epic boost problem (20psi+!!!)

[streatracer]

recently Iv been driving my fiances daily (E39 VR4) and it is overboosting HARD. at low revs (below 4000rpm) it holds .7bar just fine, but at high revs boost climbs up to 1.5bar+ if you keep your foot flat (and don't pay enough attention to your boost guage!)

Iv been referred to this site as I deal mostly with nissans and you guys are the mitsi gurus any help much appreciated

EDIT: Sorry forgot to mention it runs td05, 3" exhaust, divorced dump with screamer, and a chipped ecu

 

[bazeng]

No bleed valve at all?
Stock?

Standard engine? Not a stroker or anything like that?

 

[Dean]

What sort of boost controller is it running?
Can you please put your location in your 'User CP' for us too please mate.

 

[CLuTZ]

My EVO 1's boost is spiking aswell, as soon as I put a larger dump on it

 

[rob323]

A common problem in 16g's, grab a GT pumps exhaust housing, port the wastegate area or restrict the exhaust to reduce the creep.

 

[streatracer]

No bleed valve at all?
Stock?
Standard engine? Not a stroker or anything like that?

standard engine. no bleed valve at all.

Can you please put your location in your 'User CP' for us too please mate.

done. sorry bout that.

A common problem in 16g's, grab a GT pumps exhaust housing, port the wastegate area or restrict the exhaust to reduce the creep.

if that's the case then then the aftermarket dump will certainly be making it worse!
would you recommend fitting a factory dump as a 1st attempt to fix problem?
How would you recommend restricting the exhaust?
would welding the gate shut and using an external gate fix the problem?

 

[rob323]

standard engine. no bleed valve at all.

So standard TD05 14B turbo as well?
Boost creep is not usually a problem with 14b's unless the actuator is not opening fully due to the screamer mods restricting it.

would you recommend fitting a factory dump as a 1st attempt to fix problem?

Yes. If the turbo is a bog 16G, then fit a GT pumps exhaust housing with the enlarged wastegate passage.

 

[Fugitiv]

My VR4 has also done the same. All i did was put a dual stage boost controller on and set it to 10 and 15 psi, holds flat on both and goes no further.
Also, i have a 16g with evo3 dump and 3 inch exhaust.

 

[streatracer]

So standard TD05 14B turbo as well?
Boost creep is not usually a problem with 14b's unless the actuator is not opening fully due to the screamer mods restricting it.

Yes. If the turbo is a bog 16G, then fit a GT pumps exhaust housing with the enlarged wastegate passage.

I think it's a 16g (evo 3? will check asap) do you have a rough idea of cost for the exhaust housing?

My VR4 has also done the same. All i did was put a dual stage boost controller on and set it to 10 and 15 psi, holds flat on both and goes no further.
Also, i have a 16g with evo3 dump and 3 inch exhaust.

I'll borrow a boost controller and give it a go

also gonna test the actuator (apparently it's common for them to fail?
)

 

[SIVART]

old/split vaccum lines or, like me fit them the wrong way around

 

[milkandoj]

If it was the common creep casued by the small wastegate passage, wouldnt the screamer pipe help? as it has no restriction being plumbed atmo, rather than plumbed back in.

As the main outlet has some restrction from the rest of the exhaust, wouldnt this differnce help the gate flow more and not creep?

Either way i wouldnt think fitting a stock evo dump pipe will help the issue as the wastgate passage will flow 'worse' than a screamer pipe would and creep harder.

Id be looking at other things first like vacume lines as metioned. Or actuator stuffed.

A quick way to rule this out... Run a fresh piece of vacume line from the intercooler pipe strait to the wastegate actuator. And block up the other lines you dissconect to do this with a screw.

If its only running minimum gate pressure it'll be 7-8psi, no higher.

If it still over boosts id look at the actuator being stuffed. Or at least you have eliminated this one thing. And the boys can help you further.

If do this before buying a stock dump.

 

[blackers10]

mine overboosted after driving 1000km from sydney to brisbane..
found out when it hit 26psi and the rod exited the block(owned the car 12 hours..or so...) was tuned for 20psi with evo 3 turbo and 3" exhaust etc.

will find the problem once i get my new motor in..

my engine builder mentioned using a pop off valve so once it reaches X psi it lets go and stops the engine being demolished via extreme overboost..

 

[BYBY5L]

try blowing air into your actuator, if ya can blow air thru, its poked, just changd 1 about a month ago an i was changing boost hoses every thing, would have saved me a heap of time an it only takes 2 secs to try,

edit; it saves over boosting ya engine 2 an wiggle the shaft as ya do it,

 

[rob323]

If it was the common creep casued by the small wastegate passage, wouldnt the screamer pipe help?

Not really as the screamer is after the wastegate passage and it's the wastegate passage which is the restriction. Porting does help in some cases.

Id be looking at other things first like vacume lines as metioned. Or actuator stuffed.

A quick way to rule this out... Run a fresh piece of vacume line from the intercooler pipe strait to the wastegate actuator. And block up the other lines you dissconect to do this with a screw.

Agree, good tip.

 

[streatracer]

Id be looking at other things first like vacume lines as metioned. Or actuator stuffed.

A quick way to rule this out... Run a fresh piece of vacume line from the intercooler pipe strait to the wastegate actuator. And block up the other lines you dissconect to do this with a screw.

If its only running minimum gate pressure it'll be 7-8psi, no higher.

If it still over boosts id look at the actuator being stuffed. Or at least you have eliminated this one thing. And the boys can help you further.

If do this before buying a stock dump.

I'm heading out to buy new vacuum line soon. gonna replace all boost related lines and tidy up a bit. will be running seperate lines to actuator and bov etc so I don't have to run any T fittings.

try blowing air into your actuator, if ya can blow air thru, its poked, just changd 1 about a month ago an i was changing boost hoses every thing, would have saved me a heap of time an it only takes 2 secs to try,

edit; it saves over boosting ya engine 2 an wiggle the shaft as ya do it,

Just tried this (even though I was a little uncomfortable blowing something while wiggling the shaft ) It held air so Im assuming it's ok.

 

[bazeng]

Double check all your vac lines.

You may have an issue with the plumbing...

It shouldn''t creep THAT much...

 

[BYBY5L]

haha yea probly didnt sound the best huh, good luck man, sounds like you'll get it sorted by the w/e

 

[BMGTZ]

Im happy to take a look if you want to drop by over the weekend.....im south of river

 

[streatracer]

haha yea probly didnt sound the best huh, good luck man, sounds like you'll get it sorted by the w/e

hahaha yeah might take a look at it on sunday as Iv been flat out getting the drit car ready for tommorow.

Im happy to take a look if you want to drop by over the weekend.....im south of river

dude thats very generous of you! I appreciate it and if I cant sort it on sunday I'll shoot you a pm. thanks

 

[kaotik]

Not sure if this helps but my little brothers Cressida (7mgte) just went from runnng 15 psi on a very free flowing single chamber dump to running the stock 6psi with a more restrictive dump with split recirculating pipe.

Ide say the screamer would be playing a part