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  1. #1
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    Major misfire - I could really do with some good news....

    Hi Guys,

    Hopefully someone can tell me that my engine is not knackered!

    I was driving up a long hill on the A55 with a car in front doing 70, when he pulled over I accelerated reasonably hard in fifth as there was a Merc up my chuff!
    All of a sudden the check engine light starts flashing and there is a loss of power, accompanied by some smoke but I'm not sure if it is more than usual as she does drink a bit.
    I pulled over into a layby with the engine running really rough and read the codes. P0301, misfire on cylinder 1. I limped to the next services as I didn't like the exposed layby and waited for the RAC man.

    He swapped the coil packs and plugs around but the misfire stayed on 1. The plug for 1 did look rather manky with some hard light coloured deposits. 2 was better but still a bit light. He called it a day and arranged recovery from Wales back down to Kent!
    Now I have her home, I tried swapping the injectors around between 1 & 2, the misfire stayed with 1.

    Right now I am thinking something major is wrong internally, either head gasket, valves or rings. I'll be buying a compression tester tomorrow to see if that is a problem...

    Any thoughts what it might be? Something else to look for? Any help, advice or abuse gratefully received!

    Alex.

    Edit:- Might be useful saying that she is a 1999 C70 T5 ME7.
    Last edited by Alex.; Monday 1st October 2012 at 18:46.

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    Actually, I say it's a misfire, but it is not firing at all!
    If I take the connector for no 1 injector off, no change to engine note. Take no 2 connector off and she starts running on 3!

    Alex.

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    I had a misfire issue months ago and mine was coil packs, but as you have ruled that out by swapping the coils around, do a valve pressure test and see if the dodgy valve is at the same pressure as the others. My bet is a valve issue (i.e. broken).

    If the valve test shows 0 pressure or little pressure on cylinder 1 then the valve is knackered.

    Let me know how you get on.

    Regards

    James
    Last edited by JamesT5; Monday 1st October 2012 at 20:13.

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    Was the spark plug damaged on its end ?.
    The loom to the coil packs can get damaged and short to earth.
    Have you tried the coil pack with the spark plug on a outher cylinder loom plug ?,a short to earth in the plug.
    Have you tested the plug to the no1 coil pack is there any voltage at the loom plug.

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    Good call on the wiring to either the coil or injector, I'll check all the wiring out too.

    For a compression test, what is the correct procedure?

    Remove all 5 spark plugs.
    Screw in tester.
    Fully depress throttle pedal.
    Turn over engine for 4-5 revolutions.
    Read gauge.
    Reset gauge.
    Redo test.
    Move to next cylinder.


    Is that about it? Anything else?

    Ta for advice.

    Alex.

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    As above, "misfire on cylinder.." indicates something's dead in the circuit for that cylinder. My first bet would be the coil pack but since you've ruled that out, it'll most likely be the will be the wiring.
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    Quote Originally Posted by M-R-P View Post
    As above, "misfire on cylinder.." indicates something's dead in the circuit for that cylinder. My first bet would be the coil pack but since you've ruled that out, it'll most likely be the will be the wiring.
    That raises the question of where are the sensors and what are they measuring!

    When the code P0301 is thrown, does the ME7 system actually detect if the mixture in the cylinder is burning or just that the electical circuit to the plug/injector is intact?

    Alex.

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    Quote Originally Posted by Alex. View Post
    That raises the question of where are the sensors and what are they measuring!

    When the code P0301 is thrown, does the ME7 system actually detect if the mixture in the cylinder is burning or just that the electical circuit to the plug/injector is intact?

    Alex.
    Here are some answers to your questions eg: Where is the code measured?

    Don`t freak out at all the suggestions it`s just process of elimination.
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    Thanks for that info, most informative!

    Off to get a compression tester this afternoon and the elimination will continue...

    Alex.

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    Before a compression test take the plug out and put it onto the coil pack either lay the end of the plug close to.the rocker cover or use insulated plyers and get some one to crank it over if there is a electric spark/contact from plug to head you know the coil pack and wireing are fine and its then a internal problem and probley a broken or burnt valve head
    Last edited by t5 pete; Tuesday 2nd October 2012 at 18:15.

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    Any luck finding out the problem yet ?.

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    Quote Originally Posted by Harvey View Post
    Any luck finding out the problem yet ?.
    Well, I think the polite term is 'CRAP!'
    While waiting for the missus to get home and help with checking for a spark, I thought I'd try out my new compression tester.

    Cylinder no 2 was 150 psi, I must be using the tester about right.
    Cylinder no 1 had no compression at all, didn't even register! I took it all apart and tried again with the same results.

    Methinks a valve has dropped!

    Alex.

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    Read my misfire threads on the P2 forum, it shows everything I went through to sort out my misfire. Hopefully there will be something in there you can use, and yes your pressure test process is correct as far as I know.

    Regards

    James

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    Think I'm going to need a new head!

    How much should I expect to pay for an ME7 T5 head?

    Alex.

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    Quote Originally Posted by Alex. View Post
    Well, I think the polite term is 'CRAP!'
    While waiting for the missus to get home and help with checking for a spark, I thought I'd try out my new compression tester.

    Cylinder no 2 was 150 psi, I must be using the tester about right.
    Cylinder no 1 had no compression at all, didn't even register! I took it all apart and tried again with the same results.

    Methinks a valve has dropped!

    Alex.
    Looks like my valve pressure theory was right then. You may not need a new Head, but the engine will need taking apart and a new valve put in and re-seated or whatever they do. This is where my mechanical knowledge is very very thin....

    Regards

    James

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    I would'nt buy a head until you take yours off as it could very well be repairable. On the other hand if it has dropped a valve you could be looking for a complete engine if there's piston and bore damage.

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    If the valve had droped the spark plug would be damaged/bent on the end.

    Found this worth a look before you spend to much cash.

    http://www.vpcuk.org/forums/showthre...it-dam-n-blast
    Last edited by Harvey; Wednesday 3rd October 2012 at 22:40.

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    Had a chat with a garage yesterday and they advised the same thing. Take my head off and have a look, then go from there.
    As there is no damage to the plug, or no sound of contact when the engine is turned over, it is likely that a valve has just burnt.

    Still, a bill for £800 plus VAT is never good....

    Looking at that thread, do T5s have a habit of breaking bits of the valve off? It would explain the lack of other apparent damage and total lack of compression.

    Alex.

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    A chipped off valve could cause loss of compression.

    Has happened before but it's an anomaly

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    Quote Originally Posted by Alex. View Post
    Had a chat with a garage yesterday and they advised the same thing. Take my head off and have a look, then go from there.
    As there is no damage to the plug, or no sound of contact when the engine is turned over, it is likely that a valve has just burnt.

    Still, a bill for £800 plus VAT is never good....

    Looking at that thread, do T5s have a habit of breaking bits of the valve off? It would explain the lack of other apparent damage and total lack of compression.

    Alex.
    Hello Alex, ....are you the Alex that used to have a T4 and did a dyno at Newington because if you are then this is Keith from Hythe that had the `98 T4, do you remember?

    anyway your motor did you use 95ron?........and for how long have you had the car years or miles?

    Keith


 

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