Poorly Mk4 APK

Discussion in '8-valve' started by EZ_Pete, Mar 29, 2019.

  1. EZ_Pete

    EZ_Pete Forum Junkie

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    HI Folks, it's been a while.
    Trying to help a workmate with a T-reg 1999 Mk4 Golf, APK engine. Misfiring fairly horribly from a cold start and stinking of fuel.
    Got these codes out of it yesterday:

    Address 01: Engine Labels: Redir Fail!
    Controller: 06A 906 018 EF
    Component: 2.0l R4/2V MOTR HS V04
    Coding: 00031
    Shop #: WSC 00028
    VCID: 6AA7EF060567
    4 Faults Found:
    16725 - Camshaft Position Sensor (G40): Implausible Signal
    P0341 - 35-00 - -
    16556 - Fuel Trim; Bank 1: System Too Rich
    P0172 - 35-00 - -
    16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal
    P0116 - 35-10 - - - Intermittent
    16518 - Oxygen (Lambda) Sensor B1 S1: No Activity
    P0134 - 35-00 - -
    Readiness: 0010 0001


    I happen to have a spare ECT sensor so I'm going to check with measuring blocks what the present one is telling the ECU from cold, check the wiring as best as I can, then swap in the spare unless I find a wiring problem.

    He's going to buy 4 Beru spark plugs for me to fit, if I can, at lunchtime. Access looks pretty horrible for cyls 2 & 3 but I've got a flexi 3/8 extension that might help, if I can get the leads off. He doesn't know when they might have last been looked at...

    Wondering whether the cam sensor could be involved in the misfire if plugs and/or HT leads don't solve it?
    Not even sure where that is on this engine? Anything I can do to check this with measuring blocks or VC-scope? Once I find it I can check the wiring I guess.

    Precat O2 probably has had it, but might it be wiring with that fault code? Or would there be a more specific fault code for a supply/connectivity fault?

    Any experience or help with this engine would be smashing, as it's all new to me. Any questions, ask away.
    :)

    Cheers,

    Pete
     
  2. rubjonny

    rubjonny Administrator Admin

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    do all of the codes come back once cleared? some of them could be old. Check lambda wiring as you say, runs under the car on these so potential for it to be damaged
     
  3. EZ_Pete

    EZ_Pete Forum Junkie

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    Thanks for replying John.

    Cleared them all before doing anything, and none came back instantly with just ignition on. Didn't think to start it up again at that point.

    Coolant sensor was telling the ECU the engine was at 27°C which was very believable; he's just gone for a little test drive in it so I'll try to check it again when he gets back. So didn't change that, yet.

    All the HT leads seemed undamaged and all read a (similar) few kOhms so they've gone back on. Sparks were a struggle with inlet in place but got there in the end, after over an hour's battling. Old plugs were very sooty indeed.

    Running a hell of a lot smoother on new plugs, and not smelling very much at all.

    Only code that came back within seconds of startup was the cam sensor one, and I found that, not hiding too far away from the cam. :o
    Might be the next thing to have a go at next week. Looks likely to be a much easier change than the lambda...
     
  4. rubjonny

    rubjonny Administrator Admin

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    ok sounds like you may be onto a winner there, keep an eye on it as you say. if cam sensor code persists check the wiring to it, worth double checking the timing is all good too
     
  5. EZ_Pete

    EZ_Pete Forum Junkie

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    The 5V was there and the ground was OK on the cam sensor, didn't check the signal cos I wasn't really sure how to, but sort of bargained on 'if two wires are OK the third might well be too'. Not sure if he'll bother doing much more or just sell it quick while it's running sweeeeet.
     
  6. EZ_Pete

    EZ_Pete Forum Junkie

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    Well that didn't last long...:(
    I'd told him on Friday that I didn't feel we'd really addressed the source of the trouble, and that the plugs would soot up again before long. Didn't last the weekend though!

    He'll bring it back in tomorrow, so I'll have another look at what faults codes are now showing, swap out the temp sensor anyway, and have a look at cam sensor and lambda wiring. Not too sure whether the cam sensor 'implausible signal' can cause this trouble - because I'm not sure what the cam sensor controls on this engine/ECU.
    A youtube video I found seemed to suggest that the cam sprocket has to come off to change out the cam sensor, does that sound right? Not had the upper cambelt cover off yet for a look; hoping to find lots of debris that just needs cleaning out. What are the chances...? :lol:
     
  7. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    For a MK4, the CLT on them do fail on the ECT side and on the gauge (G2).

    This will cause the engine to see up to -48 deg C and wind up the lambda controller to beyond the diagnostic clip of 25% and trigger a rich running fault.
    The addition of fuel beyond what it should be for the air density at +20C will cause the engine to rich misfire.
    The front lambda sensor fault suggests a faulty sensor as a result of age and the above problem.

    G40 sensor failure, will have an effect on spark timing, sequential operation of injection windows and knock control.
     
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  8. EZ_Pete

    EZ_Pete Forum Junkie

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    Thanks, so cam sensor not very likely to be the main problem. Very helpful, ta.
     
  9. EZ_Pete

    EZ_Pete Forum Junkie

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    This car has a K'n'N type air filter. Is it worth me looking at MAF numbers with VCDS while I'm on the case today?
    Wondering if the MAF can over-read if it's mucky, and result in over-fuelling, or do they tend to under-read in that situation (seems intuitively more likely to my brain)?
    What would be a normal range for idle running?
     
  10. EZ_Pete

    EZ_Pete Forum Junkie

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    Well it had regained both the temp sensor fault code and the lambda one, so the temperature sensor got replaced. Seemed to give believable numbers on VCDS and on the gauge as the car warmed up. No missing in the few minutes I ran it. Couldn't spare the time to check lambda wiring today.
    MAF was registering about 4.7g/s cold (at idle), dropping to about 4.2 when up to temperature. Is that reasonable?
     
  11. rubjonny

    rubjonny Administrator Admin

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    ElsaWIN says between 2 and 5 g/s so looks fine, though to confirm be nice to have a logged run to see what its reading under load. you can also check lambda measuring blocks to see if its now reading better after the new temp sensor.

    or see if he is happy enough with the way it drives to not bother you any more :lol:
     
  12. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Yes, that sounds about right.
     
  13. EZ_Pete

    EZ_Pete Forum Junkie

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    Update: New coolant temp sensor, new thermostat and new front lambda sensor and it almost passed MOT today.
    Emissions were comfortably within limits, which was better than I expected. Cam sensor fault remains as the only one on an engine module scan.

    Just the rear wishbone bushes both sides as major fail items. Slightly odd 'cos the last place that failed it on emissions didn't even mention those IIRC.
    I expect I'll be sorting those out for him shortly.

    Thanks again for the inputs/help. :)
     
  14. EZ_Pete

    EZ_Pete Forum Junkie

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    We fitted new wishbones on Saturday, then it went in for retest Tuesday. Car now has an MOT. :thumbup:
    Unfortunately it's also handling like a POS apparently. Think the ball-joint to wishbone bolts need loosening off and the BJs pulling out as far as they'll go within the slots of the 'bones. Being used to the Mk1 Fabia/Polo 9N platform with no adjustment there, I just bolted them on as delivered. [:$]
     

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