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Discussion Starter #1
Hi guys.

So I have a 08 2.5 bnz 4motion, at the beginning of the year I had a straight through exhaust egr delete, darkside front mount cooler and piping and a remap, all was well with the van but after a couple of weeks the turbo started playing up so I fitted a boost gauge to see what was going on, the boost was spiking to 35+psi on a shock turbo and leaking oil everywhere, so cut a long story short, it now has an organic clutch, and hybrid turbo rated to 260hp supposedly so I took it to my tuners thinking right this will cure the turbo spiking problem and I had it on the rollers and a custom remap to which we did over 100pulls and created 30different maps, 10hours later the turbo is pulling better but the map still looks like a wave it spikes and falls all the time it keeps going into limp mode after 10seconds at anything over 10psi in 5/6th so I can basically only run at 60mph every where unless I pulse the throttle, this weekend I have had the intercooler off and back on, a new n75 all vacuum replaced with silicone cleaned the maf and map sensor, and driving to work this afternoon all was well pulling like a train but after 100miles boom, same old story limp mode. I'm running out of ideas now, does anyone know if i should upgrade the map sensor to 3/4bar or if I might need a new maf or maybe a higher flowing airfilter or maybe the new turbo is goosed also but I literally am struggling to fix this issue now, the only other thing that's bothering me is that there's is a slight oil leak down the front side of the engine possible rocker gasket I hope it's not head, it has no other symptoms apart from the boosting problem, and on hot starts it takes maybe half a second longer to start up. With the mods it has currently it should be a weapon of a van but it's doing my head in, What else should I check guys?
Thanks
ThiggeR
 

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Hi guys.

So I have a 08 2.5 bnz 4motion, at the beginning of the year I had a straight through exhaust egr delete, darkside front mount cooler and piping and a remap, all was well with the van but after a couple of weeks the turbo started playing up so I fitted a boost gauge to see what was going on, the boost was spiking to 35+psi on a shock turbo and leaking oil everywhere, so cut a long story short, it now has an organic clutch, and hybrid turbo rated to 260hp supposedly so I took it to my tuners thinking right this will cure the turbo spiking problem and I had it on the rollers and a custom remap to which we did over 100pulls and created 30different maps, 10hours later the turbo is pulling better but the map still looks like a wave it spikes and falls all the time it keeps going into limp mode after 10seconds at anything over 10psi in 5/6th so I can basically only run at 60mph every where unless I pulse the throttle, this weekend I have had the intercooler off and back on, a new n75 all vacuum replaced with silicone cleaned the maf and map sensor, and driving to work this afternoon all was well pulling like a train but after 100miles boom, same old story limp mode. I'm running out of ideas now, does anyone know if i should upgrade the map sensor to 3/4bar or if I might need a new maf or maybe a higher flowing airfilter or maybe the new turbo is goosed also but I literally am struggling to fix this issue now, the only other thing that's bothering me is that there's is a slight oil leak down the front side of the engine possible rocker gasket I hope it's not head, it has no other symptoms apart from the boosting problem, and on hot starts it takes maybe half a second longer to start up. With the mods it has currently it should be a weapon of a van but it's doing my head in, What else should I check guys?
Thanks
ThiggeR
Sounds like you had this under boost issue before you even fitted your bigger turbo?.
What tuner are you using?
 

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Discussion Starter #3
Yes it seems so, I'm not naming anyone but the original remap was a generic percentage map and now I'm using custom tuning with a rolling road, it's so weird how the problem is so intermittent, this morning coming back from work it was boosting perfectly for about 30mins and then was back to the old tricks again

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Discussion Starter #6
The n75 was replaced, today I have cleaned all electrical connectors and ptfed them and still as soon as you hold it on part throttle at anything over 65 boom soft limp mode instantly, tomorrow I've got a ramair filter going on as when they took the airbox off on the dyno is ran better so I thought it was the paper filter and replaced that so issue still there, I'll try the new filter tomorrow

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Imo standard filters are better, the k and n types can clog the maf with oil and the standard paoer ones are supposed to be good for 250-300 bhp or so ive heard, i changed mine back to standard. Have you tested the maf and boost pressure sensor?
 

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Discussion Starter #9
Imo standard filters are better, the k and n types can clog the maf with oil and the standard paoer ones are supposed to be good for 250-300 bhp or so ive heard, i changed mine back to standard. Have you tested the maf and boost pressure sensor?
i bought a dry foam one because the oiled ones cause problems, for 25 quid ill give it a go.
im not sure how i can chec the maf and map? can anyone shed any light?
thanks
 

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There was a massive filter test on the TDI forum a while back and the OE VAG air boxes usually came out top and the OE paper type filters also filtered better than the oiled cotton or dry foam types.
 

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Imo standard filters are better, the k and n types can clog the maf with oil and the standard paoer ones are supposed to be good for 250-300 bhp or so ive heard, i changed mine back to standard. Have you tested the maf and boost pressure sensor?
The filters maybe able to pass that type of power but there is certainly a problem with the air box the filter sits in. The airbox should be able to keep up with a hybrid turbo but anything bigger it becomes a problem. Because of the volume of air required and the length of time the turbo can suck air at the standard airbox just doesn't flow enough.
Shouldn't be any problems with that side on a bnz even with a gtb17 series hybrid....unless there's something else fitted :D
 

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Discussion Starter #13
I'm gonna do the test for myself purely because when it was on the rollers it ran better with out the airbox fitted, so I'll report back later to see what's what haha

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Discussion Starter #14
Ok guys update, I have replaced the afm map and egr sensors no change, open air filter, no change I had it remapped again by someone different and it drove like it was undriveable so they advised I change the fuel filter so I went to vw got raped for 48quid and put it on... Van was fixed! Runs like a dream power everywhere no boost problems so to save any one a headache in the future I would consider fuel filter as one of the first things on the list! Thanks to everyone for their input I appreciate it.

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Similar problems happen on transit connects,
Low power, hunting on idle, and some weirdealers reason egr faults all can be linked to fuel filiters.
 
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