This is a long post, bear with me. I wanted to provide specific details of what I did as to weed out redundant responses. That said, I would sincerely appreciate anyone's help on this issue.

Motor Specs:

• Built motor with 9:1 CR
• NGK PLFR6 (one step colder) plugs @ 0.035”
• Was running -20 mmHg vacuum at idle before transplant

During my inaugural tune on the new built motor on Friday, the tuner stated I was experiencing spark blow-out and I needed to close the gap on my plugs; they were 0.035” – he suggested to close them up to 0.028”. Additionally, he said my vacuum was likely OK (-17 mmHg) but go ahead and check for leaks anyways. At this point, idle quality was perfect, and it ran otherwise pretty good unless you hammered it above 5k rpms – figured I’d trust the tuner’s advice and go home for the weekend.

So this afternoon, I:

• Removed Kinetix plenum, removed cork gasket, replace with OEM gasket. None of the four vac lines were removed at this time.
• Removed all spark plugs, cleaned them up, regapped to 0.028”
• Reinstalled plugs, coil packs, wire harness, etc.
• Performed the 2sec on/10sec off (x 2) throttle body reset procedure.
• Started car: terrible idle quality (rough), vacuum at -14mmHg. Revving it up sounded like it was missing a cylinder. WB said it was lean (~16 to 17 AFR) at idle. Could smell gas in the garage.
• No CEL codes

F* me…

Rechecked all vac lines – all good and snug. No abrasions or cuts found.
Checked all coil packs to assure they were snug and clipped properly – all good. MAF sensor plugged in; TB was plugged in…

First assumption was that it was the intake manifold gasket, so I:

• Removed the intake manifold, removed all 4 vac lines (3 on pass. side and the one in the rear) and made a new cork gasket (pretty damn good if I do say so myself).
• Reinstalled, and triple checked all vac lines to assure snugness.
• Re-performed TB reset procedure.
• Started it: same issues: really rough idle, lean WB reading, gas smell, ~14mmHg vacuum.
• Had friend pinch off vac lines while running – no significant differences found in vacuum quality or metrics.
• No CEL codes

Beginning to think that one of the cylinders was not firing, so plugs were pulled again, regapped to 0.032”, reinstalled while assuring snugness, etc.

Started it: same issues – joy

Decided to let it warm to operating temps and run it around the block to see if I could squeeze a code from it. Lots of backfiring, terrible idle quality, very little power under acceleration. No CEL codes.

Ran a search about coil packs: none of mine show any physical symptoms (no blistering, etc.) Friend suggested to pull each pack and perform a spark test to see if we can find a bad pack/plug. I’m out of other ideas at this point…

Long story short: the car was fine before I dicked it up today - but I can't find what I did wrong, especially without the Cipher tool or OBD2 codes.

If anyone could point me in the right direction, that’d be appreciated. I only ask that you don’t ambiguously state that it’s a vacuum leak…

 

damm don...hope you fix this issue out soon!

to be posting this late you ovbiously have fried your brain for the day trying to figure this deal out

 

Any change an injector plug got lifted off a little in the mayhem? I some times use a piece of rubber hose to daignose a specific cylinder. Maybe one of the springs inside the coil packs that touches the spark plug is tweeked and not touching the top of the plug? While its runnning unplug the coil packs one at a time, the motor will stumble if the if that cylinder is running good. If you unplug one and the motor does not stumble any more than it currently is, then that is the cylinder that is the one having the issue.

 

^ That was what I was going to say. 1 by one remove coils and see if there is a difference.

 

borrow someones cipher, you can kill each cylinder, that will rule that out. i highly doubt you have spark blow out. also, get rid of the platinums. in my past and currently i have had the best luck with just plain LFR6A-11 coppers.


i usually leave them at stock gap with no issues even on high hp cars. dont always believe the hype from people trying to sell you stuff.

when you have a cipher, also raise your idle up as well, that will help with your idle all the time. you can spray some carb cleaner at idle all around and when it sucks it in , you will find your vacuum leak...

 

I had a simular problem and it ended up being an injector clip [ wires ] not pushed down all the way onto the injector . We searched and replaced parts for 3 hours and couldnt find it . I took the car home and kept checking it . Two days later is when I checked the clips .

 

Tried to do this by myself tonight :

Checked all injector clips - all snug
Started car, started pulling the harness clips on each coil:

Cylinder 5: engine stumbled more; vac decreased to -11 mmHg
Cylinder 3: engine stumbled more; vac decreased to -11 mmHg
Cylinder 1: no change (bad?)
Cylinder 6: no change (bad?)
Cylinder 4: no change (bad?)
Cylinder 2: engine stumbled more; vac decreased to -11 mmHg

I'm confident that my 'vac leak' is simply unburned air as a result of the misfiring condition I'm experiencing; is it possible that 3 coil packs are jacked? I bought a used Cipher - should be in by week's end; hopefully it'll give up more info than what I have to work with currently.

Last night I got to thinking that it may also be the CAS, but apparently not judging by tonight's symptoms.

I suppose I could go out and buy 3 new coil packs and all new plugs, but a few more days of waiting for the Cipher won't kill me...

ugh...

The spark blowout seemed plausible because the AFR curve demonstrated some irregularities; maybe it was an impending sign of soon-to-fail coil packs? I'll leave them at 0.032" for now; they are 40k mi. old so perhaps I should just spring for new ones?

Any other suggestions in the meantime?

 

You wont get spark blow out at idle. Just swap a coil pack from one of the good cylinders to one of the ones bad and see if do the unpluging test again.

 

Don,

I have 6 brand spankin new 1 step colder plugs if you need them.. Just let me know..

Ken

 

What are you using for control?

Have you actually driven the car yet? While dealing with UTEC issues I swapped all my coils and one of the used coils was bad. I didn't get any codes at all until I started accelerating while getting on the highway. The car had a rough idle to it and backfired when blipping the throttle, but no codes were thrown until I actually drove it.

The code told me exactly what cylinder it was, I swapped out that coil pack and the car was fine. I then swapped the UTEC out and fixed the original problem.

Side question - how can a Cypher help in this situation? What would you be looking for?

 

Looks like the Driver's side is not firing whatsoever.

Step 1:

Remove all 3 Coil packs from driver's side #'s 2/4/6

Ground threaded potion of plug to block. If you have to use a wire around the threads to a good ground on the chassis.

Crank motor to see if the plugs are sparking.

If Not

Check Cam Angle Sensor Connector

Check Harness. Power Side and ECU side. Check Grounds at front of the Block

Check injectors are receiving signal with noid light or voltmeter. It is unlikely that 3 injectors are clogged at the same time so if they are receiving signal we can assume they are injecting fuel. You can also crank the motor with the plugs removed and try to see fuel spray but not the most reliable way IMO.


If that does not show an issue then

Compression Test

 

That's on the to-do list tonight; #2 appears to be firing, just #1, #4 and #6 didn't seem to show a response when I yanked they clip. I'll try to get smoeone to come over and cracnk the car while I pull these coil packs.

To answer one of the Q's above, yes I drove the car around the block - was backfiring and chugging down the street without almost no power under acceleration - was not in a condition where I could take it onto the freeway without significant risk.

Checked all harnesses, grunds, plug-ins, etc. - all appear to be sound. I'll perform a compression check as a last resort but it was running fine when we drove it into the garage and for the days preceeding this; just that it crapped out at some point during our little plug regapping endeavor.

The spark blow-out did not occur during idle, it was during WOT at 4k+ rpm with 20psi boost. Prior to Saturday night, she was idling great.

The problem is obviously user-related, just gotta find out WTF I did...

 

And still no code? That's a weird one.

For sure keep us updated.

 

PROBLEM FIXED!

She runs beautifully...

the problem was so f'ing simple and stupid, which was clearly my fault (as a I thought) and a little nonsensical crap on Nissan's part... will post in a few - wanting to run this around the block first.

 

subharness on the passenger side??

 

Nope - just me being a dumbass. I wired Bank 2 as shown:



I figured that the wires coming out of the loom would correlate with the location of the coil. Instead, it's supposed to be wired as:



I confirmed this with the wiring schematic. So, can't figure out why Nissan ran the loom like that; more importantly I learned to wire your harness.

Ugh.

Huge thanks to everyone that helped with the problem.

Now onto other issues regarding the car running super-rich and my tuner stating that it's due to spark blow-out... maybe UniChip doesn't allow you to decrease the action potential of larger injectors? Who knows... I'll create a seperate thread shortly about that.