No boost, help!

[ColinR33]

Having some issues with my GTR. Startedout as a loss of boost in 3rd gear, then progressed to second then to no boost at all in first over the course of a day. Idle is somewhat uneven now as well. I have searched for possible causes and have done a number of checks:
Coils good
Plugs good
No turbine bits in the downpipe/cat (R34 N1 turbos, so steel wheel but checked anyway)
No vacuum leak
Can't find any loose hoses around the ic/intake plenum, but gonna go back with soapy water to checkfor bubbling.
No MAF's to worry about, running Vipec
Not blowing smoke other than slight bit at startup
Boost controller lines seem OK

The only things I did recently was install a new steering wheel and an oil catch can vented to atmosphere. Caught no oil (Mines cam cover baffles doing their job - also no oil in BOV discharge like before) and I reconnected old hoses. Could that have screwed things up somehow?

Anything else I should check? Wastgate actuators? I'd have to take the dumps and downpipe off for that right?

Thanks!

[ColinR33]

Forgot to mention, I just changed the fuel filter as well. Noticed that when it is running, air flow thru the intakes appears to shuffle between them at idle, 2-3 second intervals, and i have the divided intake pipe! Also seems to be a sighing sound after the engine shuts off, like air escaping but can'tseem to pinpoint it.

[NismoS-tune]

Sadly, Most of the things you've checked wouldn't cause loss of boost unless you had other signs, like black smoke, big bogging/stuttering.

Have you checked your wastegates? Are they still tight. Disconnect and plug the boost control line going to the wastegates swing valves and see if you build some boost then, be careful though you should only see boost as high as your springs are rated at (I don't use boost controllers, all good). Plugged filters?

Post what you find. When was your last compression test?

You're running Honeywell Garrett mexican/texan turbos right? -5?

[ColinR33]

Thanks, i will give that a try tomorrow night. Car does bog when I give it gas. Can't remember if/ when i did last compression test lol, was thinking i should get a tester and do it for peace of mind.

[ColinR33]

Oh, and turbos are GT2560R (707160-9).

[Skym]

The only things I did recently was install a new steering wheel and an oil catch can vented to atmosphere. Caught no oil (Mines cam cover baffles doing their job - also no oil in BOV discharge like before) and I reconnected old hoses. Could that have screwed things up somehow?

You should retune engine after fitting atmosphere vented catchcan.

Forgot to mention, I just changed the fuel filter as well. Noticed that when it is running, air flow thru the intakes appears to shuffle between them at idle, 2-3 second intervals, and i have the divided intake pipe! Also seems to be a sighing sound after the engine shuts off, like air escaping but can'tseem to pinpoint it.

Shuffling can be due to internal wastegate malfunction, did you block the PCV recirc holes in piping before turbo's???

If not, that could explain the sighing sound, no boost (air escaping before reaching turbo's).

[ColinR33]

You should retune engine after fitting atmosphere vented catchcan.

Shuffling can be due to internal wastegate malfunction, did you block the PCV recirc holes in piping before turbo's???

If not, that could explain the sighing sound, no boost (air escaping before reaching turbo's).

Talked to Cam at Lightspeed, he said the atmospheric catch can wouldn't affect the tune and that the shuffling between intakes at idle was normal. Yes, did block the PCV recirc holes. But that is all moot now. Took the front bumper off and got out the soapy water and checked all the ic lines - nothing. Then as i was manipulating the throttle linkage i felt a stream of air blowing on my wrist, and fml, the boost gauge sensor line must have gotten caught in the throttle linkage and pinched! Small hole at first and then grew, explains the gradual loss of boost. Boy do I feel like a dumbass lol. Shoulda checked the simple stuff first! Oh well, $2 fix to replace the sensor line. Chalk it up as experience.

[NismoS-tune]

nice! super simple.

Disconnecting the wastegate hoses would have pointed towards a boost control issue right away! Hope you didn't spend too much time doing other stuff or calling everyone hahaha.

[louis110]

Glad it all worked out for you Colin! It could've been extremely frustrating to diagnose.

[ColinR33]

Yeah, very happy, have a temporary hose connector in until I can get some silicon vacuum hose and replace it all, its getting pretty brittle. Did dissassemble the exhaust to check the cat and pulled the front bumper to better see the ic lines for soap testing, so an hour or so to put it all back together.