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

SEAT Altea Hot Starting Issues

Discussion in 'Volkswagen and other VAG' started by filipharvey, May 12, 2012.

  1. filipharvey
    Offline

    filipharvey Amusing Tagline

    Joined:
    Aug 4, 2006
    Messages:
    519
    Likes Received:
    0
    [May 12, 2012]
    I have here a SEAT Altea that has been to many different places to try and sort this problem, including both SEAT and VW main dealers and specialists. It even spent 3 weeks and an engineering college!

    It will start first time every time when cold. But after it has been run and left for a while, on the first turn of the key the engine turns but fails to fire.

    The original codes stored in the ECU showed P0171 [Fuel Trim Too Lean] (present and intermittent) along with P2626 [O2 Sensor Pumping Current Trim]. Both of these point to a faulty lambda or MAF reading, however these were shown to be functioning correctly under test. They have also not shown up again during the 5 days I have had the car.
    The coolant temperature sensor was then replaced as a matter of course, due to this being a regular failure of VAG models and widely attributed to the symptoms of this vehicle.

    Since that time, the vehicle has been tested on several cold to hot runs, both static and mobile.
    The starting issue arose again on a few occasions. On each of these occasions the coolant temperature was indicated to the ECU at 66°c. This seemed about right, but it just seems strange that it was the same temperature reported each time.

    During further testing, the vehicle was found to have a misfire on 2 cylinders, although this was not a fault reported to the ECU. This was shown on cylinder 1 and more predominantly on cylinder two.

    Full sensor, switch and relay diagnostics have been carried out, and appear to be working.
    The EVAP control valve has been removed, checked for leaks and retested.


    On one particular scan, the CAN network reported a break in communication to the engine ECU that hadn't shown up before. It was also noted that this fault had been reset 22 times previously.
    This fault may however not be related to the starting issues, and has not shown up when testing the car during fault conditions.

    Any ideas? Anyone?
    Last edited: May 12, 2012
    #1
  2. Ads

    Ads

    [Sep 18, 2014]

  3. Viking
    Offline

    Viking Member

    Joined:
    Mar 20, 2010
    Messages:
    219
    Likes Received:
    20
    [May 12, 2012]
    Have you changed the battery?
    #2
  4. filipharvey
    Offline

    filipharvey Amusing Tagline

    Joined:
    Aug 4, 2006
    Messages:
    519
    Likes Received:
    0
    [May 12, 2012]
    I'm not sure when the battery was last changed. I shall enquire!
    The crank seems to be strong though, and will turn over at a decent speed for as long as I dare to try when it won't start.
    #3
  5. J0N35Y
    Offline

    J0N35Y Member

    Joined:
    Mar 17, 2012
    Messages:
    67
    Likes Received:
    2
    [May 12, 2012]
    If you disconnect the temp sensor will it start straight away?? That's a sure sign the starter's on its way out!
    #4
  6. George The Diesel Head
    Offline

    George The Diesel Head Member

    Joined:
    Dec 19, 2011
    Messages:
    84
    Likes Received:
    1
    [May 12, 2012]
    This, and the starter motor.

    When the engine is hot, it has to turn over faster than a certain speed before the ECU will inject fuel.
    #5
  7. Viking
    Offline

    Viking Member

    Joined:
    Mar 20, 2010
    Messages:
    219
    Likes Received:
    20
    [May 12, 2012]
    I'm not sure if I'm being helpful here or not, as my Altea had the same problem but was a 2.0ltr TDI while I think from your post yours is a petrol? It's not an Altea specific problem.

    On mine the engine needs a minimum crank speed for the ecu to enable fuel injection. From memory the speed is 280rpm. If the battery is getting old then it doesn't hold charge as well, and when in use it drops charge slightly and can't deliver the correct engine speed. Given time to recover it can then spin the engine over fast enough for the ecu to see the correct rpm, and this isn't an engine temperature issue, more like time for the battery to recover.

    If the battery change doesn't solve it, and the engine speed is still below 280rpm when hot then the starter is probably faulty and should be replaced.

    Engine crank speed can be measured in VCDS somewhere (again, my memory fails me) and this will tell you if you're looking in the right direction.
    #6
  8. filipharvey
    Offline

    filipharvey Amusing Tagline

    Joined:
    Aug 4, 2006
    Messages:
    519
    Likes Received:
    0
    [May 13, 2012]
    That is not really something I can easily test, as it is only with the first turn of the key that it happens.
    That pointed me to immobiliser issues, but everything checks out as it should there, so I'm at a loss.

    I should point out that this isn't my car and that it has been doing this for over two years, so degrading sensors and battery don't really make any sense.
    The battery whilst obvious, doesn't seem plausible, as it will start when hot (around 70+) and also cold. Not only that, but when this happens, it is literally: turn the key off, turn it on again and it fires. If the battery wasn't strong enough on the first attempt, then it is electrically impossible for it to have more power to enable a faster crank speed on the second turn of the key, surely? - And why 66°c?

    The battery showed just under 14v whilst running, although I haven't tested it without running.
    #7
  9. J0N35Y
    Offline

    J0N35Y Member

    Joined:
    Mar 17, 2012
    Messages:
    67
    Likes Received:
    2
    [May 18, 2012]
    Trust me, try it!!
    #8
  10. filipharvey
    Offline

    filipharvey Amusing Tagline

    Joined:
    Aug 4, 2006
    Messages:
    519
    Likes Received:
    0
    [May 18, 2012]
    I can't believe that a starter motor that was on it's way out over two years ago would still work today.
    I've tested the crank speed whilst it won't start and it is around 320rpm, so I think we can discount the starter motor anyway.
    #9
  11. Viking
    Offline

    Viking Member

    Joined:
    Mar 20, 2010
    Messages:
    219
    Likes Received:
    20
    [May 19, 2012]
    Can you tell us exactly what engine this is please, and age of the car (in case I missed it).
    #10
  12. filipharvey
    Offline

    filipharvey Amusing Tagline

    Joined:
    Aug 4, 2006
    Messages:
    519
    Likes Received:
    0
    [May 23, 2012]
    Sorry, it is a 2004 Seat Altea 1.6 (BGU) - 54,000 miles.
    #11

Share This Page