SR20DET vacuum line woes - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

5t341tH · 06-25-2019, 03:09 PM

Hey guys I need some help. I have a blacktop Sr20det that I am swapping into my Datsun pickup. I am currently dealing with the vacuum/boost lines. On the throttle body, there are two upper nipples. I have the left one going to the FPR and tee’d with my boost gauge. The right one goes to my BoV. It seems I only have vacuum at those ports. My bov will stay wide open during idle and when I rev it, it closes. My boost gauge will only read in vacuum and never see boost. What can be causing the vacuum only issue? Thanks

jedi03 · 06-26-2019, 08:11 AM

are you looking for boost with no load? it wont pickup much while you are sitting there...the engine is in vacuum when idling and your BOV is designed to open when off throttle...sounds like your spring may be to soft if its opening just sitting there tho as its supposed to open whenever you let off the gas...what boost are you getting when you have a load and do you have a way to test the guage as i have seen many fail over the years...

5t341tH · 06-26-2019, 04:00 PM

This is a new swap so all parts I have are new. At idle, my tail bov is wide open. Also the same when I bolt on the Hks. I’ve driven around and it still shows no boost. I will only see vacuum and 0psi. My gauge is innovate motor sports scg1. I believe it used a map sensor. I have that tee’d into the fpr line

jedi03 · 06-27-2019, 08:22 AM

http://www.frozenboost.com/bov-a-bov.html what are your compression numbers? secondly are you hearing the turbo spool while you accelerate or does it just barely function?

*TheRealSy90* · 06-27-2019, 02:45 PM

There are vacuum only ports and vacuum/boost ports on the sr20 throttle body and intake manifold.

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5t341tH · 06-29-2019, 05:30 PM

How can I tell if my turbo is spooling? This is a brand new s15 t28. When I first started it up after my swap, I could hear it spool. But now I don’t hear anything. What should I check?

Kingtal0n · 07-01-2019, 12:07 AM

1. pressure test the plumbing from the compressor cover through the engine
2. get a vacuum/boost gauge

5t341tH · 07-02-2019, 03:46 PM

Nvm it is working. Just strange that during low speed driving in the parking lot, it never shows boost. Only when I drove it on the streets did I hit boost. 7psi is the norm with just the wastegate correct? I still question why my Tial BoV stays wide open when idling? It causes the engine to idle like crap and want to die.

06-25-2019, 03:09 PM	#1
5t341tH Post Whore! Join Date: Jun 2006 Location: socal (Huntington Beach) Age: 33 Posts: 2,776 Trader Rating: (14) Feedback Score: 14 reviews	SR20DET vacuum line woes Hey guys I need some help. I have a blacktop Sr20det that I am swapping into my Datsun pickup. I am currently dealing with the vacuum/boost lines. On the throttle body, there are two upper nipples. I have the left one going to the FPR and tee’d with my boost gauge. The right one goes to my BoV. It seems I only have vacuum at those ports. My bov will stay wide open during idle and when I rev it, it closes. My boost gauge will only read in vacuum and never see boost. What can be causing the vacuum only issue? Thanks __________________ lexus baby

06-26-2019, 04:00 PM	#3
5t341tH Post Whore! Join Date: Jun 2006 Location: socal (Huntington Beach) Age: 33 Posts: 2,776 Trader Rating: (14) Feedback Score: 14 reviews	This is a new swap so all parts I have are new. At idle, my tail bov is wide open. Also the same when I bolt on the Hks. I’ve driven around and it still shows no boost. I will only see vacuum and 0psi. My gauge is innovate motor sports scg1. I believe it used a map sensor. I have that tee’d into the fpr line __________________ lexus baby

06-29-2019, 05:30 PM	#6
5t341tH Post Whore! Join Date: Jun 2006 Location: socal (Huntington Beach) Age: 33 Posts: 2,776 Trader Rating: (14) Feedback Score: 14 reviews	How can I tell if my turbo is spooling? This is a brand new s15 t28. When I first started it up after my swap, I could hear it spool. But now I don’t hear anything. What should I check? __________________ lexus baby

07-02-2019, 03:46 PM	#8
5t341tH Post Whore! Join Date: Jun 2006 Location: socal (Huntington Beach) Age: 33 Posts: 2,776 Trader Rating: (14) Feedback Score: 14 reviews	Nvm it is working. Just strange that during low speed driving in the parking lot, it never shows boost. Only when I drove it on the streets did I hit boost. 7psi is the norm with just the wastegate correct? I still question why my Tial BoV stays wide open when idling? It causes the engine to idle like crap and want to die. __________________ lexus baby

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06-26-2019, 08:11 AM	#2
jedi03 Nissanaholic! Join Date: Jul 2008 Location: albuquerque Posts: 1,786 Trader Rating: (8) Feedback Score: 8 reviews	are you looking for boost with no load? it wont pickup much while you are sitting there...the engine is in vacuum when idling and your BOV is designed to open when off throttle...sounds like your spring may be to soft if its opening just sitting there tho as its supposed to open whenever you let off the gas...what boost are you getting when you have a load and do you have a way to test the guage as i have seen many fail over the years...

06-27-2019, 08:22 AM	#4
jedi03 Nissanaholic! Join Date: Jul 2008 Location: albuquerque Posts: 1,786 Trader Rating: (8) Feedback Score: 8 reviews	http://www.frozenboost.com/bov-a-bov.html what are your compression numbers? secondly are you hearing the turbo spool while you accelerate or does it just barely function?

07-01-2019, 12:07 AM	#7
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,649 Trader Rating: (17) Feedback Score: 17 reviews	1. pressure test the plumbing from the compressor cover through the engine 2. get a vacuum/boost gauge