Page 1 of 4 1234 LastLast
Results 1 to 10 of 32
  1. #1
    Join Date
    Feb 2017
    Posts
    103

    Exclamation no spark still, please help

    This is a repost of an issue I was having last week, but I've been testing everything and I really need some expertise here.

    I finished rebuilding my 2007 XC70, I got her with a broken valve, tore her down and put her back together. She ran like a rock star for the first day but I started losing voltage, I replaced the
    battery, the voltage regulator, and finally bought a new alternator altogether.

    That issue is resolved but now my #2 cylinder won't fire. I've switched coil packs, the plug, nothing. If switch the connectors between #1 and #2 both plugs out, she'll keep running on 3 cylinders while I can test for spark, I get spark on whatever coil pack the #1 connector is connected to and no spark to whichever the #2 connector is connected to. This test rules out the coil pack and the plug. I replaced the connector, no difference. I tested the terminals at the connector, the ground, is grounded, the green stripe is at +12, the brown wire I assume is a ground wire or a low voltage signal that the computer sends to the coil pack to tell it when to fire. I don't know for sure, I can't figure out what it should read but it's all over the place on the voltmeter so I think I've got it understood. I traced this wire all the way back to the computer and cut it and spliced in a new wire, no dice.

    So now I think it's the computer itself. All the wires on this car are brittle and easily will fault. Once I get her running perfectly, I will replace all the coil pack connectors.

    But my thinking now is that the issues is either with the ECU or could be resolved if I just reseat (not reset, but take it out, clean the connectors and replace it) the ECU; I could easily see that connection rusted. Today I pulled off the cover and the sides off the ECU housing and pushed all 4 of the little purple rails all the way forward, as far as they would go, anyway. But the ECU's won't budge, I'm either doing it wrong or they are rusted in place.

    Am I chasing a red herring? I redid the timing in case that was it, and it was off a little (less than a tooth), but I redid it anyway and now it's perfect. In fact, the car runs remarkably well on just the 4 cylinders. But I've got to get to the bottom of this.

    Any suggestions, tips, debugging ideas, anything? It's a sweet car, clean and when she was running, she ran like a champ with acceleration and power I've never experienced with a Volvo so I cant' give up. I can't see how it could be the timing since a) there are no errors thrown and b) she runs pretty much fine on 4 cylinders, just low power and not a smooth ride.

    Finally, I tested the compression for #2 and she's sucking 140 PSI, I didn't check the rest but that seems fine to me. But that's actually irrelevant. no spark is no spark.

    Please please help, any suggestions at all, will be appreciated,

    drGian
    current lineup: 2001 Volvo v70 2.4 Turbo, 2014 Ford Flex AWD, 3.5 V6 Turbo, 2017 F-150 3.5 V6 Turbo

  2. #2
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    511

    Default

    I don't remember from your earlier threads, but it sounds like this 2007 was new to you when you got it with the broken valve? In other words, you haven't been driving it for years and thousands of miles with no problems and then one day the engine broke a valve and now you have no spark to #2 cylinder.

    Maybe this electrical problem was an issue for the previous owner too? They couldn't figure it out and they passed it on to you along with the broken valve? I guess you could contact them and find out.

    I do basic maintenance and repairs to my 07XC but your knowledge and skills are beyond anything I've done working on my car so I'm not gonna be able to provide much technical expertise. It sounds like you're taking the right approach to solving the lack of spark and maybe it does have something to do with the ECU. Have you done research with ECU problems and if they can result in missing electrical signals? Is their a special tool used to remove the ECU?
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  3. #3
    Join Date
    Sep 2002
    Location
    Belgium
    Posts
    2,388

    Default

    There is a special tool to (un)seat the ECU: https://www.youtube.com/watch?v=8iWbNCf6SoQ
    You have measured 12V on the low voltage side of the #2 cylinder coil pack?
    144 GL (1974)--->244 GL (1982)--->940 GLE 2.3i (1992)--->XC70 2.5T (2004)--->XC90 T5 (2018)

  4. #4
    Join Date
    Feb 2017
    Posts
    103

    Default

    I bought this car from a guy who's mechanic had given up on it. It ran but had no power and shook like hell. After the basic tests I checked compression and found #3 was a zero. So I tore down the engine and rebuilt it. Initially it ran amazingly on a battery with a fresh charge. But quickly it started running like crap again and I tracked that down to lower and lower voltage. I replaced the alternator and now I'm running at 14V consistently. However, my #2 won't spark and I've tried everything. I saw I guy on youtube remove the ECU's by just pushing the little purple plastic strips back and they came right out. I have pushed my little purple strips back and the ECU's won't come out.

    So that's where I'm at.
    current lineup: 2001 Volvo v70 2.4 Turbo, 2014 Ford Flex AWD, 3.5 V6 Turbo, 2017 F-150 3.5 V6 Turbo

  5. #5
    Join Date
    Feb 2017
    Posts
    103

    Default

    Thanks, I saw a guy on you tube do it with a screwdriver, but I was unable to reproduce his result. As for the 12V, I should be more clear on that. Into my 5 coils packs run 3 wires, a ground (which is grounded right there to the head) a yellow wire with a red stripe which seems to always have positive voltage while she's running, and a third wire which is a different color for each cylinder and for my #2 is brown with no stripe and I have successfully traced back to the input to the ECU. I didn't measure 12V on the yellow wire with the red stripe, but at one point it arced against the head and blew a fuse (labeled coil packs) so I assumed it was always hot and further assumed it was at 12V, I didn't actually measure it.

    So I don't actually know how the coil packs work. I suspect, there is constant high end feed coming from the yellow wire and then the colored wires are grounded by the computer at the appropriate time, but I don't actually know. What I do know is that the behavior of the ground and yellow wires on all 5 of my cylinders are the same, but I can't figure out how or what to measure on the colored wires (brown in the case of #2). Most of the wires that run to the connectors are cracked and the exposed copper is green with oxidation. So my theory now is that the connection between that little brown wire and the ECU is bad and just removing and replacing it (maybe cleaning the connectors somehow) would solve it.

    Can you let me know if that's a plan that makes sense, and can you explain to me the inputs to the coil pack, what they should read and how it works? I'd love that.

    Thanks,

    drGian
    current lineup: 2001 Volvo v70 2.4 Turbo, 2014 Ford Flex AWD, 3.5 V6 Turbo, 2017 F-150 3.5 V6 Turbo

  6. #6
    Join Date
    Feb 2017
    Posts
    103

    Default

    I should add that when I tore her down I found a broken intake valve on #3, I took the head to a local guy who did it up right.
    current lineup: 2001 Volvo v70 2.4 Turbo, 2014 Ford Flex AWD, 3.5 V6 Turbo, 2017 F-150 3.5 V6 Turbo

  7. #7
    Join Date
    Jul 2012
    Location
    Landenberg, PA
    Posts
    213

    Default

    Can't help you, but I admire your tenacity! Seriously.


    2005 XC70 - 50/35 Tint, Yakima Rack

  8. #8
    Join Date
    Sep 2002
    Location
    Belgium
    Posts
    2,388

    Default

    You can find Volvo wiring drawings here:
    https://qclt.com/html/volvo_ewd_us_eng/
    Go to "Group 23 Fuel systemEngine management system" to find the wiring for the coils/spark plugs.
    The designations of the figures are listed in the last section "List of components"
    144 GL (1974)--->244 GL (1982)--->940 GLE 2.3i (1992)--->XC70 2.5T (2004)--->XC90 T5 (2018)

  9. #9
    Join Date
    Aug 2017
    Location
    Pleasanton CA USA
    Posts
    386

    Default

    As far as the coil pack electronics, each pack is a 3-wire device:
    • 12V (powers the charging circuit to recharge the coil between firings)
    • firing signal - delivers the precision-timed pulse
    • Ground...completes the charging and firing circuits back to the battery

    It's easy to test for a discontinuity in the 12V and Ground at the coil harness plug. I'm not sure how to test the firing signal unless you have a scope. You might catch the pulse with a voltmeter (e.g. Fluke) that has a Max. Voltage (sample and hold) mode.

    Since you can see multiple cracks in the coil-pack wire sheathing and corrosion of the copper wire, why not just order a brand new coil-pack harness assy.?
    Start by getting a Volvo part number off the original harness. Then search Volvo and Denso for the harness.
    Last edited by pbierre; 11-06-2019 at 05:59 PM.
    2013 XC70 T6 Flamenco Red (hers)
    2015 XC70 T6 Seashell Metallic (his)
    past: 13 Volvos going back to '74 242 sedan

  10. #10
    Join Date
    Feb 2017
    Posts
    103

    Default

    Thanks for all the feedback. After all sort of debugging and determining the plug isn't the issue, the coil pack is fine, replacing the connector, jumping all the wires with new wires I've determined the only possible culprit is the ECU. Tonight I redid the timing with EXACT precision and took her for a test drive. If I didn't know I had a non firing cylinder I don't think I'd even know anything was wrong. I have no CEL, she runs pretty smooth. If I had never had her working perfectly and felt that acceleration when all 5 were firing I'd think there was no issue. But I've felt her when she was running on all five and she had all kinds of pickup and speed and torque at all RPM's. This issue showed up after the failure and replacement of the alternator. Replacing the alternator involved me removing the intake manifold and moving a log of stuff around and also, before it failed a lot of fluctuation of the system voltage.

    Today I removed both ECU's (using the tool which makes it comically easy) and looked at all the pins and they looked perfect. No corrosion, no green, no white residue, nothing, they looked great. Nevertheless I hit them with brakekleen and blew them clean with compressed air and reseated them. No change. Tomorrow I will try to see if I can find the little square that corresponds to my #2 plug and see if I can see any breech or issue with the wire seated up in there.

    meanwhile, there are quite a few ECU's on ebay that are compatible with this car for $50-$100 (on FCU euro a new on is $2000). One eBay ad said it 'would need to be reprogrammed'. Is this accurate? If I get a new (used) ECU do I just drop it in or is there something else I'd have to do, assuming I get a compatible replacement that is.

    Thanks, I think we're close here!

    drGian


    PS, don't admire my tenacity, I'm just incapable of being beaten by a ****ing car. I worked hard on this thing, there is no way I'm giving up now, it's just textbook OCD .

    If the ECU doesn't do it, apparently there is a local mechanic who's good with these cars, I might have him have a look. But I'd be surprised if he could think of something I haven't, or nobody here has.

    And if I can't get it fixed, I'll just let my kid have it on 4 cyllinders. She runs really well on just the 4 anyway.
    current lineup: 2001 Volvo v70 2.4 Turbo, 2014 Ford Flex AWD, 3.5 V6 Turbo, 2017 F-150 3.5 V6 Turbo

Page 1 of 4 1234 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •