5th Cyl not firing...

[rimbimbambo]

So I found out one of my cyls weren't firing after bringing my car to air care... I sorta assumed something was going wrong when the idle was getting a little rough. Removing & plugging in the wiring to the #5 coil pack doesn't change the idle while its running.

1st assumtion: coil pack
- removed the #5 coil pack harness - No change in idle - swapped the coilpack with the #1 cyl's... Number 5 cyl still not firing...

2nd assumption: Spark Plug
- Replaced the #5 NGK 7mm (I think... the numbers didn't make sense to me) plug with an iridium NGK 6mm... Cyl still not firing...

Other symptoms:
- lightly pressing on the gas very lightly makes the car jolt slightly as if no gas is getting to the cyl and then the right amount - revs go from 1000 to ~1200 as if someone were tapping the pedal quickly.
- Failed aircare for Hydrocarbons (.800 when required .500) - Not burning all its fuel.
- idle gets a little rough after things have heated up - but not horrible.
- Its 4500 kms into its last oil change - Yeah I'm gonna bring it next week.

Where I'm at:
Possible problems -
1. Compression is hooped.
2. Injector may be dirty.
3. Wiring to coil pack may be screwed.
4. Malfunctioning coil pack controller.
5. Just needs an oil change

Any insite on this? I mean am I going in the right direction? Any other suggestions? I'm definately not a mechanic so my tools and work space are limited (I do all my work on the street. It sucks). Anyone got any more quick things I can check before I bring this to a real mechanic? Thanks

[PopolZ]

if you wiggle the wiring of the injector on cyl 5 does the idle change??? I've had that problem before. It would sound like a subaru and the idle was very rough.

[cbileske]

yeah go over the connectors to the the injector and the connector to the coil, could be that the harness is worn out and possibly arcing to ground or to another conductor. Mine has done that before and it was a little loose on the 2nd injector. also maybe clean and dielectric grease the connectors into the ingition box at the back of the spark cover.

[Bruizer]

As for failing aircare, if your not igniting on #5, it could be all it's fuel is going out the tailpipe causing the bad values or you are igniting but no fuel is going in, at this point I'd expect better air care values as you'd run much much leaner lol. You could have a bum injector...... Did you check the output of the ignition transistor? There may not even be anything going to the coil on #5. If there's nothing going out of the ignitor for #5, check for anything going it, if not, your ECU output could be out.

Obviously, your coil is alright if a functional coil didn't change anything unless you used the good coil from another cylinder and had no coil on the other cylinder, then you still have 1 cylinder not firing lol.

ECU pin #2 is your output for cylinder #5. Pin 5 on your ignition transistor is for cylinder #5.

When your car is idling, on the ECU pin you should see around 0.3volts to ground on a good meter (if you have a good scope meter, you'll see the ignition "spikes" otherwise, even a good meter might miss the pulse...). On the line side of the ignitor, you should see 0.3 volts or so to ground. On the output side of the ignitor you should see about 14volts and you should find 0 volts between the E terminal of the ignitor and ground.

If you think the injector isn't stroking, pull the injector connector off and meter pin 1 and pin 2 to ground. On pin 2, I think you'd get about 8-9 volts when running idle on a good signal. Pin 1 you'll see the battery voltage. If you are getting good values but you don't think your injector is stroking, check the resistance of the injector, expect 2-3Ω. If you aren't getting good values from the injector harness, check the ECU pin 110 (injector #5 output) for 8-9volts to ground.

This should be good places to check if the simple stuff doesn't work. Have fun!!

[rimbimbambo]

PopolZ & cbileske - Cool I wiggled the coilpack harness and didn't noticed anything, but I didn't think to test it out on the injector.

Bruizer - Thanks for all the info... checking the electronics was next on my list, but I hadn't tracked down my meter at the time. This will give me a crapload of direction. I'm not very good with electronics but I'll be able to figure out what to do with all that.

Thanks guys!

[rimbimbambo]

As for failing aircare, if your not igniting on #5, it could be all it's fuel is going out the tailpipe causing the bad values or you are igniting but no fuel is going in, at this point I'd expect better air care values as you'd run much much leaner lol. You could have a bum injector...... Did you check the output of the ignition transistor? There may not even be anything going to the coil on #5. If there's nothing going out of the ignitor for #5, check for anything going it, if not, your ECU output could be out.

Obviously, your coil is alright if a functional coil didn't change anything unless you used the good coil from another cylinder and had no coil on the other cylinder, then you still have 1 cylinder not firing lol.

ECU pin #2 is your output for cylinder #5. Pin 5 on your ignition transistor is for cylinder #5.

When your car is idling, on the ECU pin you should see around 0.3volts to ground on a good meter (if you have a good scope meter, you'll see the ignition "spikes" otherwise, even a good meter might miss the pulse...). On the line side of the ignitor, you should see 0.3 volts or so to ground. On the output side of the ignitor you should see about 14volts and you should find 0 volts between the E terminal of the ignitor and ground.

If you think the injector isn't stroking, pull the injector connector off and meter pin 1 and pin 2 to ground. On pin 2, I think you'd get about 8-9 volts when running idle on a good signal. Pin 1 you'll see the battery voltage. If you are getting good values but you don't think your injector is stroking, check the resistance of the injector, expect 2-3Ω. If you aren't getting good values from the injector harness, check the ECU pin 110 (injector #5 output) for 8-9volts to ground.

This should be good places to check if the simple stuff doesn't work. Have fun!!

Hey Bruiser, sorry to revive this thread, I finally got some time to take a meter out to the car and test out some values. The only thing that seems out of the norm is the voltage to the injector (Its about .58 volts). The resistance is 2.2, the battery voltage is about 14 volts, the transistor is sending the same signal to all of the coilpacks (I replaced both the transistor and harness).

I actually found a leaky injector while I was trying to fix this problem and replaced it. My guess is that it was failing aircare because of the leaky injector.

Anyways this poses me with a different problem now... What do I do? Replace the ECU? Should I bring it to a shop for this? Could it be the Harness?

Cheers man I really appreciate the direction. Its helped me a crapload so far.

[DeviantRebel442]

Might mean time for a rebuild...a cylinder not firing means a few things...in order to fire, spark, fuel, and compression are needed....

if one of those is missing there is no firing....my assumption is that your compression is low if you've checked everything else....have you done a compression test yet....

Also i doubt this is an ECU problem....really seems slightly far fetched....

[rimbimbambo]

Ahhh those are the only words I didn't want to hear.

Don't the 5th and 6th tend to go at the same time? I think the 6th is fine...

[BNR32-63]

Could be a vacuum leak, does the car run fine under boost?

Switch injector wiring from another injector to see if it changes which cylinder isn't firing.

You should be able to feel the injector firing if it is, could simply be a poor connection or bad injector.

[malibusst]

have you checked the ignitor???? ive seen them cause a problem as well...

[Bruizer]

Read a little higher, he replaced the transitor (ignitor) and harness.

[Bender]

where abouts do you live in vancouver?

[rimbimbambo]

Kits. 29th & McDonald.

If you wanted to see what it was doing I could drive to ya. My days are pretty open since my company is going under cause of this market ****. By the way if anyone needs a programmer...

Runs fine under boost... in fact I wouldn't have thought anything was wrong with it when the throttle is going. Then again it may have been misfiring when I bought it, so I don't know if its meant to feel like it does.

I was gonna swap the injector connectors but I wasn't sure if that would screw up things because of the timing. Also there isn't really enough slack to get the connector to another injector.