so how do i check for a bad turbo? I have no boost at all till i floor it and when i do that i get 2 lbs of boost but when i let off back to 3/4 throttle it goes to 0.
pull the inlet elbow and check for shaft play (side to side in and out) and contact with the housing.
Wait...are you trying to build boost while just sitting in the car and revving it? Or is this while you're actually driving it?
You only get boost under load...free-revving will not get you boost.
If this is what you're doing, no boost is normal.
If this is happening while driving, then...
You should be checking for boost leaks before you check for a "bad" turbo.
You should also check to see if the wastegate is working properly. The WG flapper could not be closing all the way.
Both of these could cause low boost situations. A "bad" turbo would let you know by blowing clouds of smoke, or making nasty noises. They're not complicated devices, and don't just go "bad" and stop making boost.
ok so it could be that the wastegate could just be stuck open. Where is the wastegate located?
Usually on the turbo...
First...Check EVERY hose and connector between the turbo and the throttle body.
Make sure there are no split connectors and they are all tight.
If this is good, then look into the wastegate.
The wastegate is located on the exhaust side of the turbo. On the IHI turbo it is part of the turbo itself, instead of the outlet elbow. There is a rod underneath the turbo that connects the wastegate actuator to the wastegate flapper. The wastegate actuator is the diaphram-looking thing mounted on the compressor-side (front) of the turbo.
cool thanks going to check it now.
ok i found that rod now is there any way to check to see if its working? and can you move it without the engine running? cuz if you can i couldn't get it to move at all.
you shouldnt be able to move it without a considerable amount of force. there for you know that your wastegate is closed ;)
so how can i tell if its good? since i tightened the couplers i got 4 lbs of boost when i floor it. And how can i tell if its bad?
have you checked all of your vacuum lines/ capped them off?
yeah but one is kinda odd. it runs from the turbo then hooks to a "t" then it runs into the other "t" on the firewall, then runs to the drives fender well then from there im not sure. and from the turbo to the "t" there are check valves so vaccume can only go one way. and the line runs to the compressor side of the turbo.
do you have a diagram on how the vac lines run to and from the turbo so i can check them and make sure there right?
got the diagram found my issue. Someone put the main vac line to the wastegate so it opens when vac is put to it so no boost. I will fix it in the am and report back.
you have to carfully use compressed air into the hose that runs to it... if you force it too much you will pop the diaphram
well i found out not only were the vac lines incorrect but the boost controller has a vac barb missing and the vac barb on the turbo is missing. So i bypassed the controller basically looping the vac side of the turbo to the waste gate. Now i get 5 lbs of boost. Its a temp fix till i can ether repair the boost controller or get a gills valve. I am leaning to getting the gills valve.
any of the cheapo MBC on ebay will work just fine....
I could be wrong here, but that would mean that the wastegate is effectively bypassed, therefore giving you unregulated boost. The wastegate operates under pressure and not vacuum, so your turbo will always have exhaust pressure hitting the turbine. 5 psi seems very low in this case.
With that said, you might have boost leak as another problem. I had boost leak on my '86 until I switched over to better couplers and t-bolt clamps.
so replace the 23 yr old couplers with what? and where can i get them from? and if i bypassed the bcs why would i only have 5 to 6 psi? I thought on what i read on nato was that the waste gate opens at 10psi and im not seeing anywhere near that amount. Also does the turbo run all the time or does it only spool up when you go over 2500 rpm?
Is the boost valve that you bought a cheep E bay one? the one I'm talking about is a two piece system you have a T with an arow on it one side to turbo one side to the WG and the other to the controller. Im my case I was having issues and finally took the T apart and found that the arrow sticker on the T was on backwards.
no i have no boost controller at all. Is there a way you could make your own boost controller?