Waste Gate problems!!??

[calcifer]

Ok, I need a little help, please. I've done some basic troubleshooting on this and I don't know what to do next. I believe my wastegate isn't opening, because when I'm full throttle in 1st or 2nd, my fuel cuts at about 5000 rpms. I have tested my waste gate actuator by putting a pump on the end of one of the vaccum lines that goes to it and clamping off the other line (I think goes to the turbo inlet). The actuator arm moves fine when I pump it. Someone said if the actuator wasn't the problem, it would be the waste gate solenoid. Is this the valve on top of the stock air can? Is it the same as the bcs controller? Either way, I replaced that valve and I still have the problem. Is that the right thing to replace or do I need to replace something else? Any ideas would be greatly apprecciated, I'm tired of this problem. Thanks in advance. By the way, I have a '92 Plymouth Laser AWD Turbo.

 

[calcifer]

If nobody can help me trouble shoot can, anyone at least tell me where the waste gate solenoid is? I would really appreciate it. Thanks.

 

[steve]

The BSC could be called the wastegate solenoid by someone who doesn't know DSMs but I doubt thats your problem. If it was defective and open all the time it couldn't leak enough air to cause fuel cut. Even with the free BSC mod you only see a couple of psi increase over stock. If there was a problem in your wastegate system you would see it as abnormal boost readings. So, what boost do you see when this happens and what are you reading it with.

Are you sure your seeing fuel cut? It's extreme when it happens.

Have you pressure tested your intake system to make sure you don't have boost leaks.
Leaking pressure under boost will give you normal or low boost readings but high MAF readings that trigger fuel cut.

Steve

 

[calcifer]

Ok, I've been reading alot of previous threads (still not alot of help, but maybe something) about waste gate problems. If I get a MBC, does that completely bypass the stock bcs? Could this possibly solve my problems?

 

[calcifer]

Thanks for your reply Steve, I was posting just as you were. OK:

1)I don't have a real boost gauge, and I don't remember what the stock one showed before this started happening.
2)I THINK I'm hitting fuel cut, here's what happens: WOT in 1st at about 5k car lurches real hard, I shift 2nd WOT to 5k same thing.
3)I have not pressure tested for leaks yet, I just read the vfaq on how to make a pressure tester.
4)I also read something I think you posted in another thread:

If you replaced all the vaccum lines, I guess that means you also replaced the lines between the turbo outlet nipple/BSC/WGA.

There was a metal restrictor orifice in the original hose to slow how quickly the pressure source fills the hose and allow the BSC to bleed off some of the pressure in the line to the WGA and raise the boost pressure.

Without the restrictor the BCS can't vent enough air to drop the pressure in the line to the WGA.

Steve

from

http://www.dsmtuners.com/forums/showthread.php?t=81488&highlight=waste+gate

could something have happened to that restrictor? I haven't changed the hoses.

Thanks for your help!

 

[steve]

OK, you need a real boost gauge before you do much else to your car. Put it on the top of your list.

It does sound like fuel cut. Fuel cut is caused by the ECU seeing too much air going through the MAF compaired to what it expects. That might be because of a failing wastegate or it might be because of leaks in the intake system causing the turbo to work overtime to make the same intake boost pressure.

The stock system with a BSC is a bleeder style. The restrictor in the hose limits how fast the turbo can fill a pressure column made up by the hoses to the WGA and BCS. The BCS leaks off some of the pressure in that column reducing what the WGA sees, delaying when the WGA opens. If the restrictor is missing the BCS can't leak enough to lower the pressure and the WGA opens just like if it was connected directly to the turbo outlet nipple. If there was a leak in the hoses you could see the WGA not opening or opening at a much higher boost pressure than normal. So a missing restrictor causes lower boost not higher.
The service manual test for the WGA is to do what you did. Apply pressure to the WGA and measure the pressure when it begines to open. It should be around 7 to 10 psi.
If your WGA works you can test the BSC by applying pressure to it's nipple and making sure it holds pressure until 12v is applied to the terminals. If you do this by applying pressure to the hose attached to the turbo outlet you can see if the hoses leak too.

I think your problem is more likely in the intake than in the wastegate system unless you have a hole in the hoses.

Steve

 

[calcifer]

Steve thanks for all your help, I really appreciate it! The reason I haven't gotten a boost gauge is because the car is stock, but I will get one because I want to do some mods to it. If I follow the vfaq for the leak test, will that be testing all the intake hoses as well? Or do I need to check those some other way? Again, thanks for your help, this has been a problem for several months now, and this is the first GOOD help I've been able to get.

 

[steve]

If I follow the vfaq for the leak test, will that be testing all the intake hoses as well? Or do I need to check those some other way?

Pressure testing the intake by connecting a air source to the intake of the turbo will pressurize everything including the various vacuum lines and hoses. Finding the leaks can be difficult for the smaller ones. Using soapy water can help just like when your looking for leaks in tires, you watch for bubbles.

You do need a good gauge to know if the intake is holding pressure and to make sure you don't put too much pressure in. Don't use more than 15 psi to start with. The WGA diaphram can burst if you apply too much pressure to it.

Steve

 

[calcifer]

Ok, I'm going to try this when I get some time (maybe next weekend), and I'll post back my results. Hopefully I will find a leak and fix it. Thanks again for all your help, Steve.

 

[PSI_Tom]

I don't think anyone mentioned it could be an ignition issue.....

http://dsmtuners.com/forums/showthread.php?t=147637

Every time I've experienced "blow-out" it's been in first and second gear only, and above ~4500rpm. Based on your description, that's what it sounds like to me. Fuel cut will throw you into the steering wheel and choke you with the seat belt, "blow-out" will make the car lurch/sputter a bit.

 

[steve]

Tom,
I considered it and that's why I asked if he was sure it was fuel cut.

I've had ignition problems and the result is pretty soft, a loss in power and a change in the exhaust note but nothing I would call lurching. Since a stock car wouldn't normally hit fuel cut I suggested checking the intake. A stock car will hit fuel cut if there are large air leaks under boost. It would also run rich under boost and possibly lean under vacuum if the leak was big enough.

You have a good point and one that should be checked.
How old are the wires and plugs?
Are you using something other than NGK plugs and what's the gap?

Steve

 

[calcifer]

Ok, couple things:
No sputtering, just full power to nothing in split second.
Plugs and wires are brand new, straight from the Mitsu dealership. I did not check the gap. I think it does run rich, I think I can smell a little gas when I shut the car off. Going to build myself a leak tester and check the intake, as that sounds like what is happening. Thanks for all your help guys.