Neu_maddox

I'm pretty much a silent user on this site, I'm here daily reading up and you guys all have helped me sort out alot of my problems, I searched up and down but couldn't find a similar problem to mine, now to tha problem, I've Rebuilt the AFM, Tested all my fuel pressure and injectors, fuel pump turns on (I can hear it), absolutely no vacuum leaks, turbo bolts are all tight, fresh fuel and air filter, Cylinder compression test came back 120 on every cylinder, but no matter what I do the turbo wont spool past 2-3 PSI and just bogs the engine down, tha only thing I could think of is the cat is plugged up, replacing it with a straight pipe tomorrow morning at the shop I work at and hopefully that solves the problem, the only thing other then that is the turbo itself going out. I'm gonna replace the oxy sensor tomorrow when I weld in that pipe so I have my fingers crossed. The car sat for a good eight years before I got it so I had to replace alot when I got it but its steadily gotten worse since, I had it up on the lift when I measured the cat and smacked the cat a few times to see if it was making a rattling noise and then as soon as I drove off i gained around 1 psi leaving the lot. I'm gonna get rid of the cat either way tomorrow but in case that doesn't solve this issue (fingers crossed) I wanna know where to go next. I'm just stumped. I've read the FSM pretty thoroughly but that only goes so far. Anyone else had a similar problem with their turbo or am I just missing something obvious? thanks

skib

damn, that sucks. your turbo should have 0 lag from like 3 grand. mine would jump strait to 10lbs soon as you lay on the loud petal

hoov100

Always start off with the basics man, if it's not building boost past a certain point, check your wastegate flapper, make sure its moves freely and is not stuck. If it's not stuck and moves freely, check your wastegate actuator and the vacuum lines going to it.

snwbrderphat540

if that doesnt work, take off the AFM boot from the turbo and check for shaft play, usually the turbo will sound louder though when it is going out. but yeah stick your finger on the shaft of the compressor and try to wobble it around. should barely move. if it shakes a decent amount that could be your problem. also try to spin the turbine by finger, it should glide "ok" but not feel rough or have resistance to trying to spin it.

FricFrac

Is it OK to spin the turbo by hand without oil or is there enough residue that its OK?

skib

yes its fine.

on your car its spinning around 10,000-15,000 RPM so spinning it with your fingers is nothing to your turbo lol

snwbrderphat540

dude what? its spinning up to and over 100,000 RPM when in full spool....

skib

typo.

hoov100

electromotive sells turbo tachs, which go to 400k RPM.

Neu_maddox

Ok, I'm off tomorrow so I'll take it to my work an check the actuator and for shaft play. I also got the straight pipe fabricated yesterday so I might as well put it in place of the Cat. I also smelled gas the other day so started checking and my #1 injector is leaking a little bit from around the top where it clamps, is it pressed into the injector or just seated inside of it where I can replace it with new fuel line or will I have to get a whole new injector? I wrapped it in electrical tape and put a new clamp up higher on the fuel line and its not leaking anymore for right now, noticed an immediate gain in acceleration so I figure it must have been losing some fuel pressure from right there, I've been disappointed in the performance lately but I haven't been pushing it to hard because I wanna make sure everythings bulletproof before I see what it can really do and start adding things like an electronic boost controller and IC. It's worth the work though because around here most people have no idea what it is and the people that do wanna buy it outright or give me a thirty minute lecture on what they would do if they had it, and here in wichita EVERYONE wants me to v8 it, not happening unless I blow this motor up badly, thanks for the speedy reply too this forum is the best

Neu_maddox

Replaced the cat with the straight through pipe today, huge difference in power and acceleration to the point i know now I need to put new springs and struts in the rear, already have some in mind so thats not a bad thing. Turbo spooling up about 1 PSI higher but still not going all the way up to 7 lbs, I know you mentioned the wastegate might be sticking, this is a noob question but where is that on the turbo, is it near the actuator or do I need to pull something off the turbo itself? all the vaccum lines seem solid and aren't leaking, and the afm plug, what side of the turbo is that on so I can check shaft play? Really starting to enjoy driving the z again but I know I still have alot of work to do before its trackready

NismoPick

Picture from the "google" machine:



I also suggest reading these books:

hoov100

screw those two out dates books, go to garrett's website and read up in their tech area, they have it labeled from noob to advanced.

snwbrderphat540

lol i said take the intake off the turbo and check for shaft play... the shaft only sticks out on two ends of the turbo. so unless you want to pull the exhaust off the car....

i take it you are new to turbos huh? also you SURE your boost gauge is working properly? no leaks in it anywhere?

Neu_maddox

I didn't equate AFM boot to intake, an yeah not new to cars in general but forced induction is pretty new to me, I've read alot about it but I haven't had enough hands on to be completely comfortable with it. Just like anything else though I've worked on, once I get a chance to tear it apart I'll be cool. I work in an autoshop though so on the rare occasion I run into something that confuses me I just ask another mechanic there. Their all Government Motors guys though so as far as the turbo goes I'm on my own, only other guy that has knowledge about that drives a turbo thunderbird coupe and hes not exactly a forced induction expert. Anyway thanks for the advice I'll check that after work tomorrow, hopefully its a vac-line leak or something minor and not a shitton of shaft play.

Neu_maddox

I got to thinking , would the boost gauge be showing it shoot down to -7 if it wasn't working properly?

hoov100

go to autozone and buy a cheap mechanical in line fuel pressure gauge (for a carb), hook it up to a clean vacuum source, as nearest to the turbo as you can get and while driving, watch it, if it hits 7psi, its the gauge, if it only hits 2psi, you either didn't hook up the gauge right, ot its time to start diagnosing things.

snwbrderphat540

-7 psi? i have no idea if that is normal haha. im used to inHg for VAC readings which is typically about -20... anyone good at conversions? lol. also this was never asked, stock boost gauge? or aftermarket?

snwbrderphat540

-7 x 2.04 = 14.something... so sounds a little low.... unless you have an aftermarket cam.

NismoPick

Kids...

VACUUM IS NOT MEASURED IN PSI.

The stock 280ZX Turbo boost gauge reads mmHg of vacuum. -7mmHg DOES NOT EQUAL -7PSI

The needle should be smack dab at 0 if the key is ON and the motor not running. If it's not, it needs to be calibrated by the adjuster in the glove box.

Click if you want to do the simple math: http://www.anver.com/document/compan.../pressure.html

hoov100

I hope not, if it is, I've been doing things very wrong.

snwbrderphat540

hence why i asked if this was a stock boost gauge or not, and since i don't have an S130 nor the stock boost gauge out of one, and not knowing if he had an aftermarket one or not, i presumed he POSSIBLY knew what he was talking about.

Neu_maddox

First, thanks NismoPick, I thought the x100mmHg equaled up to 1 psi, similar to 1X100 RPM, like I said I'm new to turbos, least now I know. Second snwbrdphat I just said I was new to turbos, Anyway I have a bunch of other **** at work to deal with before I can work on my own car so I'll update yall later

snwbrderphat540

oh hey it wasn't a rip on you, just saying i am not the one looking at the print on your gauge so it wasn't a comment about the new to turbo's things. that's just physics at that point and reading skill :P lol.

Neu_maddox

Yeah I should have looked closer at the gauge itself, obviously the turbo is spooling just fine but it was slower with the cat in, now that it has a straight pipe feels way better, had to replace my water pump today so I'll be looking at it tomorrow, some of my weird problems are probably just corroded connections, I missed a couple the last time