What controls the injectors?

[93_jdm_fd]

I have this misfire at idle. I unplug #6 and #5 coils and they seem like they do nothing when I unplug them. I've swapped these coils with #1 and #2 and still the same. #6 and #5 coils seems to do nothing when unplugged.

So then I swapped injectors from #6 and #5 to #1 and #2. Still the same. So just by feeling the injectors #1 seems weak compaired to the pulse feel that I get from the rest of the injectors. It doesn't matter where the coils or injectors are in the cylinder position, it still misses on the same cylinders. I think the CAS is the problem because my problem seems likes it's caused by whatever controls spark and fuel.

So does the CAS control spark and fuel or just fuel? I've tried a known good ignitor and still unplugging #6 and #5 it does nothing as far as idle dropping.

[ChezoGTR]

have you tried checking your spark plugs?
or done a compression test on the dead cylinders?

[93_jdm_fd]

The spark plugs are brand new(NGK bpr7es) gapped to 0.8mm. I did a compression test on all cylinder yesterday and the average was 155psi. The plugs all had a nice tan color to them to so it's burning properly just at idle is a slight miss. Nothing above 1600rpm and up. I have full boost and no hesitations throughout the rpm range.

That's why I thinks it's fuel related. Maybe one or more injectors are weak and at idle, they're not spraying on time or something. When I increase the fuel pressure by stepping on the gas it runs fine without a miss even holding it steady at 1600rpm. So fuel pump, injector(s), pressure regulator, or if the CAS has anything to do with fuel that could be a problem to? This is where it's nice to have a bunch of spare parts to swap. I don't so it's going to be expensive!! No codes either, i don't really know how to properly check for codes though.

[gezed]

try putting a flat head screwdriver against the injector and put your ear against the other end, this will amplify the clicking and it may help identify which ones are not pulsing properly

[dickered32]

Have you checked you coil wiring harness?

[93_jdm_fd]

I switched out the harness with another one and it's the exact same thing. I have a stethoscope here at work that I'm gonna try out on the car tonight to pin point what injector isan't doing it's job.

[93_jdm_fd]

Anybody have a CAS go bad? What does it do when it's bad? I did find out that it control injector timing and ignition timing, I just don't have another one to try.

[ChezoGTR]

if you had a bad cas or if the cas was starting to go you would feel it through all rpm ranges or in a high rev like 4-5k gtrs have a common proplem of misfiring and backfiring at high rpms and the cas could be the issue there. i would go buy some fuel system cleaner and fut that in with your next fill up or i would check your o2 sensors.

[93_jdm_fd]

I have some fuel injection cleaner stuff that we use here at work when we do a fuel injection flush. I'll try some of that and some octane booster next fill up and see if it helps. What are the symptoms of bad o2 sensors? Or even a bad knock sensor symptom? The rear knock sensor is bolted near #5 cylinder. I've read that it retards timing when it's bad. That's almost what my car feels like at idle. I have timing light now and will check to see what my CAS is set. It should be 20BTDC and if it's off than I know something is retarding the timing.

[ChezoGTR]

well your o2 sensor controls your mixture if and tells the comp to add or take away fuel so if you have a lazy o2 sensor you'll have a rich or lean mixture hopfully rich over lean but you said your plugs are nice and tan color so you'r probably running optima. do the timing light its the easiest ting to do. take a plug wire and rig it to fit into the coil pack on #1 and then put the conducter arount the wire. if all else fails try getting a code from your ecu
www.jdmlegion.com/assets/skyline_book.pdf <---- this will tell you how to get into the diagnostic mode of your cars ecu

[93_jdm_fd]

yeah the plugs have been in since the rebuild maybe a 1000km. Both times I've removed them to check compression they've been all a tan color. So the o2 sensors must be working right. I will check timing tonight and see what's going on. I have a wire already rigged up to test with. I will also check to see if the rear knock sensor is stilled plugged in to.

This all started happening about 500km since rebuild. It didn't have a miss until I reset all the throttle plates and linkage to bring the idle down from a steady 1500. I had to pull the intake off the set the throttle stops. I might have pulled one of the knock sensors off then, it wasn't real fun to remove.

[93_jdm_fd]

Hooked up my timing gun to the rigged up plug wire set at #1 cylinder and found with the CAS centered my timing is way off. I set the gun to ZERO and turned the CAS clockwise to set it at 20BTDC(third mark from the right) and the CAS is pretty much turn all the way clockwise to get it to 20. I can't even drive the car this way, real sluggish. I set it back to the middle where I had it and drove home.

What would cause the ignition timing to be way out? The belt is set right on.