number #3 not firing , unplug maf and it dies....

[nekoabandoned]

ok ive checked all wires.. and i mean all, when i unplug the maf the car diesheres what ive replaced so far..replaced all coil wiringreplaced all coilsreplaced igniter 3 times...replaced all plugsredid maf wiringreplaced all injectorsreplaced whole injector harnessctsthe list goes on...but yeah i noticed when i unplug the maf the car dies, also its really hard to make it start o.o, number 3 isnt firing at all. it has spark .any ideas?

[89240SXCoupe]

Does your motor cut off/bog when you accelerate with 20% or more throttle? My rb20 is having the same problem as yours + the bogging.

hard to start, dies when maf is unplugged and bogs/cuts off pretty badly if i give more than 20% throttle (according to safc II) 2000-2500 rpm. MAFs is good, i just put in an n60 thats is reading right resistances and voltages(safc II). Im thinking it may be the TPS?

anyone that could help with these weird problems, would help us both :P. thanks

[USMCgetsome]

if it has spark then you need to check the fuel injector it self. maybe the o-ring is damaged or the injector is just stuck in the closed position. Next also check the wiring to see if it's even getting a signal from the ecu. Ensure it's getting good continuity. Also, check your cylinder pressure. then post back up!

[nekoabandoned]

nope doesnt bog, compression is good. i replaced the oring when i replaced the injector and ive checked both wires going to the injector .they both tested 12v any other ideas?

[WhatsADSM]

The ECU controls the pulse width to the injector. Check the continuity between the injector wire and the corresponding ECU pin.

When you unplug the injector connector from the injector and have the key in the "On" position without the car running... If you probe one of the pins on the injector connector it will be +12V. The other will be floating (i.e. about 0V).

Turn the car off and then run a continuity check between the floating (i.e. about 0V) pin on the injector plug and the injector control pin for that cylinder on the ECU. (ECU pinouts are available everywhere online via a google search).

If the continuity is bad, then you have a problem in your harness somewhere. If it checks out good then the problem is probably the ECU.

[nekoabandoned]

ok just got done checking the con. from the injector plug to the ecu pin, everything checks out.. i dont think its the ecu...only way to know is to borrow or get anouther ecu and test it right?

[WhatsADSM]

If you have an oscilloscope you can test that signal, however if you don't (and most people don't) then you will want to get another ECU to try.

You *could* do something crafty and repin the harness moving cylinder 3 and 4 around and then seeing if the problem travels to cylinder 4.... but that is kind of a lot of work.

[virus77]

vacuum leak near that cylinder could be causing it, improper grounds maybe.

[nekoabandoned]

ill check for a vacuum leak tonight, and wouldnt repining the ecu make the cylinders fire in the wrong order?

but i am leaning towards a vacuum leak , when i turn the idle screw all the way down it still stays above 600rpm.

[WhatsADSM]

Now it would not fire incorrectly because I'm not telling you to repin the ignition side. I am telling you that you *could* repin the fuel injector signals.

I believe the RB's are fully sequential so the injection phasing would be slightly off on the cylinders being repinned, but it should still run good enough to tell if the problem has moved cylinders.

But I agree with the above. Check for a vac leak first.

[nekoabandoned]

ok me checking for a vacuum leak turned into replacing all the gaskets on the intake manifold... still not firing, is the cas a possibility?would the cas cause just one cylinder to not fire? would it give spark but no fuel?and are there any relays that could be blamed?

[neonbomb]

Try another ECU before you waste any more time.

[nekoabandoned]

erm couldnt there be a problem some where in the harness i cant track down, what if it blows the other ecu? if thats the problem i rather not be out 2 ecu's.that and how many people have heard of a ecu just not sending signal to 1 injector?..

[virus77]

dont know if it applies to you but on my Z i was getting a weak power signal to my ecu because I was running it through the old Z harness. This was causing a miss at idle and under heavy load, car ran fine otherwise so maybe your ecu is not getting proper power.

[nekoabandoned]

im gunna make a new harness from scratch over the next few days maybe that will fix it o.o

[WhatsADSM]

Almost surely is NOT the CAS. Ignition and all other fueling is working properly.

It IS entirely possible to have a single injector driver go out in the ECU. We already had you check the harness between the injector and the ECU and you said continuity was good.

Which RB is this? if it is a 26 only other thing that I can think that would cause the injector driver to blown out is if the resistor in the harness was shorted.... which we should be able to test for.

[Carl H]

sounds like a fried injector driver...seen it happen before for no apparent reason.might just have been a bad ecu or improper wiring...hard to say tho.only time i have seen injector drivers fry outright is when people install low imp injectors in the engine without wiring an inline resistor pack.

[nekoabandoned]

rb20 and its all completely stock , i would pay carl to make me a harness but ive put over a grand into this pit trying to make it run right. i was going over the harness a few minutes ago and noticed the white/purple wire is ran the ignition harness and the fuel pump is wired in there too... i guess thats why i was running lean. im never letting anyone touch my car again

do you think the white/purple wired with the fuel pump into the ignition would cause the ecu not to receive the proper voltage?carl h, your my hero! i know you can figure this out

[Sil240]

You said you replaced the injector and the o-rings and the ITM gaskets.

Do you know that Fuel from the rail is going through the injector into the cyl???

1- get a screw driver and put it on the injector and see if it is clicking/ticking2- pull the rail and injector.Get 2 wires and some connectors then touch the + & - to their respective terminals on the battery for a second.

You should see the pintle open and close.You will also hear it click/tick.

If you have Fuel and Spark in the cylinder it will fire. Unless the Timing is off, just for 1 cyl........

[nekoabandoned]

heres what 4 hours makes , i know its not a carl h harness but its the best i can do in my kitchen for now hahaalthough i need to figure out the proper placement for the white/purple wire to splice into the fuse box o.odoes anyone know where that darn white/purple goes in the fuse box? i know it needs a 12v and that its for the ign relay, i even made a sub harness just for that one wire because i cant figure out where to put it... im dumb or something
Modified by nekoabandoned at 7:28 PM 7/2/2009

[nekoabandoned]

ok got the new harness installed , still the #3 injectors not firing. we hooked the injector plug up to a spare and wired a stand alone pump up to it to see if it was opening at all . no luck, so the injectors not getting a signal to fire, valtage is correct all through the system ... any ideas?

[nekoabandoned]

erm btw i dont know if this has something to do with it but when adjusting the timing you have to retard the cas all the way to just get it to the center line.. took the cover off and put the crank at tdc everything lines up.

[berman]

there is a few things i would try. 1. you could pull the rail out and leave the injectors in it (if your gonna do this then make sure you clean around the injectors before pulling them out) put the rail with the injectors still in it on a paper towel then have some crank the car over and see if it is spraying out of the #3 injector. 2. another thing you can do is a injector balance test but this involves either renting the tool or buying it. what you do to do this test is: hook up a fuel pressure gauge, then hook up the pulse tester (aka injector balancer test) and prime the fuel key on engine off keep doing that untell the pressure goes steady record that reading then pulse the injector and record what you got after pulsing the injector do that for every cylinder and post what you got for readings and ill try to help you from there. hope this helps

[berman]

also another thought did you do a compression test?

[nekoabandoned]

compression checked out and as stated above we hooked up a spare injector(known to be good) to the harness and wired a fuel pump straight to the spare injector . there wasnt a pulse sent to the injector, im guessing its either the ecu or the cas. is there a way to test either so i dont end up wasting more money o.o

[HxC_Nismo]

mark your cas location on the timing cover so you can put it back on in the proper position, but turn the key on engine off and manually turn the cas and see if cyl. 3 injector is pulsing if not, you either have a bad cas, bad injector or bad ecu. you can swap the injector with one of your other good injectors and see if the miss moves to the other cylinder you swapped it to, and if it does move then you have a bad injector, but if it doesnt then its down to the CAS or ECU. keep us posted.

[berman]

cas?

[berman]

compression checked out and as stated above we hooked up a spare injector(known to be good) to the harness and wired a fuel pump straight to the spare injector . there wasnt a pulse sent to the injector, im guessing its either the ecu or the cas. is there a way to test either so i dont end up wasting more money o.o

did you try pulling the rail with the injectors and and seeing if it sprays when you crank it? another test i could think of doing is with a ignition scope but i dont know were you could rent one of those. the only other thing i can think of is do a voltage drop test go right off the ecu back probe the pin for output to injector and also back probe the injector wire thats from the ecu, turn the car on and see what you reading is. also go on the other side and do a voltage drop. this is kindof hard to explain online but ill attempt to do my best and ill draw a picture of what i think it wound look like and were you should do the voltage test . kindof hard to say with looking at a wiring scamatic for the car. also check the available voltage at each wire by back probing each side and putting one lead on it and the other on battery ground. do all of these test with the car on engine running. if these sound to confusing just let me know ill try to explain them better. and if you really need help you can call my cell cuz im at some family event and would really love for a reason to step otta the room 603-852-2852

<<<<VM>> <<VM> +--------------IJ---------ecu------common ground-

[HxC_Nismo]

cas?

Cam Angle Sensor

[nekoabandoned]

guys i know its either the cas or the ecu, ive ruled out everything else. its not getting a ground pulse to the injector. what i need is a for sure way to test the cas befor ordering a new one.i have a few diagrams on how to test them but they dont quit make enough sense, i dont know if im retarded or i just cant properly follow directions.

but again, ill wires have been tested all grounds have been checked, there are zero vacuum leaks, all injectors have been tested , everything has been checked.it has to be the cas or ecu , neither of which i have access to known units that work. please if anyone knows the proper was to test a cas other than listening for clicks please let me know . thanks