Jump to content
SAU Community

Recommended Posts

I've got my turbotech boost controller set to 10psi, and it worked great for about a week. Now when accelerating past 4,500rpm boost drops noticeably to about 5psi (although the gauge shows 5psi it doesn't even feel like it's making that much boost). It's a really noticeable drop off in power.

I took it to the mechanics the other week and wouldn't you know it, the car worked fine when I was there.. but the problem is back now. Any suggestions of where to look? Will it just be a leak in the vacuum line?

Problems driving me nuts.. boost seems to work and pull fine prior to hitting those higher revs, like the additional pressure is causing a leak???

Link to comment
https://www.sau.com.au/forums/topic/188252-losing-boost-after-4500-rpm/
Share on other sites

When I removed my plenum to inlet manifold gasket I noticed it had been leaking.

When refitting inlet manifold/plenum/throttle body gaskets I gave them a spray with Hylomar just incase.

Using Hylomar also helps should you have to pull it apart again; it prevents gaskets ripping etc so you can save a few $$ and reuse. :(

When I removed my plenum to inlet manifold gasket I noticed it had been leaking.

When refitting inlet manifold/plenum/throttle body gaskets I gave them a spray with Hylomar just incase.

Using Hylomar also helps should you have to pull it apart again; it prevents gaskets ripping etc so you can save a few $$ and reuse. :(

could you haer a sucking sound coming from the plenum when it was leaking.

could you haer a sucking sound coming from the plenum when it was leaking.

I can hear a sucking or hissing type sound coming from my plenum at the moment. Didn't know what it was though, just thought it may have been normal. Guess my plenum is leaking then?

Edited by Simmo1985

Would a leaking plenum cause any other problems? Just trying to figure out if that is in fact the problem, because the car drives perfectly normal otherwise.

Edited by Simmo1985
could you haer a sucking sound coming from the plenum when it was leaking.

No strange sucking noises apart from the usual idle sssshhh noise :)

I think mine was only leaking on boost as it didn't cause any strange idle issues or afm readings.

i got this same problem, i hear a loud hissing like noise come from the plenum at high boost and notice my PSI drop from 20 to 15.. I still haven't got around to pulling the plenum apart and changing the gasket, but i'm pretty sure thats the problem..

  • 3 months later...

I think I have a similar problem. Had it tuned running 18psi no worries but after a week of driving it doesn't seem to hold boost. After 6000rpm the boost drops from 18psi to about 5psi. I can't hear any strange noises though..

I dont think its the inlet sucking closed as I placed a metal pipe in part of it. It looks a little weepy round the plenum gasket. Hopefully thats it..

ANYone got the part no. for R33gtst?

Edited by benl1981

The mechanic reckons I should just change the gasket without even running it on the dyno. They reckon theyve seen a lot of this on the rb25s. It isn't always that easy to hear apparently - and under load there is so much air floating around there with the fan going etc..

Will have a bit more of a check myself..

Nissan want $85 for one! There was a little oil residue around the join. We cleaned this off but there isn't really much coming back. Might run it up onto boost a few times and check again. I did a few 0-100km/h runs the other day which may have blown it apart..

Edited by benl1981

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • A few small updates since the previous post and lessons. I decided to do a little interior light upgrade on the 110. I quite like the iilumo items, even if they're a bit of a premium over other brands. You'll also note the Stedi Fogs, that will go into the S15 fog lights as I needed to match the bulbs since I got the new ones earlier. I hope they fit as the body is quite a bit longer than your normal bulb.  Annoyingly, I managed to trip the fuse, which normally wouldn't be an issue until I located the fuse. I can't say I've ever come across this. I had lucked out that someone nearby had a spare, but oddly enough Toyota dealerships seem to keep this in stock. I ordered some to keep in my stash and as luck would have it, someone else nearby tripped the same fuse so I passed on the favour.  I also did a little service on the 110 ahead of some additional work coming up. It's been annoying that Goleby's stopped carrying this particular HKS filter for the 110, so now I need to keep them on order from Japan. I also took the opportunity to install a bash plate and number plate riser. The plate riser is such a cheap but nice fix to help really tidy up the car. I'm tempted to now also replace my headlights, on this car. Both items were from Project Aero.    I also needed to replace the rear tyres on the 110, and after trying to get it aligned learnt that I need to replace some bushes in the front end, so that's next.  Closing out this update with a nicer picture as always! 
    • Yeah mate, never miss it.
    • Any going to watch World Time Attack at SMSP this year?
    • Appreciate the correction on the "ground", that will make a huge difference to looking at this. That makes complete sense about AF70/AF71 which is what I had come down to being the issue, one of these. I'll have another look in the ignition wiring when I get a chance next week. I'll also make up a jumper wire for running that AF73 test.  ECU is fine, relay itself is fine, pump harness is fine and the pump itself is fine. I am going to upgrade the Walbro 255 anyway with a DW300 I have since I need to replace the fuel sender and I'm going to upgrade the FPR with my chasebays kit ready for new plenum/injectors/dbw, but I'll get this working first. That's why this is so frustrating. 
×
×
  • Create New...