why is my boost at 0 psi flat? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

dwadia · 10-06-2006, 04:23 PM

I have an s14 with a modded sr engine, and about a week ago one of the hoses to the IC blew off while driving. When this happened the car wouldn't rev above 2k or 2.5k rpm (i forget which one), so i just chugged it along for 15 minutes until i got home. I turned it off and later turned it back on (still without the hose connected), and the car then revved freely, just without the turbo boosting. I assumed the computer somehow accounted for the separated hose and bypassed the turbo completely.

Here's the problem: i replaced all the couplers and flimsy clamps with t-bolts over the past week. I started it up today, with everything all tight. No boost. I thought maybe the computer still "thought" the hose was separated so i disconnected the battery and reconnected it to see if that would somehow clear any memory, but still no boost. The motor revs fine, but i have no boost and no vacum. Can someone please tell me what the problem could be and how to solve it? Thanks.

trsilvias13 · 10-06-2006, 04:30 PM

are you revving this at stand still? if so go drive it and see if you read boost.

DoriftoPnoy · 10-06-2006, 05:00 PM

uh.... is this still a stock turbo? mine was doin this too. turned out the actuator arm fell off the wastegate and it was open all the time; hence no boost. might wanna check that out.

dwadia · 10-06-2006, 05:11 PM

Thanks both of you for your replies...

1) I tried it both at a standstill and driving, revved it all the way through 3rd gear. Same results. And it's not a boost gauge problem - i can feel that it's not making boost. Plus i have 2 "boost gauges," one on my turbo timer and another on my boost controller, and they're both at 0.

2) No, not the stock turbo. I didn't think the list of mods would be too important for this problem, but maybe it is relevant, so here it is:
SR20DET Redtop
Peak Boost manifold, down pipe, and dump tube
GT3071R
HKS Type-S intercooler
GReddy intake manifold
Power Enterprise head gasket
JWT S4 cams
HKS cam gears
GReddy valve springs
HKS SSQV blow off valve
Z32 MAF
Nismo 740cc injectors
Nismo adjustable fuel pressure regulator
Fuel pressure gauge
Dyno Rom Tune - Enthalpy
JWT Z32 pop charger
TAil 38mm waste gate

Thanks again.

PantherRacer · 10-06-2006, 05:49 PM

This happened to me also,hose blew off, clamped it back still no boost. It turned out to be a boost leak from a hose that wasn't clamped down properly. Check ALL hoses and connections, have someone rev the car while you watch the hoses or vice versa. It might blow out a bit while under boost then slip back in when the pressure's gone.

dwadia · 10-06-2006, 06:03 PM

I will do that as it definitely can't hurt, but i did just replace all the clamps and many couplers all the way from the turbo to the throttle body. Every connection was separated and then put back together. If there was a situation as described in the previous post, wouldn't i at least get a vacum reading at idle?

nrg · 10-06-2006, 07:07 PM

make sure the vac line to the boost gauge didn't some how pop off too.

dwadia · 10-07-2006, 09:25 PM

I found the problem and just wanted to thank everyone for their responses. There was a vacuum line which came loose somehow from the underside of the throttle body. This line went to a tee, which i believe was connected to both my boost controller and turbo timer/boost gauge, thus making both of them read at 0 psi. Thanks again.

10-06-2006, 04:23 PM	#1
dwadia Zilvia Junkie Join Date: Sep 2006 Location: NJ Age: 42 Posts: 302 Trader Rating: (2) Feedback Score: 2 reviews	why is my boost at 0 psi flat? I have an s14 with a modded sr engine, and about a week ago one of the hoses to the IC blew off while driving. When this happened the car wouldn't rev above 2k or 2.5k rpm (i forget which one), so i just chugged it along for 15 minutes until i got home. I turned it off and later turned it back on (still without the hose connected), and the car then revved freely, just without the turbo boosting. I assumed the computer somehow accounted for the separated hose and bypassed the turbo completely. Here's the problem: i replaced all the couplers and flimsy clamps with t-bolts over the past week. I started it up today, with everything all tight. No boost. I thought maybe the computer still "thought" the hose was separated so i disconnected the battery and reconnected it to see if that would somehow clear any memory, but still no boost. The motor revs fine, but i have no boost and no vacum. Can someone please tell me what the problem could be and how to solve it? Thanks.

10-06-2006, 05:00 PM	#3
DoriftoPnoy Zilvia Addict Join Date: Apr 2005 Location: SoCal 818 Posts: 715 Trader Rating: (2) Feedback Score: 2 reviews	uh.... is this still a stock turbo? mine was doin this too. turned out the actuator arm fell off the wastegate and it was open all the time; hence no boost. might wanna check that out. __________________

10-06-2006, 07:07 PM	#7
nrg Zilvia FREAK! Join Date: Mar 2004 Location: CA Age: 40 Posts: 1,571 Trader Rating: (1) Feedback Score: 1 reviews	make sure the vac line to the boost gauge didn't some how pop off too. __________________ driftingisgay.com

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10-06-2006, 04:30 PM	#2
trsilvias13 Nissanaholic! Join Date: Nov 2001 Posts: 1,995 Trader Rating: (5) Feedback Score: 5 reviews	are you revving this at stand still? if so go drive it and see if you read boost.

10-06-2006, 05:11 PM	#4
dwadia Zilvia Junkie Join Date: Sep 2006 Location: NJ Age: 42 Posts: 302 Trader Rating: (2) Feedback Score: 2 reviews	Thanks both of you for your replies... 1) I tried it both at a standstill and driving, revved it all the way through 3rd gear. Same results. And it's not a boost gauge problem - i can feel that it's not making boost. Plus i have 2 "boost gauges," one on my turbo timer and another on my boost controller, and they're both at 0. 2) No, not the stock turbo. I didn't think the list of mods would be too important for this problem, but maybe it is relevant, so here it is: SR20DET Redtop Peak Boost manifold, down pipe, and dump tube GT3071R HKS Type-S intercooler GReddy intake manifold Power Enterprise head gasket JWT S4 cams HKS cam gears GReddy valve springs HKS SSQV blow off valve Z32 MAF Nismo 740cc injectors Nismo adjustable fuel pressure regulator Fuel pressure gauge Dyno Rom Tune - Enthalpy JWT Z32 pop charger TAil 38mm waste gate Thanks again.

10-06-2006, 05:49 PM	#5
PantherRacer Join Date: Sep 2006 Location: Nassau, Bahamas Age: 38 Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	This happened to me also,hose blew off, clamped it back still no boost. It turned out to be a boost leak from a hose that wasn't clamped down properly. Check ALL hoses and connections, have someone rev the car while you watch the hoses or vice versa. It might blow out a bit while under boost then slip back in when the pressure's gone.

10-06-2006, 06:03 PM	#6
dwadia Zilvia Junkie Join Date: Sep 2006 Location: NJ Age: 42 Posts: 302 Trader Rating: (2) Feedback Score: 2 reviews	I will do that as it definitely can't hurt, but i did just replace all the clamps and many couplers all the way from the turbo to the throttle body. Every connection was separated and then put back together. If there was a situation as described in the previous post, wouldn't i at least get a vacum reading at idle?

10-07-2006, 09:25 PM	#8
dwadia Zilvia Junkie Join Date: Sep 2006 Location: NJ Age: 42 Posts: 302 Trader Rating: (2) Feedback Score: 2 reviews	I found the problem and just wanted to thank everyone for their responses. There was a vacuum line which came loose somehow from the underside of the throttle body. This line went to a tee, which i believe was connected to both my boost controller and turbo timer/boost gauge, thus making both of them read at 0 psi. Thanks again.