R34 Down On Power

[SLEEPR85]

Ok guys recently had new turbo put on and tune on 13psi makng 240kw's and loving it, the other day I was just cruising in 4th, then (for whatever circumstance) dropped into 2nd and flattened it. After this looked in my rear view mirror and there was a massive puff of black smoke, and driving seemed to bit flat... long story short, it now doesn't seem to be making much boost. It still spools and I can feel it start to pull but after hitting 4k it kind of just flattens off and has NO top end power.

So, doing a bit of research on this forum some guys have complained of melting metal cats so took that off and had a look and doesn't seem to be 'melted' at all so I'm assuming it's not that. Also had a look at all intercooler pipes and doesn't seem to be any cracks or loose fittings.

Could this be a spark issue? Coilpacks?

I understand black smoke is overfuelling problem, but has only happened that one time and has not been smoking at all since... and having an aftermarkt ecu I would assume the tune would take care of and r n r issues. Also like to add that exhaust note has changed, seems a LOT quieter than previously.

Really starting to upset me, any help appreciated!

Edited October 21, 2009 by SLEEPR85

[SLEEPR85]

A little update, pulled coilpacks and spark plugs out last night and had a look, all looks ok, also checked AFM and found it was clean as a whistle!

Really stumped guys!

[Bunta]

how is it driving off boost?

[SLEEPR85]

Well it was idling a bit rough last night, not violently shaking or anything just a bit rougher than usual, was enough for me to notice. Driving between idle and 3k seems a bit sluggish also before the boost comes on, then it kinda of spools and doesn't really convert into power....

[urtwhistle]

is the waste gate jammed open?

can you hear any random vacume leaks?

[wolverine]

leak/split in intercooler hoses.

[SLEEPR85]

i had thought of that and thoroughly checked ALL connections and piping last night and came up trumps!

[EdGTR]

How does it free rev does it feel normal? If it doesnt take the cat off again and give it a rev to be sure it is a blockage in the exhaust. It will be LOUD. You could drive it up the street but you might get locked up. How much boost is it getting up to and is it blowing any black smoke anymore. What ecu is it and can you check the sensor inputs especially coolant temp incase somthing has gone wrong and its seeing very cold will make it rich.

[SLEEPR85]

Revs feel a bit choked, that's why i thought it was the cat.... not blowing black smoke anymore, just that one time. Running emanage ultimate ecu, still boosts to over 10psi but haven't really fully booted it. Where would these sensor inputs be?

[SLEEPR85]

Was speaking to a mate of mine who has owned and built a few skylines and he suggested that the front compressor of my 2835gt may had let go, does this seem likely? Still boosts but sounds like its sinning twice as hard to get half the power i was getting....

Took the pipe off from the turbo to the intercooler to see if there was any oil leaking anywhere but didn't feel anything. Apart from taking the front intake off the turbo to get to the front compressor (which is surprisingly hard to get to) is there any easy way to know if the turbs is blown or not?

[EdGTR]

Hows it going? Have you sorted it out yet? Most aftermarket ecu's have some kind of sensor check or data readout. i dont know about emanage though.

other than buckets of grey (oil) smoke coming out the or bad noises the only way to check your compressor wheel is to get your fingers to it and check for play. if they do let go its prob best to check it. You dont want it in your engine.

Let us know what yo find

[SLEEPR85]

Ok an update for anyone's future reference.

Took it to my mechanic, said really couldn't fault it in many ways, except when he looked at the sparkies they seemed to be white which would mean that my engine is running lean... suggested i put it on the dyno for a more accurate reading of afr's, etc.

Ended up being injectors were set close to 100% duty cycle and was causing them to cut out at high revs, so my tuner said he dropped it and lowered boost by 1psi down to 12psi.... which still made the same kw's as at 13psi....

Now the question i have now is why would they just start doing that all of a sudden? Do they have a default "safe mode" that when they hit 100% they automatically go back to standard? Think its upgraded fpr time!

[STATUS]

leak/split in intercooler hoses.

BINGO check the 2.5" 90 degree elbows under the filter, its common for them to split.

[STATUS]

Ok an update for anyone's future reference.

Took it to my mechanic, said really couldn't fault it in many ways, except when he looked at the sparkies they seemed to be white which would mean that my engine is running lean... suggested i put it on the dyno for a more accurate reading of afr's, etc.

Ended up being injectors were set close to 100% duty cycle and was causing them to cut out at high revs, so my tuner said he dropped it and lowered boost by 1psi down to 12psi.... which still made the same kw's as at 13psi....

Now the question i have now is why would they just start doing that all of a sudden? Do they have a default "safe mode" that when they hit 100% they automatically go back to standard? Think its upgraded fpr time!

more likely boost cut. The emanage does not care whether its in the high or low octane map.