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Idles, revs.....won't drive

Discussion in 'T3 & T4 Tech Help Clinic' started by Dapom, Dec 15, 2015.

  1. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Hey all :)
    Well after the last breakdown/tow home combo I modified my roller door so I could finally get the bus into the garage for some works :)
    When it broke down the bus just bus died at 100kph. Restarted and got a few hundred metres down the road a couple of times then nothing. At the time he smelt of petrol, and just prior to dying, it was driving like it was flooding...as in easing off the pedal then increasing very slowly was the only way to gain speed. When it got off the tilt tray 3hrs later it started fine and drive fine....which implied that it could've flooded and that fuel drying out over the 3hrs allowed it to clear and run.
    As I hadn't been right through the fuel system so didn't really know where I stood I did the following.
    Replaced all rubber lines from tank right round to fuel pressure reg.
    cleaned out hard plastic lines
    Cleaned out steel lines
    Had injectors prof cleaned and checked, new seals (old were wrong size and didn't seat. Injectors were FILTHY!)
    Cleaned and checked aux air valve, repaired rubber elbow, replaced hose
    Cleaned and checked csv
    Sealed hose connectors to 's' boot
    Finally, cleaned the spark plugs....more as a diagnostic tool than anything. These were BLACK! Time before that I did them they were slightly black on all bar cyl 1 and that was after 1200k's trouble free.
    Sooooo just started it up and it idles beautifully. Revs fine and sounds good. Doesn't have the power to drive down the road :-/
    Have checked afm settings as per tutorial on iterant aircooled and according to that the mixture is fine.
    I am going back out shortly as remembered I haven't cleaned the earth strap at the trans but all others are done and all wires in engine bay have been checked for shorts, loose connections etc.
    sorry this got so long winded lol
    Any ideas appreciated :)
     
  2. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    It is obviously running rich. I too have a rich running problem that I thought had been solved by replacing AFM, mine is a 2.1 MV with fresh top end rebuild. Replaced injectors, o2 sensor plugs leads cap fuel pressure reg, exchanged idle control unit with known good one but until engine reaches operating temp it runs like only 2 or 3 cylinders, at operating temp runs good. Plan to replace the ECU with known good one tomorrow. have a suspicion the throttle position switch is faulty as Nils adjusted and it ran better but now dosnt click when moved from idle position. have a new hall sender type TPS coming from vancafe. Would anyone know if faulty TPS would cause rich running. My plugs are black and sooty.
     
  3. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Mines the 2.0 a/c so no O2 sensor...(correct me if I'm wrong!!)
    I reckon it would be running rich as I have found and solved more vacuum leaks than I thought possible and, judging by examples on the vehicle of works by a so called specialist garage, I reckon mixture will have been richened to compensate.
    Is it possible to rent a gas analyser anywhere to check exhaust?
     
  4. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    no need to check my exhaust as it smells of fuel and where it blows onto the mud flap its black and sooty
     
  5. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Lol yeah mine too...I was thinking more along the lines of setting the mixture a little more precisely than the tutorial. Really don't want to have to pay someone to fix it lol
     
  6. cbus

    cbus Well-Known Member

    Messages:
    13,570
    Location:
    sunshine coast
    havent mucked with one, but fuel line pressure control do-hickey?
     
  7. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    You mean the fuel pressure regulator, I have a new one fitted.
     
  8. Kai

    Kai Well-Known Member

    Messages:
    4,794
    Location:
    Sydney, NSW
    Try your ignition coil
     
  9. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    Have been considering swapping that out to see what happens as well. Apart from using lots of oil the van was running great prior to the rebuild which is so frustrating.
     
  10. syncro

    syncro Well-Known Member

    Messages:
    10,368
    Location:
    Southern Highlands
    Have you checked your T2 temp sensor?
     
  11. AC-T3

    AC-T3 Well-Known Member

    Messages:
    1,135
    Location:
    Woy Woy
    Assuming electrics, timing and dizzy vacuum advance all OK, test fuel pressure at T junction in fuel rail at 3 - 4. If below spec pull fuel pressure regulator for a cracked or leaking diaphragm will suck raw fuel straight into the intake plenum.
     
  12. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    T2 sensor is new German
    Fuel pressure reg is new
     
  13. AC-T3

    AC-T3 Well-Known Member

    Messages:
    1,135
    Location:
    Woy Woy
    Sorry Phil, this thread is running 2 diagnostics - I'm referring to the L-Jet setup and Dapom's problem
     
  14. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Thanks ac t3 and syncro :) both good ideas. Now that I'm over my crushing disappointment of not having it fixed yesterday I'll go and have a look :)
    I plan on rechecking timing too....slim but possible chance I suppose that by fixing all the air leaks vacuum has increased thereby throwing the advance off.
    And.....I will grab another coil and see if that does it. Soooo many people have said it that I've gotta know one way or another (though I'm very skeptical bahaha)
    Onwards........
     
  15. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    7,076
    Location:
    Gosford
    I think I fixed my problem with rough idle which is worse when cold and super rich, changed the ECU and bingo runs and idles great, I noticed that the connector clicks when correctly in place so switched back to the old ecu and paid attention to the connector being fully engaged and bingo idles nice and dosnt appear to be running rich now, will see in the morning how it goes but here is hoping.
     
    hairyman, Dapom, syncro and 1 other person like this.
  16. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Have now cleaned transmission earth strap, found a couple of FI earths on a connector by #3 cylinder under inlet. cleaned that (don't try and remove to clean...it's not a good experience) one cable had a break in the pvc but copper was all good so heat shrunk that and fitted new connector.
    Tested the 'thermo time switch' for the csv and all good.
    Tested the cylinder head temp sensor and the ohm reading was nowhere near spec. Going hunting for one tomoz :)
     
  17. cbus

    cbus Well-Known Member

    Messages:
    13,570
    Location:
    sunshine coast
    Side issue and not suspect in your issue.
    if you have old woven wire earth straps that are intact but have some corrosion, replace them.
    Even though they appear sound they can have high resistance under load. Have seen that quite often.
     
  18. Syncro27

    Syncro27 Well-Known Member

    Messages:
    6,650
    Location:
    Terrigal, NSW Central Coast
    I agree Col completely.

    Mine did the same thing and made the van run horrible after warming up to only barely operating temp.

    I added a new battery cable as an earth and and instant very cheap fix. That earth helps relay all the signals and hence with some heat the resistance becomes too great causing failure or poor running issues.
     
  19. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Thanks guys. Adding big ass cable and eyes to the shopping list :)
     
  20. Dapom

    Dapom Well-Known Member

    Messages:
    805
    Location:
    Brisbane
    Question. My temp II sensor reads between 1850-1970 ohms. All the info I can find says it should read 2500 ohms at 68deg f. It was 78deg f (26c) in my garage when tested. My question is...would the higher than spec temp cause ohms to go up or down? I don't fully 'get' how this works so someone explain please :)
    If the sensor is dodgy and so telling ecu engine is colder than it is that would cause rich running....right? If that is the case would removing the spacer between sensor and block fix it? It can't be that easy surely ;) this theory comes from reading ratwells page. It says that the spacer was added by vw to make the sensor run cooler.
    Any input valued :)
     

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