Random missfire

[nidr0x]

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[steve shadows]

What about your coil pack harness condition? Also any screwing connections or shotty connections at all with the air flow readings or the ignition output to the coils will cause this problem. It's usually the ground for the coil pack harness but can sometimes be something more insidious with the actual wiring harness.

[nidr0x]

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[ultimateirving]

Coil packs that are going out can cause a bad misfire thru the RPM range.
Have you pressure tested your system? as in a boost leak tester?
Also what gap are the plugs set to?
and is the misfire only at WOT or is it under any load?

[nidr0x]

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[nidr0x]

The problem continues

[ultimateirving]

Originally Posted by nidr0x

The problem continues

Ok, what about the coilpacks. Have you put in a new set to rule them out?

[cotbu]

It's timing!<---at least that's where my moneys at! Make sure, you sync NDS with the crank. You need a timing light for that. 15degBTDC

The coil pack harness condition is apparently ok. How is located the ground of the coil pack harness? thanks

locate the coil pack harness, look for a random ring terminal. if you follow the harness it'll be connected or not.

[nidr0x]

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[nidr0x]

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[Croustibat]

Originally Posted by nidr0x

The gap are stock (before, i have another plugs, NGK BKR7EIX, now have BCPR7ES copper)

Here is your problem. Stock gap is 1.1mm on these plugs. Set it at 0.8mm (or smaller if your spark system is weak. You should not need to go under 0.6 though)

[nidr0x]

Originally Posted by Croustibat

Here is your problem. Stock gap is 1.1mm on these plugs. Set it at 0.8mm (or smaller if your spark system is weak. You should not need to go under 0.6 though)

But… with the BKR7EIX have same problem (and used it for 10.000 km without any problem)

[DiamxndCrew]

If its running lean why would it be an ignition or timing issue? There's not enough fuel in the cylinder chamber to ignite the mixture. Check your a/f ratio off idle that should help you with your diagnosis, because you need to get data when the problem is occurring.

[nidr0x]

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[cotbu]

The ecu can and will pull timing! Check your timing! A random misfire yeah it pull timing just for that. Half Broken Things?

Sent from a Highly Tuned SIII using Tapatalk HD

[nidr0x]

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[snafupossum]

what is the voltage at these cut outs? any time voltage drops below 14v sr's like to act funny

[Kingtal0n]

when you say misfire, do you actually feel the misfire? You feel the engine kick?

And, is it several in a row? Or just one here and there at random. I know you said at random but several in a row at random or just 1 at random?

Do all the plugs look the same when you check them?

Do a compression check. Do a leakdown test. Inspect the valvetrain. Listen for odd noises. verify the plugs all look the same. Fill the plumbing with 15psi with the engine off and check for boost leaks.
replace the ECCS relay with the relay for the cruise control (exchange them). verify the ignition timing like cotbu said also.

are you SURE it doesnt get worse during wide open throttle?

[nidr0x]

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[Kingtal0n]

Originally Posted by nidr0x

I feel random missfire like fuel cut, the car goes too lean when misfire, but 1-2 seconds laters the wideband reads good. Its totally random… 2000 RPM, 3000 RPM, 5000 RPM.

I dont inspect the plugs beacuse are new, but tomorrow i unmount and make photos to this.

No rare cold noises. One question, what is the relay of cruise control?

The ignition timing its ok.

I tried to change the fuel pump to a new walbro, but same problem, tried new coolant sensor, but same problem

it sounds like your ignition is cutting out randomly. but that would be multiple cylinders at once. so you need to try and answer my question: is it several cylinders in a row (several misfires) or just one cylinder (a quick pop).

You are saying like a "fuel cut" which would be like hitting a brick wall for a moment. does that sound right? So multiple cylinders at once. That points to: ECU, CAS, Ignition harness, ECCS relay, Ignition switch

[nidr0x]

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[nidr0x]

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[Kingtal0n]

Are those backfires when cranking? Its cranks for a few seconds, then backfires, then cranks more? do I hear correctly?

I would start with the basics. Check compression. Check leakdown. THEN install all OEM equipment, factory fuel injectors, factory ECU, etc... everything back to stock. reset the ignition timing by eye and then with a timing light. Make the engine like brand new again. Make sure your injectors/rail is not leaking. verify fuel pressure.

Then, your starting issue should stop, and if not, diagnose that first before moving on to the misfire issue. they may be related.
if the computer IS already stock, i would replace that first.

[nidr0x]

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[nidr0x]

Any help?

[Sr20Bluebird]

that's really strange. Some time ago i had a similar situation with my sr back firing when i tried to accelerate. Especially under a load. Turned out to be a bad exhaust gasket off the turbo to my down pipe. As far as the hard starting i would go back to basics. Check for spark after the car has warmed up. You have compression, sounds like to have fuel but again i would check it once its warmed up. Remember that heat causes parts to expand and contract. Maybe once something heats up it makes a bad connection and gives you your problem.

[nidr0x]

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[ultimateirving]

I think you should get a fuel pressure gauge too. You cant assume the pressure is good just by replacing them.

[Jerzydood]

I had the same issue with my car, would break up and miss around 2500-6000 than TAKE OFF to 7000k +. The idle was rough and it sounded like a Subaru. Sounds like a Subaru cause you are running a cylinder down. "dead cylinder"....I changed plugs, wires, coil, rotor, cap, tested igniter ECM blah blah blah....turned out to be a injector. Does the car idle funny??

[nidr0x]

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