[Mk2] [Turbo] exhaust blowout and low boost

[wazza2]

just took my car out for its first spin after the new engine was fitted. at first everything was fine, no strange noise's and was boosting to 14psi with no problem. Great
but after about 10 miles, a blow-out had developed in the exhaust, which sounds as if its coming from the top of the downpipe. Mite be coincidence but around the same time I could no longer boost higher than 7psi. Are these to related or is the boost issue a result of hitting safe mode?
Cheers

[Lewis Jay]

Have you got a de-cat fitted?

If so, then your wastegate may well be stuck on the downpipe.

[wazza2]

yeah, downpipe fitted yesterday as part of rebuild. How do u mean wastegate may be stuck? wot sympton would that cause?

[Lewis Jay]

Underboosting, blow-out noise at top of downpipe.

Have a look at the actuator arm that connects to the wastegate if there is a shiney section on the actuator arm (about 5mm) that you can see close to the actuator then its stuck open.

You will need to remove the downpipe and grind away some of the inside so the wastegate can move freely, this can be hit and miss as I didnt get it right the first 2 times and have been left with a very thin wall on my downpipe.

Or you can just re-fit your old de-cat after knocking the middle out and solve it first time.

[wazza2]

is this a common fault with aftermarket downpipes? mine is an xs power one

[Lewis Jay]

Yes very common more so with the cheaper XS power ones.

[wazza2]

ok. have car jacked up at the minute and it does look like about 5 - 10mm of shiny rod protruding from the underside of the actuator. im assuming that the actuator pushes the rod out to open the wastegate and pulls it back in to close it? is this rite?

[Lewis Jay]

Yep thats right.

[wazza2]

spot on mate. just got the decat pipe of and hey presto teh wastegate snaped shut. think i'll gut teh std pipe ansd stick it back on and possibly order a better decat pipe
cheers

[Lewis Jay]

No worries.

Knock the guts out of the standard one and put that back on, you dont need a de-cat mate, they are overated I feel.

[lee.w]

Yes very common more so with the cheaper XS power ones.

so why would the more expensive ones fit better ? , I have an aussie dp being fitted soon got it from fensport. it's a good one apparently will this dp have more chance of not getting caught on the wastegate, if so how?

[Lewis Jay]

More expensive, better manufacturing process etc.

Yours will be fine, if its not Fensport will sort it for you.


Ebay downpipes are cheap for a reason.

[wazza2]

ok, had to grind down a bit on the downpipe to stop wastegate sticking open , and aftre a quick run i seemed to have solved that problem. now i've never heard a mr2 turbo with a deact and nur spec before, but jes*s it loud...too loud in fact. do i have a blow out or it that how they shud sound?

[lee.w]

More expensive, better manufacturing process etc.

Yours will be fine, if its not Fensport will sort it for you.


Ebay downpipes are cheap for a reason.

I've just had my system fitted with an aussie downpipe not cheap , and my boost is low and also the boost gauge does'nt go up any more. please dont say my wastegate is stuck on the downpipe aswell

[Lewis Jay]

Possible, but I would check other stuff first.

[lee.w]

Possible, but I would check other stuff first.

what other stuff you recommend

[lee.w]