Low boost - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

D. Joy · 03-26-2011, 10:57 AM

Just recently bought an s13 with a Ka-T setup. Was garaged for about a year before I came along and supposedly was working fine when it was parked.

Went to drive away and we find out its not building boost, maybe about a 1lb. Un-did and re-attached all the intercooler piping and couplers to make sure there were no vacuum leaks and still ended up not building boost.

Anyways, got the car home and took turbo setup apart and found some oil in my hot pipe and couplers. Does that mean I need to replace the seals in the turbo? There's no shaft play so I don't think its blown...

Would the damaged seals be reason for no boost? Can anyone point me in the right direction? thanks.

hartig · 03-26-2011, 11:22 AM

this might sound dumb.. but did you check the wastegate/ wastegate hose?

D. Joy · 03-26-2011, 03:21 PM

Yeah, but I don't know exactly what to look for, except for a possible leak in the hose and that the waste gate can open and close. Both seem okay, no leak and the gate moves by hand with a little effort.

Drifting-pedobear · 03-27-2011, 04:07 AM

wouldnt be the wastegate, you would have the opposite issue, too much boost.

my money is on the turbo being lop.
is it a s13 sr turbo?

more details about the motor would help...

titangts · 03-27-2011, 08:27 AM

are you running a blow through set up like maf before the TB? or standard before the turbo..if blow through make sure your bov isnt stuck open lol. im sure that is not that case though.

im thinking something with the turbo. but even fully blown ones with tons of shaft play still make more than 1psi.

and if the wastegate flap door is "broke" or just stays open you wouldnt really make any boost, since all most of the exhaust would go down the downpipe.

D. Joy · 03-27-2011, 09:09 AM

Alright, it's an Sr GT25.
A little more about the engine itself; it's been rebuilt with supertech pistons, eagle rods, acl bearings etc etc. Runs with megasquirt, sr370cc injectors, wideband o2 sensor and walbrofuel pump to deliver the goods.

Bear with me since this is my first time with a turbo car...

No maf and no bov. When we were checking for vac leaks we swapped out the hot pipe for one without a bov to see if that would help and that's how it is now.

I'm going to post a pic tomorrow of the turbo and anything else you guys might want to see if you give me a headsup. It's out of the car now and I think I might actually be missing some nuts where the manifold bolts to the turbo, at least that's what it looks like at first glance...

*blksylv* · 03-27-2011, 09:18 AM

if its leaking bw the turbo and the manifold thats prolly the culprit, had the same thing on my sr , first it sounded like a lazer gun when it started to boost then it stopped boosting at all, replaced the gasket and it was back to normal

D. Joy · 03-27-2011, 03:33 PM

Sweettt. That'd be great if its only that manifold gasket, but I'm still worried about the oil I saw in the piping. It wasn't a whole lot, but its there and it's bugging me. Is a rebuild instore? I don't mind, its not too expensive, especially on such a baby turbo, I just want to hear it from the more experienced.

Thanks a lot dudes

D. Joy · 03-27-2011, 03:48 PM

This is the manifold to wastegate, I feel like nuts are missing, it's not like you can pull the manifold off so I guess they're just studs? Enlighten me please.

Sileighty_85 · 03-27-2011, 04:15 PM

So whats metering you air if you have no MAFS?

D. Joy · 03-27-2011, 11:50 PM

Mega squirt is doing the work of the maf

Sileighty_85 · 03-28-2011, 10:27 AM

Quote:

Originally Posted by D. Joy

Mega squirt is doing the work of the maf

I see, but how does mega squirt know how much air is entering the engine?
Is it Guessing?

Does it use a MAP?

(Sorry not to familiar with MS)

D. Joy · 03-28-2011, 10:45 AM

All good, I'm learning too as I didn't build the car. In the back of the Megasquirt there is an opening where an air line runs into and the MS calculates the engine load. If I remove this little line the car will crap out as if you were to remove the MAF on any other car. MS is pretty cool shit, but the r e a l workings of it are just fairy dust to me.

Gunna ask again, should I buy a rebuild for this turbo? There really shouldn't be any oil in these pipes correct? A turbo that's spitting oil, even a little, doesn't seem like something you just brush off you shoulders haha
Would leaky seals also possibly cause the low boost situation?

mattsil80wis · 03-28-2011, 11:08 AM

could the MS but limiting the boost level?

D. Joy · 03-28-2011, 12:00 PM

I don't think so, I don't see how it could really, but I really don't know enough about it

...

D. Joy · 03-29-2011, 06:11 PM

I was fiddling around with my turbo off the car today and noticed something with the waste-gate flap...
With the actuator arm attached, the waste-gate flap seems a little loose. It's definitely sitting against the turbine housing, but very lightly. I can take a flat head and actually slip it under the flap a tad or I can take my finger and spin the flap. It's barely any play, but I'm wondering if this might be my problem causing the pressure to escape. Should the gate be seated very firmly against the housing?

Sileighty_85 · 03-29-2011, 07:07 PM

youp there should be a bit of pressure holding it against the turbo.

Tighten the flap down if you can

03-26-2011, 10:57 AM	#1
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	Low boost Just recently bought an s13 with a Ka-T setup. Was garaged for about a year before I came along and supposedly was working fine when it was parked. Went to drive away and we find out its not building boost, maybe about a 1lb. Un-did and re-attached all the intercooler piping and couplers to make sure there were no vacuum leaks and still ended up not building boost. Anyways, got the car home and took turbo setup apart and found some oil in my hot pipe and couplers. Does that mean I need to replace the seals in the turbo? There's no shaft play so I don't think its blown... Would the damaged seals be reason for no boost? Can anyone point me in the right direction? thanks.

03-27-2011, 04:07 AM	#4
Drifting-pedobear Zilvia Addict Join Date: Jan 2009 Location: seattle, wa Age: 30 Posts: 937 Trader Rating: (11) Feedback Score: 11 reviews	wouldnt be the wastegate, you would have the opposite issue, too much boost. my money is on the turbo being lop. is it a s13 sr turbo? more details about the motor would help... __________________ RIGHTWHEELDRIVE.com

03-27-2011, 04:15 PM	#10
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	So whats metering you air if you have no MAFS? __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

03-29-2011, 07:07 PM	#17
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	youp there should be a bit of pressure holding it against the turbo. Tighten the flap down if you can __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

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03-26-2011, 11:22 AM	#2
hartig Zilvia Member Join Date: Mar 2010 Location: western ma Age: 31 Posts: 268 Trader Rating: (4) Feedback Score: 4 reviews	this might sound dumb.. but did you check the wastegate/ wastegate hose?

03-26-2011, 03:21 PM	#3
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	Yeah, but I don't know exactly what to look for, except for a possible leak in the hose and that the waste gate can open and close. Both seem okay, no leak and the gate moves by hand with a little effort.

03-27-2011, 08:27 AM	#5
titangts Zilvia Addict Join Date: Jul 2009 Location: charlotte Posts: 666 Trader Rating: (10) Feedback Score: 10 reviews	are you running a blow through set up like maf before the TB? or standard before the turbo..if blow through make sure your bov isnt stuck open lol. im sure that is not that case though. im thinking something with the turbo. but even fully blown ones with tons of shaft play still make more than 1psi. and if the wastegate flap door is "broke" or just stays open you wouldnt really make any boost, since all most of the exhaust would go down the downpipe.

03-27-2011, 09:09 AM	#6
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	Alright, it's an Sr GT25. A little more about the engine itself; it's been rebuilt with supertech pistons, eagle rods, acl bearings etc etc. Runs with megasquirt, sr370cc injectors, wideband o2 sensor and walbrofuel pump to deliver the goods. Bear with me since this is my first time with a turbo car... No maf and no bov. When we were checking for vac leaks we swapped out the hot pipe for one without a bov to see if that would help and that's how it is now. I'm going to post a pic tomorrow of the turbo and anything else you guys might want to see if you give me a headsup. It's out of the car now and I think I might actually be missing some nuts where the manifold bolts to the turbo, at least that's what it looks like at first glance...

03-27-2011, 03:33 PM	#8
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	Sweettt. That'd be great if its only that manifold gasket, but I'm still worried about the oil I saw in the piping. It wasn't a whole lot, but its there and it's bugging me. Is a rebuild instore? I don't mind, its not too expensive, especially on such a baby turbo, I just want to hear it from the more experienced. Thanks a lot dudes

03-27-2011, 03:48 PM	#9
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	This is the manifold to wastegate, I feel like nuts are missing, it's not like you can pull the manifold off so I guess they're just studs? Enlighten me please.

03-27-2011, 11:50 PM	#11
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	Mega squirt is doing the work of the maf

03-28-2011, 10:45 AM	#13
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	All good, I'm learning too as I didn't build the car. In the back of the Megasquirt there is an opening where an air line runs into and the MS calculates the engine load. If I remove this little line the car will crap out as if you were to remove the MAF on any other car. MS is pretty cool shit, but the r e a l workings of it are just fairy dust to me. Gunna ask again, should I buy a rebuild for this turbo? There really shouldn't be any oil in these pipes correct? A turbo that's spitting oil, even a little, doesn't seem like something you just brush off you shoulders haha Would leaky seals also possibly cause the low boost situation?

03-28-2011, 11:08 AM	#14
mattsil80wis Zilvia Junkie Join Date: Jan 2008 Location: nj Age: 34 Posts: 391 Trader Rating: (6) Feedback Score: 6 reviews	could the MS but limiting the boost level?

03-28-2011, 12:00 PM	#15
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	I don't think so, I don't see how it could really, but I really don't know enough about it ...

03-29-2011, 06:11 PM	#16
D. Joy Join Date: Apr 2010 Location: po-town Age: 32 Posts: 34 Trader Rating: (0) Feedback Score: 0 reviews	I was fiddling around with my turbo off the car today and noticed something with the waste-gate flap... With the actuator arm attached, the waste-gate flap seems a little loose. It's definitely sitting against the turbine housing, but very lightly. I can take a flat head and actually slip it under the flap a tad or I can take my finger and spin the flap. It's barely any play, but I'm wondering if this might be my problem causing the pressure to escape. Should the gate be seated very firmly against the housing?