BPU help

Me and jake 'BPU'ed my j-spec 94 TT 6sp this afternoon, we fitted Whifbitz decats removing both cats, restrictor ring, Walbro pump, NGK BCPR7ES plugs gapped to 0.8mm and a HKS FCD but the car is not boosting anymore than it did before we started, roughly 0.7bar. it is not holding back or hitting any cuts or anything, just not producing anymore boost than standard! all pipes look ok, anyone got any ideas what could cause this?

that's odd, I was getting more than .7bar before the decat and with rought exactly what you have I now get 1.2bar. In the hot weather it can be a tad less (say 1.1 or so but not that low)

what pressure do you get with just #1 turbo on?

have you tried it without the restrictor ring (since all cars are different and some don't need it or need a different size)

also, is your SMIC in good condition?

i think both turbos boost to roughly the same, the intercooler looks ok but obviously thats without taking it off the car, yeah me and Jake were just saying that we should try it without the ristrictor ring and see what happens.

do you have a boost controller? Is this responding to raising boost?

Also, have you tried an ECU reset?

Try without retrictor ring first mate.

Was talking to you Friday Jonboy about you doing the work, (at the Pompey meet), glad you got it done mate, an hope you find out whats wrong.

JonBoy, i've just been doing a bit of searching and i think it could be your Zigen exhaust causing the problem. There are a number of threads saying how 'low key' it is noise wise and also a few mentioning the baffles going...

...maybe the system is too restrictive or is partial blocked, as i have heard of no boost gain if the stock system is still in place when you decat.........

Reset the ecu and take it for a ragging in the evening.

Its been very very hot today and this could result in you not making good bosot...

 

...maybe the system is too restrictive or is partial blocked, as i have heard of no boost gain if the stock system is still in place when you decat.........

Is this true.. I am just about to double decat my TT but leaving the rest of the origional exhuast on. Is it too restrictive? ermmm..???

yes good point, reset the ecu and go for a run when it is cooler, you will need to give it a few full power runs and see if the boost comes up - mine was stuck around .9 - 1 bar until I reset the ecu.

if no good then step 2 is to try removing the restrictor...

Jon's ECU would have been reset when I fitted the FCD, due to disconnecting the battery while hac^H^H^H errr 'adapting' the loom.

spackrackman - I had both cars out with the stock exhaust for a while - its def worth doing as it made a big difference, though obviously witl a free-er flowing cat back system aswell it would be even better!

Have you installed a bleeder 'T' on the wastegate control VSV or a boost controller (MBC or electronic)? Otherwise the ECU will activate the wastegate to not allow above about 0.8 BAR boost.

Have you installed a bleeder 'T' on the wastegate control VSV or a boost controller (MBC or electronic)? Otherwise the ECU will activate the wastegate to not allow above about 0.8 BAR boost.

his car is a j-spec. These cars overboost because the smaller wastegates can't regulate the boost at the right level...

Was talking to you Friday Jonboy about you doing the work, (at the Pompey meet), glad you got it done mate, an hope you find out whats wrong.

Cheers Mate

does it FEEL any different? just wondering whether it could be the boost meter that isn't read right?

be careful if you try it without the restrictor ring altogether, doesn't the HKS FCD leave you a little more susceptible if you over boost?

maybe just a very a small bit quicker but not the differance it should be, just more noisey, the turbos dont sound as though they are working anymore than before, the same whistling pitch if you know what i mean

I think the way to go is take the restrictor out and carefully see what happens.

do you have a boost controller? Is this responding to raising boost?

 

Also, have you tried an ECU reset?

No boost controller unfortunately

JonBoy, i've just been doing a bit of searching and i think it could be your Zigen exhaust causing the problem. There are a number of threads saying how 'low key' it is noise wise and also a few mentioning the baffles going...

 

...maybe the system is too restrictive or is partial blocked, as i have heard of no boost gain if the stock system is still in place when you decat.........

interesting... has anybody else had this trouble with 5zigen cat backs?

just removed the ristrictor ring and went for a blast, it didnt make much differance!

try the ecu reset. If this doesnt work then a boost controller would seem to be the way forward to me (I've got a manual one here you could borrow if it helps...)

is the boost it does get to being maintained solidly? i wonder if there is a small leak that is stopping it from getting any higher? or a stuck wastegate / boost control valve / BOV if any of those would cause this type of behaviour?

are you sure #2 turbo is def working?

Leaking boost would result in some black smoke, more likely one of the IACV valves or actuators not working that can cause boost loss IMHO.

are you sure #2 turbo is def working?

yeah its def working just boosting more or less standard boost. im gonna have to try it with out the 5zigen on and see if its that holding it back