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Cylinder 2 not firing

Discussion in 'A4/S4 forum(B5 Chassis)' started by B5NUT, Jun 10, 2010.

  1. B5NUT
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    B5NUT Well-Known Member

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    Today my A4 developed a fault which have to say has stupped me for the moment. The car is a 1996 A4 with a 1.8T AEB engine. I'll go through the steps that I've already done.

    • First tried a new coil pack in each cylinder
    • Second Tried a new set of spark plugs (currently running Bosch, tried NGK) no difference
    • Disconnected the plug going into each coil pack until the faulty cylinder was found.
    • After disconnecting each plug one at a time to each oil pack, 1, 3 and 4 caused the engine to start the stop after a few seconds
    • Disconnecting the plug on cylinder 2 made no difference
    • Tried the new coil pack again on 2 made no difference
    • Swapped coil packs on 2 & 3 around fault stayed with cylinder 2
    • Check with VAG-COM 10.4 beta and no faults codes were showing on the engine
    • There are no grinding, banging or rattling noises, so I don't think the piston/valves are at fault
    • Oil is a nice golden colour, there is no water in the oil or vice versa, so don't think it's head gasket.
    After leaving the engine for a while the car did start normally, and was running nice and smooth until the temp got to around 70 then cylinder 2 stopped again.


    What I want to try the following but now sure how.

    • Want to try and see if there is power going to plug 2, but don't want to fry:scared2:
    • Could this be an injector problem how can I test for this, without setting the car on fire!
    Last edited: Jun 10, 2010
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  2. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    It will be the ignition amp on top of the airbox going faulty when the car warms up
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  3. B5NUT
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    B5NUT Well-Known Member

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    Last edited: Jun 10, 2010
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  4. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Thats him, for a reason i don't know cyl 2 is the first to drop when the ICM goes bad. £30 is a bargain mate..
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  5. B5NUT
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    B5NUT Well-Known Member

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    Ok, update just did the test they showed, and I get an Ohms reading on pins 1, 3 & 4 of 5.20 on pin 2 I get nothing, 0, zip..... So I've just got to wait for the new module to arive.

    I had visions of stripping the fuel system down tomorrow, thanks for the info Mark.
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Presumably the IGBT for cyl 2 is positioned in a vulnerable position inside the IC package, probably runs hotter than the other three, so tends to wear out first.

    I concur with marks diagnosis. If you were feeling brave, you could probably move the pins around on the plugs for the driver, and see if the problem moves, but its likely less hassle to simply swap out the driver.
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  7. B5NUT
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    B5NUT Well-Known Member

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    I've got the vw tool to move the pins around on the plugs, however the ohms test was in my eyes 100% conclusive that the module is fecked. It's also a nice easy fix compared to all the mucking around I've done over the last few hours and was thinking of doing tomorrow.
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  8. stub
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    stub the matrix is comin

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    just incase it still don't work.(fingers crossed it does for you) i had the same sounding trouble a couple of yrs ago and it turned out to be the firing module. it is rare it going as its a bosh unit. and it cost me £180 inc vat.
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  9. B5NUT
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    B5NUT Well-Known Member

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    What do you mean by the firing module, The only things I can think of that controls the plugs is the ECU, ICM & coil packs. I'm 99.9999999% sure it's the ignition control module (ICM)
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    I think he is talking about the same thing.

    The module is just 4 large power transistors. Instead of the ECU having to handle the large currents required to fire the coils, the ECU just sends a small logic level signal to the ICM, and the ICM handles the big currents involved in charging and firing the coils.

    On later cars (B6's etc) they combined the coil and the power transistor into one unit, and did away with the ICM, so the ECU signals the coil directly, but still only with a small logic signal, and now the coil has its own transistor which handles the charging and firing.
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  11. NATE6874
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    NATE6874 Member

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    sounds the same as the problem I had a few weeks back. I.C.M I got one new from Euro Car Parts... £67 next day delivery I think. fitted in 5 mins, car runs sweet now.
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  12. B5NUT
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    B5NUT Well-Known Member

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    Got the part today, genuine Audi module for £30 even came with the transfer paste, will fit the part tonight and update the thread.
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  13. B5NUT
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    B5NUT Well-Known Member

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    Fitted the new ICM this evening, and the car's now running sweet again:yahoo: Thanks to all that help :beerchug:
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