Top End Boost and WG Adjustment

[Speed_Dreamin']

Mods to my 87 GN:
9 in K&N
rebuilt TA49 (unconfirmed, just bought the car)
stretch intercooler
Dutweiller neck
RJC Power plate
3 in DP
Test Pipe
2.5 in cat back w/ turbo flows
Hotwired Walbro 340
Adj FPR
009 injectors
Hood Mount FP gauge
Scanmaster 2.0
Unknown chip
119K unrebuilt, otherwise stock engine

When I bought the car the Autometer boost gauge was reading 8 lbs max. Really had to get into it to see any boost, turbo would not spool, would not even spin the tires while attempting to brake torque. 3 turns on the waste gate rod, instant (comparitively) spool up to 10 lbs and the car smokes the tires with a brake torque. 3 more turns on the waste gate rod and the gauge still reads 10 lbs. Yes, I'm sure I was not just spinning the rod, but actually decreasing the length of the rod. The Y connector has the fork pointing towards the compressor housing. What are some things I could check?

Also, I noticed that there seems to be an actual mechanical stop internal to the turbine housing. If I swing the arm to the left stop and then back to the rightI can feel a stop, shake it around a bit and it will continue to move to the right and stops again - I cannot get it to move beyond this point. This 2nd stop happens to be right where my actuator rod is sitting right now, even if I wanted to further increase boost I'm not sure that I could. What's going on here?

 

[bison]

Un-bolt the downpipe from the exhaust housing on the turbo and verify that the swing valve assembly is free and not binding before it seals against the wastegate hole. Also check to see if the wastegate puck is sealing on the wastegate hole. If there is an exhaust leak there you will have lower boost levels and slow spoolup.

 

[Speed_Dreamin']

Checked this today. I think the 1st stop was the puck pivoting in it's arm and binding - the edge of the puck making contact with the housing surface and not puck surface to housing surface. The second stop is the puck making contact with the wastegate hole. It apears that it is sealing correctly. With the downpipe bolted up the swing arm is in about the 5 o'clock position with the puck fully seated against the wasegate hole, it will not advance ccw any further. In this position the gauge shows 10 lbs. I don't see how I could increase boost, this valve assembly seems to be maxed out.

I've tightened all band clamps, exhaust manifold does not appear to be cracked, what else can I look for? Why am I only seeing 10 psi? Can boost be limited electronically, through the ECM?

Also, what is the electrical connector on the pass. side valve cover? Taps from the wastegate actuator and compressor are fed to it, one port on this connector assembly was open so I capped it.

Thanks for your input.

 

[ES1]

1) I would run a vaccum pump to the boost gauge to make sure it is reading correctly.
2) On the passenger side VC, the part you are talking about is the boost solenoid.
1 port is un-capped the 2nd (does not matter which one) is for the boost line that goes to the turbo & wastegate.
Where the boost line splits there should be a Y connector.
Straight leg to turbo, split arm to the wasteagte.
3) Should be no bind in the puck.

 

[bison]

Do not cap the un-capped port on the solenoid. You will prevent the ecm from bleeding off pressure and increasing the boost.

 

[Speed_Dreamin']

If the puck is making contact and sealing against the wastegate hole, with no further room for advancement, shouldn't the turbo be making maximum boost - 25, 30 psi? If the gauge was bad and the plenum was seeing higher boost levels than indicated it seems that it should be so high that I would've done some serious damage running on 93 octane. Am I assuming incorrectly in the adjustment of the wategate? Are you supposed to force the swing arm assembly to the right after it has bottomed out? Seems like this would cause damage to the arm.

 

[ES1]

The wastegate is normally closed, held shut by a spring inside the actuator canister. When preset pressure limits are exceeded, the actuator progressively opens the wastegate, allowing exhaust flow to bypass the turbine, thus regulating manifold boost pressure.

I had a kink in my boost guage that did not show proper boost.
That's why I said to check it with a pressure device like a Mighty Vac.

 

[SHADOWII]

Are you ....

positive the puck is sealing against the seat? place a little bit of grease around the edge of the puck, and operate it to see if it leaves a complete print on the seat. Sometimes the hit a bit off center. Your assumptions sound correct. Have you tried to turn the turbine shaft by hand? Maybe the bearings are coked and the shaft is dragging in the bearings?

 

[scottyb]

Your first attempt to raise your boost was sucessful turn-for-turn. This leads me to believe that the WG and exhaust are OK. I bet your problem is with the solenoid/WG plumbing/Y connector in wrong and possibly in combination with a boost gauge that's off by a few lbs. Make sure the restriction in the Y is connected to the compressor.

The factory WG actuator is ~10 lbs, and only adjustable via the rod by about 4 or 5 lbs before it becomes unreliable. You're generally in the ballpark if you consider that the boost gauge may be off.

You MAY want to do this as a test after checking the Y, but do it GINGERLY: Discnnect the WG plumbing from the actuator, and take it for an easy spin don't WOT, just give it enough throttle to see if it exceeds the 10lb barrier you have now. Don't go over 14. If the boost does go up, then you know the exhaust/turbo/WG puck are not to blame - rule them out. If it does not change, then you have almost ruled out the solenoid/Y/actuator. Just be careful not to let the boost spike too high.

 

[Speed_Dreamin']

If the restrictor is not to the compressor and I switch it so that it is, could I then experience too high off boost for the current configuration to support (93 oct. and unknown chip). I'll take it easy just to be safe.

 

[scottyb]

If you find that the restrictor is wrong, then I suggest fixing that AND adjusting your WG arm back out. With the arm adjusted so that it takes a small tug to hook it (~1/8 inch), and all WG plumbing correct, you should get accurate chip control as designed. Watch the boost and the knock.

 

[Speed_Dreamin']

Well, the restrictor side of the Y is connected to the compressor. I removed the pressure ref. hose from the compressor and went for a careful drive. At 1/4 throttle the gauge rockets passed 10 psi, I immediatley let off, don't think the gauge went passed 15. I assume this means the WG actuator is bad, probably the diapghram is worn and allowing leakage? Or could the Y just be a generic Y vaccum fitting and not have a restrictor? Maybe I'll replace both to be safe. Any suggestions on a replacement/upgraded WG actuator?

 

[scottyb]

No the WG actuator most likely is not bad. It works off of pressure. If it's leaking, then you'd get overboost and/or erratic boost all the time. There's either a blockage in the WG plumbing or the solenoid is bad.

What I still don't get is that your baseline was 7 lbs. The stock actuator is 10 lbs. A non-functioninf solenoid in a stock setup would give you ~10 lbs of boost.

 

[unix_punk]

cap

clarify if you have taken off the cap you said you put on what I assume is the solenoid. if you cap the open end of the solenoid you will not be able to increase boost at all... one side of the solenoid needs to vent to atmosphere. if the solenoid is toast and stuck closed you would also have this problem whether it was capped or not.

 

[scottyb]

clarify if you have taken off the cap you said you put on what I assume is the solenoid. if you cap the open end of the solenoid you will not be able to increase boost at all... one side of the solenoid needs to vent to atmosphere. if the solenoid is toast and stuck closed you would also have this problem whether it was capped or not.

This guy is right. I hadn't noticed that part of your post. If you capped that 2nd port before all of this started, there's your problem.

 

[Speed_Dreamin']

1. After 1st purchasing the car gauge read ~7 lbs.
2. Turned actuator rod 3 turns gauge read 10 lbs.
3. Turned actuator 3 more times gauge still read 10 lbs.
4. Removed DP to ensure that the puck was making contact an sealing against the WG. It appears that it is. Tightened all band clamps and capped open port on solenoid. Gauge still read 10 lbs.
5. Verified restrictor in Y is to the compressor. Removed cap on solenoid. Removed boost ref. line from compressor. Gauge ramps up very fast, I let off the throttle at or before 15 lbs.

 

[scottyb]

1. After 1st purchasing the car gauge read ~7 lbs.
2. Turned actuator rod 3 turns gauge read 10 lbs.
3. Turned actuator 3 more times gauge still read 10 lbs.
4. Removed DP to ensure that the puck was making contact an sealing against the WG. It appears that it is. Tightened all band clamps and capped unopen port on solenoid. Gauge still read 10 lbs.
5. Verified restrictor in Y is to the compressor. Removed cap on solenoid. Removed boost ref. line from compressor. Gauge ramps up very fast, I let off the throttle at or before 15 lbs.

During step 4, you capped the open port on the solenoid? So the port was open in 1, 2, and 3?

 

[Speed_Dreamin']

During step 4, you capped the open port on the solenoid? So the port was open in 1, 2, and 3?

Correct. Port was open in steps 1, 2 and 3 as well as 5. Drivers side port if it makes a difference.

 

[scottyb]

Well, hook the line back up to the compressor. Then unhook the remaining line from the solenoid. Take an EASY spin again. If the boost jumps, then hook it back up (so all is hooked up normal). Take another spin. If boost goes back to 10 then you can be almost 100% certain it's the solenoid not working, or no electric signal to operate.

The car doesn't have an aftermarket electronic boost controller, does it?

 

[Speed_Dreamin']

No aftermarket boost controller. Do you happen to know what fuse the WG solenoid is on? There are no other electrical components that are inoperable that I am aware of, so I doubt it's a fuse. Do you happen to know which pin in the connector is power and gnd and what the voltage should be? Can I get a solenoid at any autoparts store or would it be a dealer item?

Thanks so much for your help so far. It's quite a tease knowing the car is not operating at its full potential (not as fast as the current hardware can support).