2G 2g low power, and not much boost

[mavaveric]

I have a 97 talon that is really down on power.

It spools the turbo slowly up to probably 4 psi. I need advise as to what could be wrong. I checked the exhaust by disconnecting the downpipe and it ran the same. The intake appears to be clear and flowing, (though, the car does feel faster at 3/4 throttle than at full throttle). I checked for boost leaks, and I didn't find anything major. I regapped the plugs, which solved a separate issue with the car stuttering due to spark blowout. I checked the wastegate of the turbo, and it feels like its closing all the way, though i could not visually confirm this. The turbo itself seems to be in decent health. (No major shaft play or cracks.)

The car has 112,000 miles, so I'm sure the turbo is at the end of its life, if all else fails, I'll throw a big t28 in it and see what happens. I inspected the exhaust manifold for cracks, and it seems fine.
I'll be starting down the fuel route next week, starting with the fuel filter. After that, I'll probably put a gauge on the fuel line to take a look at the pressure.

If anyone has any clues as to what could be wrong with it, please do advise.
PS. The car is stock. Bone stock.

 

[SixBolt_16G]

I checked the exhaust by disconnecting the downpipe and it ran the same.

I inspected the exhaust manifold for cracks, and it seems fine.

Have you checked for leaks at the exhaust manifold gasket and the other end at the turbo manifold gasket? Could cause a lack of power since the exhaust gases meant to spool to turbo are escaping.

 

[mavaveric]

Have you checked for leaks at the exhaust manifold gasket and the other end at the turbo manifold gasket? Could cause a lack of power since the exhaust gases meant to spool to turbo are escaping.

I have not specifically checked, though i imagine a leak like that would sound like an exhaust leak.

 

[SixBolt_16G]

I have not specifically checked, though i imagine a leak like that would sound like an exhaust leak.

I havent noticed a change in my exhaust tone, at least not from the driver's seat... But both my gaskets are definitely leaking and I have similar power loss that you are describing. Especially when I come off the gas to slow down and have to get back on it... Long hesitation before it starts accelerating again..

Might not be your problem but worth checking out...

 

[dwb]

My first thought is a major boost leak. Did you check the function of the PCV valve when you did your BLT? How's your idle?
Second thought is an issue with the wastegate flapper or its seat. I've seen severe cracks around the wastegate on high mileage turbos.

 

[mavaveric]

My first thought is a major boost leak. Did you check the function of the PCV valve when you did your BLT? How's your idle?
Second thought is an issue with the wastegate flapper or its seat. I've seen severe cracks around the wastegate on high mileage turbos.

I tried operating the wastegage by hand, and it opened and closes aright. Its possible that its cracked inside such that the exhaust all bypasses the turbo, but im pretty sure none of it is escaping before the muffler

 

[dwb]

I tried operating the wastegage by hand, and it opened and closes aright. Its possible that its cracked inside such that the exhaust all bypasses the turbo, but im pretty sure none of it is escaping before the muffler

You will have to visually inspect it. So you need to at least separate the O2 housing from the turbo.

What was your method for boost leak testing and did you find any leaks?

 

[mavaveric]

You will have to visually inspect it. So you need to at least separate the O2 housing from the turbo.

What was your method for boost leak testing and did you find any leaks?

I made an adapter that pressurizes it just past the turbo. I gotta get a silicone coupling to include the turbo in the test.

 

[mavaveric]

My first thought is a major boost leak. Did you check the function of the PCV valve when you did your BLT? How's your idle?
Second thought is an issue with the wastegate flapper or its seat. I've seen severe cracks around the wastegate on high mileage turbos.

I did not check the PCV valve. Its just a check valve right?

 

[dwb]

I made an adapter that pressurizes it just past the turbo. I gotta get a silicone coupling to include the turbo in the test.

Good. Did it hold pressure at all?

I did not check the PCV valve. Its just a check valve right?

Exactly.

 

[mavaveric]

Good. Did it hold pressure at all?

Exactly.

I am currently retesting it through the turbo, and i noticed one of the injectors hisses slightly. Also, i took out the check valve, and i can blow through it both ways. It doesnt seem to seal perfectly, is this normal, or should it seal perfectly?

 

[chrysler kid]

Do you actually have a boost gauge besides the stock gauge, or are you just saying it feels like its not making any boost

My stock 96gst felt like it had no turbo until I got hard intercooler piping. The factory rubber piping hoses were so worn they would expand and take a lot of the punch out of the turbocharger spooling

 

[mavaveric]

Do you actually have a boost gauge besides the stock gauge, or are you just saying it feels like its not making any boost

My stock 96gst felt like it had no turbo until I got hard intercooler piping. The factory rubber piping hoses were so worn they would expand and take a lot of the punch out of the turbocharger spooling

I do not have an aftermarket boost gauge, but the car definitely isnt boosting as hard as it should. Its not just the spool time, but the maximum boost is nowhere near what a stock TSI should be. At max boost, the car is about on par with my NA solstice 2.4... the boost gauge is at 7/8 full. I went for a ride in my co-worker's stock GST, and that thing would blow the body panels off of my car. Ill be fixing the PCV valve leaking, the injector boost leaks, check fuel pressure, and install a wideband O2 sensor this week to try and narrow down the issue. I checked the shaft play on the turbo last night, and it has a bit of lateral play, but no in out play. It spins pretty easy too

PS. I ran the car with the PCV valve line plugged, and it was pretty much the same, so I dont think that was knocking too much boost

 

[mavaveric]

Do you actually have a boost gauge besides the stock gauge, or are you just saying it feels like its not making any boost

My stock 96gst felt like it had no turbo until I got hard intercooler piping. The factory rubber piping hoses were so worn they would expand and take a lot of the punch out of the turbocharger spooling

Since Im a cheap SOB, you figure i could wrap my IC piping in wire or something to keep it from expanding?

 

[chrysler kid]

Since Im a cheap SOB, you figure i could wrap my IC piping in wire or something to keep it from expanding?

Im not sure if that would make a difference or not

The stock blow off valves are also known to be very leaky. If your friend has a gst he may have an extra blow off valve to swap to see if yours is leaking out boost.

 

[mavaveric]

Im not sure if that would make a difference or not

The stock blow off valves are also known to be very leaky. If your friend has a gst he may have an extra blow off valve to swap to see if yours is leaking out boost.

How could i check to see if its my BOV leaking? Would it leak when i do a boost leak test, or would it only show up under normal operation. With the leak test, i can pressurize it to 15 psi or so before my air compressor runs out of volume cuft-min of output.

 

[dwb]

How could i check to see if its my BOV leaking? Would it leak when i do a boost leak test, or would it only show up under normal operation. With the leak test, i can pressurize it to 15 psi or so before my air compressor runs out of volume cuft-min of output.

The BOV would leak into the recirc hose during a BLT, if it's leaking. Take the recirc hose off, pressurize the intake, hold your palm over the outlet and see if it builds pressure.

What sort of air compressor are you using? Is it tankless? The intake should HOLD air, not just keep up with the output of the compressor. Furthermore, it helps a ton to have a quiet space to listen for big leaks. So either a tank or long hose to locate the compressor away from your work space (a long enough hose can also act as a tank).

 

[mavaveric]

The BOV would leak into the recirc hose during a BLT, if it's leaking. Take the recirc hose off, pressurize the intake, hold your palm over the outlet and see if it builds pressure.

What sort of air compressor are you using? Is it tankless? The intake should HOLD air, not just keep up with the output of the compressor. Furthermore, it helps a ton to have a quiet space to listen for big leaks. So either a tank or long hose to locate the compressor away from your work space (a long enough hose can also act as a tank).

I have a big tanked compressor. Its just limited by how much air can pass through the Schrader valve at 150 psi.
Maybe my only issue is the BOV is leaking.
I noticed i can blow throught the PCV valve from the intake side into the valve cover and out the other vent, but someone said thats normal. To me, it seems like that would cause a pretty substantial boost leak.
How should the PCV valve normally operate?
and how should the BOV normally operate? Is there a spring setpoint at 14.5 psi or whatever where it will start to release the pressure no matter what?

 

[dwb]

I have a big tanked compressor. Its just limited by how much air can pass through the Schrader valve at 150 psi.
Maybe my only issue is the BOV is leaking.
I noticed i can blow throught the PCV valve from the intake side into the valve cover and out the other vent, but someone said thats normal. To me, it seems like that would cause a pretty substantial boost leak.
How should the PCV valve normally operate?
and how should the BOV normally operate? Is there a spring setpoint at 14.5 psi or whatever where it will start to release the pressure no matter what?

Be careful using unregulated air source. I usually set my compressor regulator to 5-10 PSI higher than what my target boost level is. I also use a quick connect adapter on my boost leak tester rather than a schrader valve, so I can keep constant pressure as I look/listen for leaks. Schrader valve should still work, but might make it hard to find major leaks.

PCV should allow air to pass from the crankcase into the intake manifold, but not the other way. If you can blow from the nipple (intake) side of the PCV, then you need a new PCV valve or maybe just de-grease the inside of yours. You should also hear a check ball floating around if you shake it.

There is a point where the BOV will leak at a certain boost level. I have no idea what pressure, and I understand the 2g BOV won't hold as much as the 1g. 1g can also be crushed to provide stronger spring tension/more boost but requires an adapter to work on a stock 2g UICP. A properly working BOV takes a boost source from the intake manifold, and if that is lower pressure than the UICP (i.e. throttle plate closed while boosting), it opens the valve to release excess pressure back to pre-turbo/post-MAF.

 

[mavaveric]

Be careful using unregulated air source. I usually set my compressor regulator to 5-10 PSI higher than what my target boost level is. I also use a quick connect adapter on my boost leak tester rather than a schrader valve, so I can keep constant pressure as I look/listen for leaks. Schrader valve should still work, but might make it hard to find major leaks.

PCV should allow air to pass from the crankcase into the intake manifold, but not the other way. If you can blow from the nipple (intake) side of the PCV, then you need a new PCV valve or maybe just de-grease the inside of yours. You should also hear a check ball floating around if you shake it.

There is a point where the BOV will leak at a certain boost level. I have no idea what pressure, and I understand the 2g BOV won't hold as much as the 1g. 1g can also be crushed to provide stronger spring tension/more boost but requires an adapter to work on a stock 2g UICP. A properly working BOV takes a boost source from the intake manifold, and if that is lower pressure than the UICP (i.e. throttle plate closed while boosting), it opens the valve to release excess pressure back to pre-turbo/post-MAF.

Im starting to think it might be the BOV leaking. Ill give it a test tomorrow and see for sure, but that would make sense. Iv heard that cars will fuel cut if they have too much boost leaking out of the system, but in my case, it might not be leaking out, just back into the intake again.

 

[mavaveric]

Well

Im starting to think it might be the BOV leaking. Ill give it a test tomorrow and see for sure, but that would make sense. Iv heard that cars will fuel cut if they have too much boost leaking out of the system, but in my case, it might not be leaking out, just back into the intake again.

Well, it doesnt seem to be the BOV. I took it out and inspected it, and it seems qlright. I can fill the pressurized side with water, and not one drop leaks through. The spring tension seems alright, probably around 15 to 20 lbs. I dont know what else it could be at this point. I know the car is desperate for new plugs/wires cuz it started pulsing and surging until i cleaned and regapped them. Though, i cant imagine any issues with the spark would cause it to have boost issues

 

[dwb]

Well

Well, it doesnt seem to be the BOV. I took it out and inspected it, and it seems qlright. I can fill the pressurized side with water, and not one drop leaks through. The spring tension seems alright, probably around 15 to 20 lbs. I dont know what else it could be at this point. I know the car is desperate for new plugs/wires cuz it started pulsing and surging until i cleaned and regapped them. Though, i cant imagine any issues with the spark would cause it to have boost issues

Yes, new plugs and wires would probably do wonders.
Get your PCV valve in order and try another BLT.

 

[mavaveric]

Alright, im back from my DSM sabbatical. i ran another BLT, and it seems like my BOV starts to just leak back into the intake at about 8 PSI or so. When I plugged the BOV recirc line, it pressurized up alright. ill get a new BOV and give it another go sometime in the next week or two.

Edit: The way I tested the BOV was wrong. The test revealed nothing.

 

[mavaveric]

I ran the car with a boost gauge and a plugged PCV valve. (only the one from the manifold, the other one is still opened.) The car rode right around 8 PSI and occasionally spiked to 10. If anyone has any advise as to why the turbo takes to long to spool, and why its a little low on boost, I'm opened to suggestions. Ill keep chuggin away at it, but I'm just about out of ideas, and Iv just about had it with this car.

 

[chrysler kid]

Is the boost solenoid hooked up too the waste gate.

The vacuum line from the turbo should to to the frame rail, to the boost solenoid with a T in it to go to the wastegatr