Another Rb25 Misfire Topic

[fmlycar]

Pressure tested it today and found a hairline crack about 1/4 inch long on 1 intercooler pipe. Can't put a silicone joiner over it in the interim because whoever made the pipe, squashed that particular piece to an oval shape so it won't seal. Found 2 others leaks, 1 was the idle adjustment screw and the other was the bov but that's out of a factory hole cast into the vavle.

[Scott Black]

I don't know anyone with a smoke machine.

i got one at my workshop

[fmlycar]

Replaced cracked intercooler pipe, problem is miles better but still exists. Only on boost and only in low boost range. Once it gets 4-5psi in its guts it clears up and revs like normal. Get an occasional backfire as it's trying to build boost.

[Cowboy1600]

Sounds a lot like coilpacks.

Got access to a known good coilpack?

[scotty nm35]

The tune sounds way out, was the leak there when you tuned the car?

[fmlycar]

Car was tuned in Feb and hasn't faulted since, pretty certain leak was a new problem. It reared it's ugly head after having a boost spike of 6-8psi briefly while setting up a boost controller. I'll try some known good condition coil packs.

Edited July 16, 2015 by fmlycar

[scotty nm35]

Coils generally get worse with boost, not better. Can you borrow a known good set? I doubt it's your issue, but who knows.

[Ben C34]

Car was tuned in Feb and hasn't faulted since, pretty certain leak was a new problem. It reared it's ugly head after having a boost spike of 6-8psi briefly while setting up a boost controller. I'll try some known good condition coil packs.

As in, car was tuned, then you put in a boost controller, and it overbooosted then misfire started.

That's kinda bad.

[Hadouken]

Put car on dyno

As has been said, coil packs fail as boost gets more because the spark generated is weak and then it "blows out".

[fmlycar]

Yeah it over shot and I backed off as soon as I seen it going past where it should be.

Just pressure tested again and found a line teed off from the boost guage line was leaking slightly. Have fixed that. Went for a drive and hasn't made much difference. Only other leak is out a small hole cast into the bov but that can probably be ruled out if it's always been there.

Car was tuned to 18psi. Ebc is in preparation for another turbo upgrade so I can run a couple boost settings. Everything suggests healthy motor, and tune was very safe as that's what I wanted. Knock never goes any higher than 30 at any given time but is for the most part under 20. Tool it for a high speed run last month and never went above 18 in all gears right up to 6500rpm in 5th

Edited July 16, 2015 by fmlycar

[fmlycar]

Closest dyno is 1500km so that option is kinda ruled out at this stage.

These are the joys of owning a car like this in the middle of bumf**k

[Ben C34]

Disable boost controller, does it still misfire?

[fmlycar]

Yep, that was one of the first things I did.

Just blanked of bov and took it for a drive and didn't make much difference. Have attached pics for reference

[Ben C34]

Pics of what?

[fmlycar]

My bov. Quick search of the part number and it looks like it's a gtr item. Going to try and tee up some coil packs and see what happens

Edited July 16, 2015 by fmlycar

[fmlycar]

Tried another set of coil packs and problem still exists.

Possibly fuel pump or crank angle sensor?

Edited July 20, 2015 by fmlycar

[fmlycar]

Took cas off, removed cover surrounding plug and sprayed inside as best I could with circuit board and contact cleaner. Reinstalled and set timing. Has now moved the misfire to more than 1 bar of boost and cleared up down low. does this sound like I should replace it?

[Hadouken]

Probably. If cleaning it made an improvement

[tridentt150v]

Did you rest your timing and a small thing but 15 degrees at 650rpm for a gts25t??? That is not the orange line - each line is 10 degrees.

Mind you, I don't think thats the problem but just to be sure.

[fmlycar]

Isn't it 20 degrees btdc for series 2? I did 15 to begin with and ran like a complete bag of poo, then set it for 20 and was loads better, but not perfect. I'll check tps values again just to be sure and try borrow a working cas to see if that's it