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Thread: s14 missfire

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    s14 missfire

    hey guys after some advice my s14 has started missfiring it only does it when the throttle is held steady so wot is fine I changed the plugs, coil packs and unplugged the lamda didnt make any difference tested the igniter and it was blown so I bought a new (secondhand) igniter fitted it problem still there so tested the new igniter and its blown as well I did not test the igniter b4 installing it but I think something is blowing the igniter and thats causing the problem I ve ordered a new coil pack loom and igniter ( which I will test b4 installing it this time) do you guys have any ideas what could b causing this I suck at anything electrical

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    Might be worth trying an air flow meter and have you checked for vac/boost leaks

    How are you testing the igniters ?as the fact the car runs says to me the ignitors are fine

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    How are you testing that the igniter is "blown" ? If you mean it is not showing the correct figures when fitted, look at the electrical supply and earth.

    Sent from my XT1032 using Tapatalk

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    I have an hks fcon standalone so I dont have a maf if there was a boost leak surely it would leak under wide open throttle I am testing the igniter as it says in the nissan manual with a multi meter set to continuity

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    I m testing the igniter with continuity tests that I got from the workshop manual some tests it shows continuity when its not ment to and visa versa

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    Any other ideas on this have gone over some earths will go over more I DoD think the same thing about if the igniter s falling some of the continuity test it would not work all but that is not the case ?

    Sent from my HUAWEI GRA-L09 using Tapatalk

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    A GOOD igniter would fail in a continuity test, cause that's not how it works. There are transistors inside that work sort of like tiny relays. If the igniter is blown, the engine wouldn't run at all or run really bad like on 3 or 2 pots. (depending on which of the transistors inside are blown, there are 4 for each cylinder).
    Do u have a wideband? It would tell u much more about the fuel mix. If you're flooding the engine specially down low, it'll also misfire.

    Edit: had a good read about continuity tests on the ignitor, it depends on how you measure it, i had mine tested straight front to back, so I1 to E1. I2 to E2, etc and there was no continuity, but this was a working ignitor.
    Last edited by speedingmofa; 30-10-2017 at 08:49.

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    If the ignitor had failed it's unlikely it would run ok on WOT.

    Due to it running ok on WOT, you can almost rule out all of the ignition parts, i'd be suspecting Vac Leak, or Map sensor problem maybe? either of these will significantly throw out the timing and fuel maps on cruise.

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    hey buddy thank you for your input I dont have an afr its on my to do list, with the igniter I did not do a straight test I did e (ground) posi to 1234 neg thats spose to be no continuity then reverse polarity for continuity. Then e (ground) posi to abcd for continuity then reverse polarity for continuaty. Then a to 1 b to 2 3 to c and 4 to d pos to neg for continuaty then reverse polarity for no continuity its really difficult to explain heres is a link to the test I did
    https://www.google.co.uk/search?q=sr...Hjct6aRDj9dYM:

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    hey Hooky I thought the same but on the test I did the igniter it failed and on the origional igniter theres was a raised plastic bubble as if something had blown on the inside . I will look for a vac leak when I get a chance and report back iwas thinking if its not ignition it could b injector problem? am thinking bout taking them out and sending off to get cleaned?
    Last edited by marklee77; 30-10-2017 at 20:35.

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    Hey guys update on this new vac lines new map sensor still doing the same I bought an wideband that I will fit tomorrow I am sure its running rich any more ideas?

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    guys any input on this? am going to try a smoke machine to test for vacume leak took it out for a drive its really strange it idles fine I can push on the accelerater and hold it steady and its ok any where from 1k upto 2k then it missfires pretty much all the way throught the rev range drives normal under full throttle and off throttle

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    ok a bit of an update on this I fitted a lambda sensor and its running really rich it idles at about 11 and when it missfires it's below 10 you guys got any ideas?

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    Quote Originally Posted by marklee77 View Post
    ok a bit of an update on this I fitted a lambda sensor and its running really rich it idles at about 11 and when it missfires it's below 10 you guys got any ideas?
    Can a map go bad ? is it worth trying to get it remapped?

    Sent from my HUAWEI GRA-L09 using Tapatalk

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    I checked the fpr today it was running at 30 psi on idle so took the vac line off to set it at about 44 psi put the vacline on and it dropped right down to about 30 again Ive adjusted fp to 40psi on idle any ideas does this sound like a vacume leak? is there a test kit I can get to locate leaks?

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    any help appreciated

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