b5 avant AFN limp mode fault finding continues

[n1co]

Hey everybody, new to the forum but very familiar with my semi-standard 97 b5 tdi wagon lol
Recently been having an issue with limp mode occurring when pulling thru 2800-3500rpm in 3rd/4th/5th or 60/70mph if I keep her at half throttle so as not to trip it...pulls like an absolute train to 4000rpm in 1st/2nd and upto the above rpm/mph then just goes dead giving a single fault code with a Snap-On diagnostics machine - MANIFOLD TEMPERATURE SENSOR, G72, intermittent
All intercooler hoses, inlet manifold, EGR and turbo (VNT15) have been removed and cleaned by myself...new coolant temp and inlet manifold temp sensor' and MAF sensor been replaced with genuine Audi parts(to reduce the risk of faulty goods) all vacuum hoses replaced with braided hoses like the standard ones and even the MAP sensor hose in the ECU box...which, by the way, was covered in oil, which I cleaned with brake cleaner...so this led me to believe the MAP sensor maybe dead, confirmed later with my pals RAC diagnostic laptop - MAP SENSOR, permanent
Still after all this there is no difference at all in how she performs so I guess my question is 'because it's an old AFN with MAP sensor soldered to the ECU board, will I now need a new ECU and have it programmed to my motor? If so does anyone have a ball park figure on how much this may cost, where in Leicester/Midlands if anywhere lol and what items on the car have to be re-coded?
Any information would be greatly appreciated!!
Thanks
Nico

[sammydfp36]

Hey everybody, new to the forum but very familiar with my semi-standard 97 b5 tdi wagon lol
Recently been having an issue with limp mode occurring when pulling thru 2800-3500rpm in 3rd/4th/5th or 60/70mph if I keep her at half throttle so as not to trip it...pulls like an absolute train to 4000rpm in 1st/2nd and upto the above rpm/mph then just goes dead giving a single fault code with a Snap-On diagnostics machine - MANIFOLD TEMPERATURE SENSOR, G72, intermittent
All intercooler hoses, inlet manifold, EGR and turbo (VNT15) have been removed and cleaned by myself...new coolant temp and inlet manifold temp sensor' and MAF sensor been replaced with genuine Audi parts(to reduce the risk of faulty goods) all vacuum hoses replaced with braided hoses like the standard ones and even the MAP sensor hose in the ECU box...which, by the way, was covered in oil, which I cleaned with brake cleaner...so this led me to believe the MAP sensor maybe dead, confirmed later with my pals RAC diagnostic laptop - MAP SENSOR, permanent
Still after all this there is no difference at all in how she performs so I guess my question is 'because it's an old AFN with MAP sensor soldered to the ECU board, will I now need a new ECU and have it programmed to my motor? If so does anyone have a ball park figure on how much this may cost, where in Leicester/Midlands if anywhere lol and what items on the car have to be re-coded?
Any information would be greatly appreciated!!
Thanks
Nico

Well for a start , "MANIFOLD TEMPERATURE SENSOR, G72, intermittent" , is to do with either a sensor being naff/ on it's way out or the connector is off or lose.

The idea of limp mode is for the ECU to terminate power to the car to protect it's self and can happen for many reasons. I was doing a test on my a4 1999 1.9 110hp on what effects various things did to sort of check for consistence of parts , one of the thing's I did was to drive the car w/o the MAF sensor's connector connected , to see if it goes into limp mode which it did and reconnecting the part took me out of limp mode - so that part is ok.

The trouble with these type of cars tho is that one tiny thing that upsets a sensor and its limp mode , i.e .. vacuum hoses got a hole in them , or a connector is broken.

You said you have checked all the pipes and confirm there ok if so I would suggest you go round checking all the sensors connectors and give them a clean with contact spray, since one in particular is throwing up on when you enter limp mode that would be a good place to start.

"Still after all this there is no difference at all in how she performs so I guess my question is 'because it's an old AFN with MAP sensor soldered to the ECU board" How long have you had this car ? The other questions you need to ask would be ; Is this a new problem ? ; How long has it been like this ?


Good luck.

[n1co]

Thanks for your time
It's crazy, had her about 5years now and I was just starting to add a few subtle upgrades then she slowly started to die...the car has 217k, f/s/h and just had all new belts, pulleys and water pump...then the problems started about 2weeks ago. I thought I had tried everything to fix it, checking connectors, wiring, hoses, MAF, MAP, turbo, n75...almost gave up on the old girl, but then in the end I gave up with the elimination process and returned everything back to standard...no k&n, no FMIC intercooler, no boost gauge and no EGR blank...and would you believe it???...she's running absolutely bang on...***??!! She's never felt so strong, she pulls all the way thru the rev range and gearbox!! 100 mile run this afternoon and not once tripped limp mode...completely bamboozled me lmao

[sammydfp36]

Thanks for your time
It's crazy, had her about 5years now and I was just starting to add a few subtle upgrades then she slowly started to die...the car has 217k, f/s/h and just had all new belts, pulleys and water pump...then the problems started about 2weeks ago. I thought I had tried everything to fix it, checking connectors, wiring, hoses, MAF, MAP, turbo, n75...almost gave up on the old girl, but then in the end I gave up with the elimination process and returned everything back to standard...no k&n, no FMIC intercooler, no boost gauge and no EGR blank...and would you believe it???...she's running absolutely bang on...***??!! She's never felt so strong, she pulls all the way thru the rev range and gearbox!! 100 mile run this afternoon and not once tripped limp mode...completely bamboozled me lmao

Glad you got it sorted out must of been one of the mods like the EGR blank I would assume you blanked the plates off but you also need to remove or "Blank" the connector too , or the system reads like there is a fault in the EGR. Failing that there is always the case of improving things worse lol.. im very familiar with that, " just one more bolt " and snap.

However that being said, it is strange for it to work one moment and not the next and since you throw a code when it DOES go into limp mode, there are question's to be raised but I guess you can ask them when it happens again.

[Gazwould]

AFN doesn't have egr software eml or related limp mode .

A 2003+ AWX AVF does have egr software eml (OGZ) , it's just an eml check light with no running problems .

[n1co]

Yeah it's a pretty old skool setup, the AFN...and true, no lights were showing on the dash, just kept tripping the turbo at 2000rpm...seems she just doesn't like to be fiddled with, she's content with no mods and so now it's making me contemplate on having her remapped or not? and maybe I should just be happy she's still alive and well again lol...thanks again for you're help and advice