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Thread: 4age 20v not running

  1. #1
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    Default 4age 20v not running

    hey all i've been looking for this problem for about the last month now its starting to get to me!
    the car
    ae86 with 4age 20v silvertop
    i've wired in a lt10s microtech with the x4 coils. Cas, tps, vvt and water temp only wired in

    It all started about a month ago when i finally got my car registered, i drove it to work and it would only rev to about 4000 rpm with no power! and if i stabbed the accelerator hard it would die. that afternoon i took it to the tuner , but as we were driving it he played around and said somethings not right! ( obviously) at this point it was throwing rpm errors on the microtech and about 2 streets later i lost all power and limped home at 20kph. To add to this exhaust was that hot it started melting my starter motor wires. the next day it wouldn't even run, that brings us to now where i've spent a few weeks trying to locate the problem. I'm hoping one of you guys have had something similar and can put me on the right track!

    this is what i've checked / done
    replaced spark plugs
    replaced fuel filter
    replaced the 4 microtech x4 wires coming from the lt10 to the x4 cause they have strands of wire broken
    added in an extra earth on the lt10s and earthed the x4 to the engine block
    Got the cas tested - fine
    got the microtech ecu and x4 box tested - fine
    injectors ultrasonic cleaned
    fuel pressure is 42 psi @ 2.5l per minute
    tested ignitions leads no more that 6k of ohms and there a foot long each
    put a noide light on each injector to check to see if injectors had power, also put microtech into test mode and checked all 4 cyls for spark - fine
    removed x4 and coil pack harness and looked at all wiring and resistances - fine
    * i did however come across a startling discovery when i removed my tappet cover to find one of cyl 2 exhaust valve was stuck open fully. after removing my exhaust cam and luckily freeing up the valve i was sure that is was my problem! but nope still no better.
    i had also checked valve timing and compression after fixing the stuck valve - 180 over all pots

    i am honestly out of ideas! any input would be great i'll even recheck whatever people might think is wrong with it. i will try to post up a video of how it runs, it literally runs on 1 cyl @ full throttle - 500 rpm.

    cheers twisty

  2. #2
    Veteran LittleRedSpirit's Avatar
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    Default

    If its getting hot in the pipes while running it must be lean. Fuel would then associatively be the cause. What is your fuel sytem consituted from, pipe sizes, is the reg blocked up? What sort of fuel pump. I assume the injectors flashed away when tested? You said they were cleaned. Thats good.

    One thing I can definitely report is that nobody has ever has success running an na 20v with a microtec. Theres some reason why they dont run good and its to do with how the microtech works, ive read about it but cannot recall the exact details. Google around and see what you can find out about how the microtec works. Where did your current map come from?






  3. #3
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    thats what i thought lean but i also thought retarded timing...

    i am running a bosch 044 inline fuel pump, the standard fuel lines to the engine bay and this is my fuel filter set up
    i think the lines are 5/16 or 1/4 maybe?? unsure of the line size to the filter.

    this is what i found with the stuck valve


    i've done a fair bit of research and there can be a few reasons why they throw rpm error codes, the map is just the start up map from microtech

    this is the first start up and finishing the harness and coils

    this is trying to start it now- although yesterday it would run on 1 cylinder

    and spark and injector pulse


    i did try a different fuel reg and as for injectors i could only get them cleaned because his flow machine would not seal the injectors and everytime they pressured up they would leak fuel.

  4. #4
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    i am going to put a timing light on it today but does anything think it could be the dizzy playing games?? it sounds like it wants to lock up when its cranking over? like its too advanced but i won't know until the timing light goes on

  5. #5
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    When cranking over with timing it was hard to make out but its around 15 or 20 degrees( to the left of the 0 mark on the timing case)...but one thing with the 20v's it goes like 20-15-10-5-0-5 above the crank pulley, is the left side advanced?? probably is a dumb question but my 4afe is the other way around i thought.
    also got some aerostart and sprayed it down the throttles of all 4 cyls and it didn't make a difference to it running any better!~

  6. #6
    Veteran drift kid's Avatar
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    man this is a pickle! and luck? do you have any way of trying a different map on the ecu or a different ecu?

  7. #7
    Veteran drift kid's Avatar
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    oh and are you sure none of the valves, namely the stuck one are stuck again?

  8. #8
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    i'm hoping a mate can plug his lt8 into my car and see what happens...
    no luck yet though and the valve hasn't become stuck again...no idea it did in the first place anyway
    i'm putting it down to cas or ecu now..

  9. #9
    Veteran drift kid's Avatar
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    it is beginning to sound that way sadly

  10. #10
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    i'm at my ends width with this microtech setup
    biggest disapointment by far, i'm gonna try and wire the distributor back in to see if it fixes it

    If your thinking about buying a microtech for your 4age DON'T

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