Yeah, good point. Just doing a mind dump.
Once you think you've got it all figured out, these damn things will always challenge you with something new. Why do we do this, my mind screams....

You just got to look at the number of 'my car won't start' threads, or fuel pumps running all the time etc etc. It does your head in. The answers have all been found before, but getting to the actual answer for each situation is a mind number. This one should be simple - like you say - staring us in the face. But............
You know what - I figure these cars are the antidote to alzheimers and dementia.
Alan

Alan, Possibly Porsche can use that in a slogan? Purchase an old Porsche stay sharp purchase a Honda/Toyota and get dementia. So far my 1987 has been pretty well behaved, knock on wood. It does not get the track use your car gets. The first part I changed out was the wastegate valve, the original worked fine but just wanted something newer in there to be sure.

Mark, misery loves company! The car was purchased in 1979 then imported around 1984 or so. No bogging down/power loss or clouds of smoke. I can pick up some carb cleaner later today. The wastegate dump goes into the muffler so would be hard to get a paper towel in there.

908/930, you are correct... wastegate into the muffler. I'll confirm that the IC is both firmly seated and bolted down.


Alan, I'll check the wastegate and report back on whether it's holding pressure below .8.

The cam timing train of thought was coming from a video I watched from ************. In the video he drives a car that appears to accelerate fine but has no boost whatsoever. He finds that the cam is different from factory which shifts the powerband. He adjusts the timing to account for this and the boost comes back... thoughts? It's been a long long time but I seem to remember my dad saying something to the effect of "it's got a hot cam in it" but this would have been close to 40 years ago.

https://youtu.be/8k8vhQlMXTk

One further comment (yeah, right). The WG may hold pressure just fine, meaning the rubber diaphram is intact, but that doesn't mean the valve isn't perchance stuck open. I'm about out of ideas.

Yes, I think to check the wastegate valve properly for exhaust leak it will need to be removed, possibly can remove pipe leading to muffler and check for leak there.

A hot cam 40 years ago is likely a SC cam, with CIS it won't run well with a high lift cam, you said it idles well. The engine did run properly when the car was stored years ago?

Thats why I am asking him to see if it can hold pressure below 0.8 bar.
If it can, the WG is out of the equation and we look elsewhere.

As for the cam timing - yes it shifts the band - by maybe a couple of hundred rpm one way or other. But by the time you get to 4000 rpm you have to be in to max boost, whatever. Never heard of a cam, or timing that went beyond that. And you should be making 'some' boost 500 rpm below that point, at worst. There is a limit to what sort of 'hot' cam the CIS cars can run. I am a fair way up that curve and still hitting max boost around 3500 - depending which turbo I am running (3LDZ/7006).
My take would be there is something wrong in the plumbing department.
I take it your power brakes are working OK? They work off the hose on the recirc valve housing.
Alan

LOL. There is a high correlation there. Lots of people with Toyotas/hondas do have dementia. Closed case.
Alan

He shouldn't have to remove the WG to test it - in the manner I suggested. Basically a bench test, in situ. Put in 6-8 psi on the gauge and see if air is pouring out - if it is dumping in the exhaust then it should be coming out the tail pipe. Either a very faint hiss from bleed, or it is all coming out the tail pipe.
Agree with the cam comments.
Alan

I'm thinking that if the wastegate actuator holds .8 bar does not indicate the exhaust valve on the wastegate will be sealed, if the valve is bent it could still be open. Pull the muffler off put a zork tube on will eliminate any back pressure from exhaust.


Just looked at your last post, popped up while I was writing, Yup, worth a try apply air and listen. EDIT, but that still wont tell you if the valve itself is leaking.

I’ll get to work on testing the Wastegate following Alan’s lead. Alternatively, I could find someone with a beach entry pool, put its butt in the water and look for bubbles!

Well, if the valve is stuck open, there won't be any air held - it will all be pouring out the exhaust.
Or am I getting myself muddled here?
Alan

Hmmm, the actuator is what applying air pressure to the line from the intercooler will test. But the valve that operates on the exhaust (hot side) is a different test.

You are correct - thinking on. The actuator part of the WG is a closed system. You will only detect leakage past the guide. It won't tell you if the valve is sealing. My mistake.
Dunno how hard it is to get to the valve with it feeding back to the muffler. Not seen that set up. But somehow you need to inspect the valve and seat. Yes, maybe you will need to pull the WG.
My mistake. Sorry,
Alan

Okay so I pulled the Wastegate after dialing my compressor way down to 10 psi. When I did this the first time around I was putting way too much pressure into the system, so much so that it didn’t matter there was a small tear in the diaphragm. When I put approx 10 psi through the control line simulating boost I could hear it coming from the exhaust pipe and there was no movement from the valve in the Wastegate. After pulling the Wastegate… (that was fun) got all but two nuts that I had to cut off with the Dremel. Will also need to source a threaded stud I had to cut off just to get the Wastegate out. The spring is pretty rusted there is a tear in the diaphragm though it still is very soft. The flange at the bottom of the Wastegate feels like it’s practically welded on to the cast body of the Wastegate so I can’t get the valve out. That’s going to takes some finessing with a torch to get it loose so I can get the valve out. So I think we may have found our smoking gun! I am a bit confused though. So given that the diaphragm has a tear in it the turbo isn’t able to overcome the spring pressure in the Wastegate leaving the valve closed. Wouldn’t I be seeing overboost because the Wastegate isn’t opening to vent the excess pressure? It seems you’d have to have a pretty big hole in the diaphragm to prevent any boost. My understanding is that when a Wastegate fails it fails in the closed position potentially causing catastrophic damage given that to fail open the valve would need to become so stuck that the spring pressure isn’t able to close it.

Wastegate Pictures
 

http://forums.pelicanparts.com/uploa...1743564655.jpg
http://forums.pelicanparts.com/uploa...1743564655.jpg
http://forums.pelicanparts.com/uploa...1743564655.jpg
http://forums.pelicanparts.com/uploa...1743564655.jpg
http://forums.pelicanparts.com/uploa...1743564655.jpg
http://forums.pelicanparts.com/uploa...1743564655.jpg

Good progress - that had to be fixed anyway - but likely you found the cause. Was about to post another plan.
If your WG is plumbed right, the top port should be venting to atmosphere. if so, that is where your boost is likely going. The diaphragm is probably stretching that hole open significantly under boost.
Those WG studs are regular metric type exhaust studs - easily sourced, but you will probably need some decent heat to free them from the body.
You can probably gently chisel that valve seat free. It should crack off without too much persuasion. A small cold chisel gently tapped into the edges all round should do it.
Good work.
Alan

If it is not too late, can you figure the orientation of the spring housing to the base? If so, mark two matching points. I have center popped the top and bottom bits (one of the bolt lugs). You will likely need a press to get the spring housing back in place. It is a PITA to get there then find the orientation is wrong for the base port.
Alan

Time for a TiAL f46 waste gate and a shorty dump pipe?
Sounds awesome when the wastegate opens!

You can then rebuild you stock one at your leisure if you want.

I was just about to post the need to dissemble your wastegate and check the diaphragm but you beat me to it. This was one of the first problems I faced when hunting a similar problem 10 years ago. I was shocked the diaphragm was 200+ back then but after checking with our host it is still priced about the same today. Be very careful on reassembly, I remember this job being somewhat of a pain.
Good luck!