. I was told by the tuner that there were no fault codes coming up on the car so i am unsure. I have a diagnostic system i have just invested in so I will plug that in at the weekend and see if that brings anything up however it is not VCDS. if anyone can help me with the diagnosis I am happy to bring it anywhere to someone that actually knows these cars.
 

CrispyEdd

Member
I appreciate the time taken for this reply. let me try to answer as many of these questions as I can. Firstly the intercooler I believe is a good quality part is Mhale (INTERCOOLER MAHLE ORIGINAL CI 72 000S) which I believe is the correct one for the car. However when i received this the MAP sensor removed from the old intercooler did not fit this new one as despite the body and the connector being the same the nipple that sits into the intercooler was larger on the original and the hole was smaller on the new intercooler. I then purchased a new MAP Sensor from GSF (again a good replacement part) using the reg and vin and this MAP sensor fitted in fine as it had the smaller nipple. regarding the end caps its a new intercooler i believe it was identical in every way apart from where the MAP sensor is housed. Regarding the EGR and it being Illegal I'm well aware of that and does not concern me in the slightest, as far as I'm concerned this being deleted will keep the car healthier not recirculating crap. I was told by the tuner that there were no fault codes coming up on the car so i am unsure. I have a diagnostic system i have just invested in so I will plug that in at the weekend and see if that brings anything up however it is not VCDS. if anyone can help me with the diagnosis I am happy to bring it anywhere to someone that actually knows these cars.
There is a map of free vcds sercice from kind memebers on here in help section I believe
 

steve_c

Grumpy OAP & A2OC Donor
There is a map of free vcds sercice from kind memebers on here in help section I believe

Found here:
 

Andrew

A2OC Donor
location 04 @Andrew Oxfordshire is closest to me unless there is anyone closer to Aylesbury
Good Evening,

More than happy to scan your A2.

Please have zero expectation of any extra wisdom if you visit, I have never owned a diesel and never even driven one in my life!

Send me a PM if you wish to arrange a visit.

Andy
 

RAB

Technical Specialist 1.2 TDI
Regarding the EGR and it being Illegal I'm well aware of that and does not concern me in the slightest, as far as I'm concerned this being deleted will keep the car healthier not recirculating crap.



RAB
 
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LallAudio

New Member
Good Evening,

More than happy to scan your A2.

Please have zero expectation of any extra wisdom if you visit, I have never owned a diesel and never even driven one in my life!

Send me a PM if you wish to arrange a visit.

Andy
Thanks Andy, I will send you a message.
 
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