how a fuel injector ruined my life.
some of you may not know but i couldnt go to the trackday reasons being my motor crapped itsself finaly. well after 240000km of reliable service.
it started off as a missfire when it was cold in the mornings, just a light one. having a wideband afr meter made this easy to see that it was to lean on cold start up. easy fix, with the autronic i increased the cold start fuel multiplier. fixed
after 2 weeks it did it again :S so i re tuned the low rpm fuel sites for more fuel. that fixed it.
then.. the battery went flat, it some how lost its tune after sitting for a week. very strange.. so i retuned. fixed.
and after another two weeks it progressivly got worse and worse till it was missing under boost then just light throttle., so i did the logical thing and put a new set of plugs,and leads into it. that didnt help. ok..
so.. i thought it may may be the cdi unit playing up. i have a spare as one crapped its self earlier due to rain in it lol. it was a fixed one so in ti went. that made no differance. so i put some new coils in.
(the whole time chasing a spark issue.miss under laod while afr is ok)
the new coils made a slight differance. but still not fixed. i checked the wiring from it to the coils. turnes out the wiring was no good. so i made a new harness from the cdi to the coils. no change... f**k!!!
hrmm well i used my old bosses occiloscope to check the outputs on the ecu for the injectors and the cdi unit. they were ok. but being a lcd sreen scope the reponce was not quick enough to garentee a clean signal.
so for the hell of it i changed the crank angle sensor(i had to pull it apart and put a autronic chopper disc in it) that made no differance. gay!!
so out comes the compression testor. yay 5 was down. then 6, then 4, then 3. whoa my motor was dieing quick! ok so i used another comp tester. wtf it was all 140psi hrmmmm.. dodgy comp testor.
still missfirng, comp good. afr good, spark good. mayby its the ecu?? but not an autronic! mayby it was a broken valvespring. i recently put cams in.. so mayby the higher lift fatiged the old springs. oh well after a sold 10 hours changing the head over iin car. (not easy on a gtr) it still missed!!!! grrrrrrrr.
ok must be a broken ring land(s) cos they can give good compression and then not good as the ringland mioves around. oh well il just put my built motor in then.
soo on the weekend i swapped over my engines. pitty our work doesnt have a engine crane jjust a forklift and a big steel tabe. so it was out with the motor/box as one unit onm the crossmember.
anyway i got it done and wtf still missing. but now at idle. f**king hell. cos itr was at idle i could norrow it down to no.4 f**k waht is it.. i swapped my injectors around (there only a year old) and the problem moved. coool spo its a lasy injector.. i pulled the filter out of it and cleaned it. yay no more missfire!! woot and i have a new motor ready for 2 bar eheh
moral of this is never asume something is ok. ie..my new injectors and if its intimitant be prepard for what ive gone thru unless you put it on a dyno. it would of saved me a months stress for the sake a 1 hour on the rollers eek.