1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Dismiss Notice

cr140 starting problem

Conza Apr 1, 2019

  1. Conza

    Conza South East

    121
    20
    18
    Ive recently acquired a 2010 audi a3 sport cr140 with the cffb engine

    i got it cheap as the alternator pulley had fallen off and the belt went into the cambelt and it jumped 4 teeth,
    i retimed it up and it fired up and ran okay so replaced belt kit and water pump and timed it up with new alternator and belt,

    then it wouldn't start and kept getting a low fuel pressure code come up on vcds so i replaced the intank pump and filter which didn't do anything so replaced the solenoid on the top of the mechanical pump and the pressure regulator on the end of the rail and i got it to run and go etc, it smoked a bit like the dpf was blocked so did a force regen on it and was all good till i went to start it the next day, i unplugged the coolant temp sensor and it instantly fired into life but smoking again so replaced the coolant temp along with the oil and filter and air filter as noticed it was slightly over filled,

    now it wont start again till cts is unplugged even tho its brand new and have that horrible sort of blocked dpf smell from the exhaust along with the smoke,

    once its going it fine and drives lovely apart from i think the maf is packed up which i have one arriving today as its doesnt seem like it has a turbo and have had is fault code twice now.

    would a mass air flow cause my starting fault or do we reckon its the pain to change egr as that would explain the smoke etc, just cant see what would change with the temp sensor unplugged and it wont start with the maf unplugged

    many help would be appreciated
     
  2. Avatar

    snack-media
    Advertisement


  3. ScottyP45

    ScottyP45 Well-Known Member

    1,658
    70
    48
    So since you have vcds, with the engine off first, log live intake air temp and coolant temp (with all sensors connected), should be near ambient on a cold engine, also airflow actual, should be around zero, and manifold pressure which should be about 1000mb give or take a few.

    Record the values, that way you know what temperatures the car thinks it sees, and if the maf is showing a value with no air flow or is stuck at a fixed value (broken) .

    Then if it will only start with the cts unplugged, do that, start it, and log the above in addition to fuel pressure and injector fuel correction or adaptive trim. That should be between zero and +/-1 roughly for each injector, and fuel pressure at idle around 290bar.

    You might just see something. Readings are more useful than codes for something like this.

    You can also read ash mass in the Sri screen which will tell you if the dpf is plugged.
     
    Last edited: Apr 1, 2019
  4. Conza

    Conza South East

    121
    20
    18
    Think I’m gonna see if I can borrow a leak off tester from another garage that fits my injectors just to rule them out tomorrow there a few months old but where fitting by a diesel injection specialist that’s not got the best reputations so just because there new I will rule them out as the engine hunts and shakes a bit sometimes then clears then does it again and it’s really down on power, I tried a brand new Bosch maf today and it’s no different so I’ll be able to wrap that back up and give it back, just hope it’s a simple fix, really missed my old one so had to snap this up as it was so cheap
     
  5. ScottyP45

    ScottyP45 Well-Known Member

    1,658
    70
    48
    Ok hang on, new or replacement injectors need coded to the ECU using vcds or they won't work properly, the ECU will be using the long parameter string for the old injectors. You have to put the injector numbers off the top ring into the ECU and save them in the right blocks. You have to check the basics are right before anything is done or you're just ******* in the wind bud.

    See here
     
  6. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User

    7,290
    3,626
    113
    Hope you got it really cheap as it's costing you a lot in parts and you haven't got it running yet. Have you checked the compression, timing does not have to go far out for a valve to meet a piston. By disconnecting the CTS the engine will switch to a default temperature so fuelling will be different. Likely the fuelling will be richer than normal which could be why it starts. White smoke is unburnt diesel, If you have a cylinder that's not firing because of low compression that diesel will find it's way into the exhaust and you will get white smoke.
     
  7. Conza

    Conza South East

    121
    20
    18
    Not sure can’t find the invoice in the paperwork bud the codes stored match the ones on top of the injectors
     
  8. Conza

    Conza South East

    121
    20
    18
    Not really spent that much owes me £800 as it stands at the moment which included sticking 4 tyres on it, it doesn’t smoke all the time and does run Lovely just the odd time it don’t, I’ll start with the leak off tomorrow, I’ve got a mate who works in a parts place so getting everything on staff discount which helps
     
  9. ScottyP45

    ScottyP45 Well-Known Member

    1,658
    70
    48
    No worries mate, I just reckon you'd find out more about what's going on by reading the cts input, injector adaptive fuel trim, fuel rail pressure and finally airflow with vcds which will paint a picture of what's up.

    If it was me, I'd want to know that stuff to see if it's overfueling and then why.

    All of the issues could be down to one component like say, the rail pressure sensor or maf input value going to a bad level sometimes. Or a map sensor transmitting a pressure value that's higher than actual.

    Hope you get to the bottom of it.
     

Share This Page

Do Not Sell My Personal Information