A fuel injector problem

[firefighterwhite89]

So, I removed my head to replace a blown head gasket and car ran pristine! Now after reassembling, Cylinder 4 is now missing. Plug wires, Dizzy Cap & Rotor, Spark Plugs all brand new and sparking perfectly. Pull plug wire off cylinder 4 and no changes in engine load, or idling. Still the same consistent miss. Compression test at 171.
What else can it be other than the Fuel Injector?
My problem is IDK what the injectors resistance is supposed to be, nor how exactly to tell if the injector pigtail has power when firing.
Any ideas or suggestions are welcome!

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[niles]

It's been a while since I tested mine, but I believe the shop manual lists the procedure and the resistances for the injectors and the injector resistor block on the fender. Did you check for shorts or breaks in the wires?

[Legend_master]

To test the wire, pull the plug wire while engine is running. Ground the wire to something metal and see if it sparks.

[Jafir]

To test the wire, pull the plug wire while engine is running. Ground the wire to something metal and see if it sparks.

I'm thinking that's a bad idea for an injector. Works ok on spark plug wires though.

[Jafir]

r how exactly to tell if the injector pigtail has power when firing.
Any ideas or suggestions are welcome!

noid light.

[firefighterwhite89]

I couldn't find the procedure in the manual or the resistance for the injectors. Anyone know off the top of their heads?
I'm betting its a wire short. It's just the nightmare of tracing the wire harness from the injector back.

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[niles]

Tracing wires is a nightmare, especially when they're all wrapped in a sleeve. The resistance should be around 1.8 to 2.0 ohms if I remember correctly. But don't quote me lol, in a nutshell a bad reading will either be infinite resistance (broken), or no resistance (short). You touch the multimeter probes to the two prongs on the injector to measure their resistance.

I agree with Jafir - noid light will plug in between the injector and the wire harness and lights up when power is sent to the injector. You can rent them from AutoZone, full refund when you return the lights.

If you are getting signal in the noid light the injector might be ceased.

[Jafir]

My 87 manual lists 1.5-2.5 ohms. It also mentions that since you can start the engine, you can use a stethoscope to see if the injector is clicking.

[MessyHonda]

the injectors are easy to replace. last time when I thought my injector was missfiring I took a flathead screwdriver and put it up to the injector and see if you can hear it click thru the handle.

[firefighterwhite89]

Thank you guys for all the tips. I'm fixing to leave work and I'm going to stop and check on a Noid Light. I have a feeling it's a wiring issue. :'(
Ill update all as soon as I get a chance in a day or so.

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[Legend_master]

I'm thinking that's a bad idea for an injector. Works ok on spark plug wires though.

That is exactly what I was saying.

[firefighterwhite89]

Sorry it took so long to reply. Been working lots of extra shifts. Here's the update.
-All fuel injectors test at 2.0-2.1 ohms.
-All prongs on my injector resistor test at 6.1 ohms.

I guess its time to finally remove the stock wire wrap/tape and find a wiring short. :'(

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[firefighterwhite89]

Figured it out though it's weird. There was an intermittent short between the injector plug and the wiring harness plug on my drivers side fender well.
A quick splice and wire and grandpa purrs like normal!

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[firefighterwhite89]

Well I guess I lied. It ran perfect after I fixed it. Go to crank it 3 hours later and go to WalMart, it idled great like before. Go to drive it out the driveway, it starts to miss like a perfect cylinder miss. Again. But only with a load on it. Otherwise, it idles perfect!

Dirt/trash in an injector?

My buddy had this exact issue a few weeks ago with his b16a. I'll investigate it tomorrow.
>_<

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[Dr_Snooz]

When did you last change your plug wires?

[firefighterwhite89]

Brand New With No Mileage:
-NGK BPR-5EY-11 plugs
-OMNISPARK plug wires
-Dizzy Cap +Rotor
-Ignition Coil
-CV Axle(Not Applicable to this issue)
-FEL-PRO head gasket

And I know it's timed right. Last time I timed it with a light, I chiselled a flat mark for it.

After I installed all the new above listed parts excluding the Head gasket, it ran perfect for two days til I replaced my Head gasket and now I had a fuel injector wiring short/though fixed now, still misses like a perfect cylinder miss under load/throttle.

Might I need a new fuel filter? Maybe I got dirty sandy gritty gas(usually happens when the gas station tank underground is being filled or is low)? Could the 'better' ethanol gas be corroding my fuel system since it was NEVER designed for any kind of alcohol anything to be run through it?

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[carotman]

Check the fuel pressure. An insufficient pressure will let the car idle but will missfire under load due to lean conditions.

[lostforawhile]

I've been talking to him on the phone, it seems injector 4 isnt getting power, since the ECU switches ground, and there is a constant 12 volts at each wire from the resistor box, eithier 12 volts isnt making it through the resistor, or there is a break in the yellow wire from injector 4 to the ECU, he had a short in the injector wiring at one point,, it may have done some damage also to the ECU, if the yellow wire just grounded it wouldn't have done any damage, but if it shorted to 12 volts, it might have burned out part of the injector drive circuit

[Dr_Snooz]

Sounds like a problem above my pay grade. LOL

[lostforawhile]

Sounds like a problem above my pay grade. LOL

well he said he has 12 volts at each injector from the box, he's already swapped injectors around, and the issue didn't follow, he also has continuity from the yellow wire to the ECU, apparently there are walmart butt splices involved where the wiring got damaged before, my money is on those before the ECU, butt splices, don't do em!! well unless they are the high quality ones, he's going to run another wire from the ECU to injector 4 to bypass all that mess and see if it functions, I also told him how to make sure there are ground pulses at the pin for the yellow wire to 4, if there aren't any, then it's time for an ECU, sometimes after this many years they just quit

[lostforawhile]

I know the book has dire warnings about testing any of the electronics, but when the book was written, digital meters weren't common yet, the old analog meters would have a voltage across the probes which could cause damage, modern digital ones have such a high impedance,that the ECU doesn't even know it's there, just don't use the diode check or continuity function, those can put voltage across the probes

[firefighterwhite89]

I reran the yellow ecu to fuel injector wire and it idled perfect. Give it some gas under load and boom. We got a miss...again. not sure if it's injector 4 or what. I give up for tonight. I gotta work at 5am so im just gonna limp it to work in the morning. >__<

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[firefighterwhite89]

And I forgot to add. After a short 8 mile drive, after first cranking it and it idling perfect, I stopped to idle in my driveway and that damn miss is back. At idle and under load. Again. Did this exact thing the first time I thought I fixed it with the intermittent ground. Cranked it and it ran fine, under load and after, it missed...same shit, different wiring fix. :-\

Both times I thought I fixed it, first cranked it and it ran perfect and after a test drive, we redevelop a perfect miss...both times.
What could cause this?

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[firefighterwhite89]

I forgot to add this too. Tapatalk wont let me edit posts.
When I cranked it and drove it, it idled rough and 40% throttle or less it misses. Anything more and it runs perfect. Anything less than 40% throttle to idle misses. Any ideas?

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[Legend_master]

Sounds to me like something is heating up and failing. Have you tried changing the fuel pump relay, or the resistor box?