I have an 86 300zx turbo. I'm having issues with my boost. When I'm at higher rmps it'll boost hard and pull great but every time I shift it falls on its face and takes a bit to build its boost back up, terrible situation for long pulls. I'm not sure what could be causing this, I was thinkin my wastegate out of adjustment or my blow off releasing too much pressure, any ideas would be great! Thanks!

 

Welcome to ZDriver!

Pick up a freebie factory service manual at XenonZ31 Reference along with the other docs. Your FSM has a lot of tune-up, inspection and repair pages that could help. Check 'em out.

Sounds like you're getting the boost you expect (did you add a manual boost control and a new gauge? Great mod for the '86T and not expensive, lotsa write-ups on it. Just don't boost too high or you blow seals/gaskets) but your between-shift RPMs are dropping off too fast. Never had that prob but somebody here has and knows what probably causes it. Doesn't sound like a major repair to me). RPMs should drop a bit but a quick shift catches 'em still high enough..)

Thanks and welcome again!

 

I do have manual boost adjust, i'm only running 10psi due to its a recent purchase and I don't know what the guy has done. I also have aftermarket gauge. I just can't figure out why its falling on its face for so long between gears. I have a small manifold leak I'm fixing this spring but it isn't bad enough to lose that much boost.

 

Air reg has a couple of solenoids you can check with a multimeter. Make sure they are working. Also, what RPM do you warm-idle at? 600-900?

 

I usually warm idle between 700 - 800 rpm, slight fluctuation on colder days. Do you know the solenoid specs or would all that be listed in the manual mentioned above?

 

For the air reg check out diag EF&EC-3 in your manual. The air reg is hanging out on the right side of your injector plenum. The solenoids are the idle-up one and the fast-idle-control (FICD) See the diagram to locate.

No, wait. That's for my 86NA. You quick-check if they are working by removing them from the reg, disconnect them, apply your volts to one end, ground the other and listen/feel for the click. You can feel it working. If nothing moves, it's dead. Gotta be replaced. I had to buy a whole recycled regulator to get them - but there may be another way now. They are like $5 parts - if you need them. Check that out for starters.

But for your turbo (VG30ET) the diagrams show something else. Check out EF&EC 7. Has a different air reg. Fast idle is there but with air control AAC valve. Check it out anyway. Maybe only one solenoid there - and there's a couple of other valves elsewhere. Looks like 2 or 3 valves in controlling air for combustion - judging from the diag. I would go out and check under the hood now - but it's nighttime and raining here. Try to locate those other valves for now. We can figure out how to check them. Could be a buncha stuff...

I had a sticky throttle cable once but that caused the opposite problem: too-high RPMs between gears. Check your throttle to see if it could be acting weird... Lemme think.