So I picked up an 87 rx its sweet! Other than this problem I am having diagnosing boost issues. car runs fine, but when I get in to boost it won't go past 4-5k rpm. Boost gauge only reads 1-2lb. Owner said he replaced the headers and I don't see any cracks in the header. Someone said the wastegate might be stuck open? I think it's a vf7 turbo. How can I check that without removing the turbo itself? Any help appreciated. Thanks

Oh also after I hold it at 4-5k rpm for a couple seconds it dies when I pop out in neutral if that helps anything.

I think this will work. Pull the vacuum line at the wastegate controller. This should cause the turbo to produce maximum boost, something like 20lbs. If no change at the gauge then I think the problem is either the controller or the turbo. 

The vacuum line from the turbo? I don't have any experience with turbo cars so I don't really know where the turbo specific stuff is located

my vf7 had similar issues and when I pulled it out I didn't see anything wrong but then I found a crack between the up-pipe and waste gate and figured that was the problem

So this little arm I assume is the wastegate control? the silver piece on the side of the turbo, connected to the actuator that has 2 vacuum lines on it. should I be able to move this back and forth when the car is off? What line would i want to pull at the controller? 

Update. The waste gate arm moves back and forth. Car still won't go past 4k

Maybe the problem is a clogged exhaust. I would think even if the turbo was not working, the engine should still be able to rev past 4K. 

I think this will work. Pull the vacuum line at the wastegate controller. This should cause the turbo to produce maximum boost, something like 20lbs. If no change at the gauge then I think the problem is either the controller or the turbo. 

I pulled the line on the back of the controller, and Tried revving it up in neutral and the car still wouldn't go past 4k or make any boost. 

With the black test wire connected and green disconnected the ECU flashes for 11, 22, and 23

How much does the wastegate arm move? You shouldn't be able to move that by hand at all.

How much does the wastegate arm move? You shouldn't be able to move that by hand at all.

I just have to pull really really hard on it and I can move it in and out no more than an inch. All the vacuum lines to the wastegate arm actuator seem fine. What is the black cylinder that the vacuum line from the actuator goes to? 

With the black tester connected and green disconnected. ECU gives these 3 codes.
11 crank angle sensor 
22 Knock sensor
23 air flow meter

could any of these be the source of my problem? Never even heard of any of these parts. 

I have the same problem as you in my 87 RX. My turbo has the Oil and water lines disconnected (I received the car like that) 

Now I want to put all the line were they goes.

My car don't pass 4k-5k rpm.

 

(English is not my natal lenguage)

Put a new (newer) turbo on today and no fix no vacuum leaks from soaking the engine in brake clean either. Same issue any ideas?

Put some Cat cleaner in the car today and it feels like it has a little more power now....still not enough. I have another downpipe but the problem is the exhaust is 1 piece from the turbo back with 1 cat. So I can't eliminate it

Could air flow sensor or knock sensor throw it into limp mode? When i rev it in neutral you can hear the turbo spooling

FINALLY making full boost! 7 lbs all the way to redline! idles nicer. Even sounds better than the single cat full turboback 2 3/4 exhaust that it had before with just an open downpipe now. The Cat was the problem, I suspect it was clogged. 

So you're running a catless downpipe now ?

Its the stock downpipe with the stock cat. just only the stock downpipe. So no exhaust from the first hangar back