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  1. #1
    Registered Member One Ring
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    Polishing a turd - An A4 Story

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    Hope this place is busier than VWVortex, man that place is dead.

    I'm going to be using this thread for a number of reasons.

    First to document my own progress on this car and use it to keep myself sane on everything that I've tried, and everything that I've done so I can go back and reference it when needed.

    Secondly, to try and help others who may be in a similar situation that I'm still in.

    Lastly, because forums are dying, and it's really sad, honestly. I've made a lot of friends on forums and I want that to continue on. I haven't been on VWVortex in years because I've been out of the VW/Audi game, but I'm back and I hope I can contribute.

    So without further adieu, here is my $500 turd.

    Audi A4
    1.8T
    Quattro
    5 Speed
    153,xxx



















    So where do we stand?

    Well, the car doesn't start, hence why I got it for $500. This is everything I know about that current situation.

    Cranks, but will not start. Brand new battery, new fuel pump relay. Previous shop said that it's getting fuel at the rail (so fuel pump is good, I'm still going to double check this). They said it wasn't the coil packs, coil pack wiring, or spark plugs. They said it "kept blowing fuses", although I'm not sure which ones. Apparently the car is not sending the "injector pulse" and hence the injectors are not sending the fuel (or so they say). I'm going to try replacing the crank shaft position sensor first and then try the cam shaft position sensor and we'll see what happens. The next possibility to me would be the wiring harness or the ECU, which leads me to my first question.

    I'm not wanting to rip this ECU out just to check the part number on it. Is there a way to check the part number for the ECU on this by using the VIN? Or would it be stamped somewhere else on the car? There are two Audi's in junkyards nearby, and one of them is an exact match to my car, same year, drivetrain, motor, and transmission, so if that won't be a match i'm not sure what is. Figured I'd snag that ECU for the cheaps if I can.

    Anyway, glad to be back. Hope you guys enjoy this thread.

    Oh yeah, the plan is to daily it through the winter providing I can get it running and then Ute conversion it from Smyth Performance in the spring. :laugh:

    Matt

    A few updates

    Update

    Fuse 29 was blown after opening the fuse box. Replaced the spark plugs and cranked again, fuse 29 blew once again. The rest of the ECU fuses remained intact and didn't have any issues.

    Only the front driver side door and rear passenger door windows are responding to the main window switch. Need to address that after I get it running.

    Update

    Another update

    When locking the car, the only door that locks is the rear passenger door. Could this be related to the no start problem, possibly there being a bad ECU?

    Update

    A small update, but a good one!

    I started reading a bit about what could cause Fuse 29 to blow consistently. I don't even have to crank it for it to blow, so it is likely something electrical. Most people were saying it was either the coil pack harness, the main wiring harness, or the ECU/ ECU relays. So I took a few steps to try and narrow it down.

    1. Unplugged all of my coils and put the key in the ignition - blown fuse. Pretty sure that narrows the coil pack wiring from being bad.
    2. Unplugged my ECU and put the key in the ignition - no blown fuse. A good sign, but it didn't rule out the wiring harness.
    3. Went to a local scrap yard, pulled an ECU (not matching part number) out of a car and walked out only paying $30. Plugged it in, put key in the ignition - no blown fuse.

    This gives me great confidence that it's the ECU unless i'm completely missing something. I ordered one on ebay with a matching part number (as a matter of fact, the date stamp is only 3 DAYS apart from each other), and it should be here sometime next week. Called a local dealership and they said they would flash it with my two keys for $175. So fingers crossed we'll be good to go after that!

    I might try and do some cleaning of the car tomorrow since I have more confidence it will run eventually.

  2. #2
    Established Member Two Rings physicsgeek's Avatar
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    Jan 29 2016
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    St. Louis, MO

    Welcome to audizine. Glad to see the ECU seems to be clearing up some issues for you. I donít know if I can be much help but I think you will get decent response here.


    Sent from my iPhone using Tapatalk
    '04 a4, 211k miles and counting, 1.8T 6speed manual, 25th anniversary interior swap, lowered suspension, and other random things...

    working without a garage is a major pain....

  3. #3
    Established Member Two Rings
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    Feb 10 2011
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    Location
    Albion, MI

    Nice looking car for 500. Welcome to audizine. I've always liked it here. Hope you do too.

    Sent from my LG-TP450 using Tapatalk
    2004 Audi A4 Quattro 3.0 6sp Ultrasport

  4. #4
    Veteran Member Four Rings jpulll's Avatar
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    Ohio

    Polishing a turd - An A4 Story

    Check the wiring behind your injector connectors. Pull back the rubber boot and see if the wiring is exposed. Fuse 29 is engine management related and I believe it pops when the coil pack or injector harnesses have wiring exposed. Also getting a fuel related code has me thinking itís your fuel harness. Spent a good day trying to figure that one out when it happened to me awhile back.


    Sent from my iPhone
    Last edited by jpulll; 10-13-2018 at 01:23 PM.
    2003 A4 1.8T 5-spd w/ Motoza 93/E85.

  5. #5
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    Quote Originally Posted by jpulll View Post
    Check the wiring behind your injector connectors. Pull back the rubber boot and see if the wiring is exposed. Fuse 29 is engine management related and I believe it pops when the coil pack or injector harnesses have wiring exposed. Also getting a fuel related code has me thinking itís your fuel harness. Spent a good day trying to figure that one out when it happened to me awhile back.


    Sent from my iPhone
    99% sure it's not a wiring issue with that. When I switched the ECU it didn't pop anymore, even with the coils plugged in.

  6. #6
    Veteran Member Four Rings jpulll's Avatar
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    Quote Originally Posted by SKYNET KC View Post
    99% sure it's not a wiring issue with that. When I switched the ECU it didn't pop anymore, even with the coils plugged in.
    Be 100% sure and pull the rubber boots back and check. These are common electrical problems that happen to the 1.8t engine, whereas, a dead ECU is a once in a blue moon electrical problem. If it makes you feel more inclined to check, my injector harness started shorting out right around the 150k mile mark. Then my coil pack harness did the same right around the 160k mile mark.

    As I tell everyone whom I help on this forum, it is good practice to check simple/cheap things before you jump to conclusions that the computer of the car went bad.


    Sent from my iPhone
    2003 A4 1.8T 5-spd w/ Motoza 93/E85.

  7. #7
    Registered Member One Ring
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    Quote Originally Posted by jpulll View Post
    Be 100% sure and pull the rubber boots back and check. These are common electrical problems that happen to the 1.8t engine, whereas, a dead ECU is a once in a blue moon electrical problem. If it makes you feel more inclined to check, my injector harness started shorting out right around the 150k mile mark. Then my coil pack harness did the same right around the 160k mile mark.

    As I tell everyone whom I help on this forum, it is good practice to check simple/cheap things before you jump to conclusions that the computer of the car went bad.


    Sent from my iPhone
    Why would it continue to pop the fuse if all the harnesses were disconnected, and then not blow a fuse when they were connected and a new ECU was plugged in?

    Iíll still check them, Iím just trying to see the logic in that it still might be the problem.

  8. #8
    Veteran Member Four Rings jonan's Avatar
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    Quote Originally Posted by SKYNET KC View Post
    Why would it continue to pop the fuse if all the harnesses were disconnected, and then not blow a fuse when they were connected and a new ECU was plugged in?

    Iíll still check them, Iím just trying to see the logic in that it still might be the problem.
    Maybe the immobilizer prevented it from shorting when you switched in a foreign? My wiring was toast at 160k...had to replace injector and coilpack harnesses...

  9. #9
    Veteran Member Four Rings jpulll's Avatar
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    Quote Originally Posted by SKYNET KC View Post
    Why would it continue to pop the fuse if all the harnesses were disconnected, and then not blow a fuse when they were connected and a new ECU was plugged in?

    Iíll still check them, Iím just trying to see the logic in that it still might be the problem.
    Youíll probably learn with this car that electricity is weird and illogical.

    I just donít want you to get the new ECU, have it programmed, and still have your issue unresolved.

    Iíve heard of stories where the ECU did die (usually from water damage), but theyíre so rare compared to bad wiring or two sensors with the same style connector plugged into the wrong harness.





    Sent from my iPhone
    2003 A4 1.8T 5-spd w/ Motoza 93/E85.

  10. #10
    Veteran Member Four Rings jpulll's Avatar
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    Quote Originally Posted by jonan View Post
    Maybe the immobilizer prevented it from shorting when you switched in a foreign?
    This is what Iím theorizing but I donít know for sure.


    Sent from my iPhone
    2003 A4 1.8T 5-spd w/ Motoza 93/E85.

  11. #11
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    Iím getting fuel at the rail. Would that rule out the injector harness? Or does it just rule out the fuel pump?

  12. #12
    Veteran Member Four Rings jonan's Avatar
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    Quote Originally Posted by SKYNET KC View Post
    Iím getting fuel at the rail. Would that rule out the injector harness? Or does it just rule out the fuel pump?
    my car was running fine with the frayed wiring...just had a random misfire here and there that got progressively worse over time, you have to physically pull back the injector boots to see if the insulation is flaking off or not...it takes like five seconds to check...
    Want my guns??? ΜΟΛΩΝ ΛΑΒΕ!!!

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  13. #13
    Senior Member Three Rings egovreau's Avatar
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    Quote Originally Posted by SKYNET KC View Post
    Iím getting fuel at the rail. Would that rule out the injector harness? Or does it just rule out the fuel pump?
    If you've verified fuel at the rail, it just means the fuel system is working.

    I don't think I saw if you removed the injector wires with the original ECU.

    I would have to look it up to verify, but I think you should have 5 VDC to one wire of each injector, then the ECU activates the control to complete the circuit, activating the circuit.

    It'll be a pain in the arse, but you might want to do a resistance check on the injector wires. Both end to end and end to ground.

    Is there any evidence of water ingress into the ECU? It's location makes it a possibility if the battery tray drains get clogged.



    Sent from my SM-G965U using Tapatalk

  14. #14
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    Think that's enough of a crack to cause no injector pulse?

  15. #15
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    I've been looking at threads of people repairing them, but not much is making sense with what they're hooking it up to. I see the actual plugs with the 6 inch leads, but i'm not sure what to do with them after that.

    Do people just cut the harness back as far as they can see damage then run new wire all the way to the actual plug?

  16. #16
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    In particular i'm confused with what is happening in this thread >>> https://www.audizine.com/forum/showt...Harness-repair

    in this picture.



    I see he came off with the new leads, but i'm confused with what they're connected to, or how they're connected.

  17. #17
    Senior Member Three Rings egovreau's Avatar
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    Quote Originally Posted by SKYNET KC View Post
    In particular i'm confused with what is happening in this thread >>> https://www.audizine.com/forum/showt...Harness-repair

    in this picture.



    I see he came off with the new leads, but i'm confused with what they're connected to, or how they're connected.
    The injector wires follow back to the ECU and are pinned into the large block connector to the ECU.

    However, what happened here and what is common is to follow the wires back to a point not on top of the engine and cut them off there, the install a 12 pin connector and rebuild the harness over the engine.

    Why 12 when there are only 8 wires, you may ask? It usually includes the three wires to the cam position sensor which is part of that section of the harness. There's a pretty good DIY that explains how to do it as well as the parts needed.

    Or, if you're feeling industrious, you can replace the entire wire harness from the injector plugs to the ECU.

    Sent from my SM-G965U using Tapatalk

  18. #18
    Senior Member Three Rings egovreau's Avatar
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    The DIY...

    https://www.audizine.com/forum/showt...or-Harness-DIY

    Sent from my SM-G965U using Tapatalk

  19. #19
    Veteran Member Four Rings Seerlah's Avatar
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    A place between here and there

    I run EV14 injectors, cut the stock wires back some, butt connected EV14 connectors on, wrapped in cloth tape...good to go!
    I hate it when my car acts like a little bitch, treating me like a bitch

  20. #20
    Veteran Member Four Rings Seerlah's Avatar
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    A place between here and there

    Old setup, but allows you to see much easier how I did mine.



    I then decided to tuck it under the intake manifold. Also shows the coil pack under the coil cover. Once on it covers how they are all lopsided, but keeps the harness for them on the cold side of the engine.

    I hate it when my car acts like a little bitch, treating me like a bitch

  21. #21
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    Quote Originally Posted by egovreau View Post
    The injector wires follow back to the ECU and are pinned into the large block connector to the ECU.

    However, what happened here and what is common is to follow the wires back to a point not on top of the engine and cut them off there, the install a 12 pin connector and rebuild the harness over the engine.

    Why 12 when there are only 8 wires, you may ask? It usually includes the three wires to the cam position sensor which is part of that section of the harness. There's a pretty good DIY that explains how to do it as well as the parts needed.

    Or, if you're feeling industrious, you can replace the entire wire harness from the injector plugs to the ECU.

    Sent from my SM-G965U using Tapatalk
    Iím not sure Iím up to the task of creating that entire harness. Iíll probably just order the new plugs with new leads and cut everything back far enough to where I donít see any cracks and tie it all together.

    I guess I just need to find the best way to connect the leads to the old part of the harness.

  22. #22
    Veteran Member Four Rings Seerlah's Avatar
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    A place between here and there

    ^Read my prior posts, with pics for reverence. May be the simplest and easiest way to go about it.
    I hate it when my car acts like a little bitch, treating me like a bitch

  23. #23
    Veteran Member Four Rings jonan's Avatar
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    Quote Originally Posted by SKYNET KC View Post
    Iím not sure Iím up to the task of creating that entire harness. Iíll probably just order the new plugs with new leads and cut everything back far enough to where I donít see any cracks and tie it all together.

    I guess I just need to find the best way to connect the leads to the old part of the harness.
    i bought four of these injector pigtails and then four of the boots to cover the wiring after they were spliced in...

    https://www.partsgeek.com/gbproducts...ad=47433965772

    https://www.ecstuning.com/b-genuine-...ch/443906102g/
    Want my guns??? ΜΟΛΩΝ ΛΑΒΕ!!!

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