Low boost, weird wastegate issues… (1 Viewer)

[FJBen]

@Laughingjackal and @PabloCruise came over and we starting discussing cruisers and boost issues.

@Laughingjackal has an
FJ60 with a 4bd1t, Garrett gt2252, front mount intercooler.

He has to mash it to get 11psi max.

I looked under the hood and the wastegate vacuum line was gone and the actuator just had a plug on it. I told them to get a piece of vacuum hose and put it on there.

When they hooked it up, they only got 8psi. When they tried to unhook and move the wastegate actuator arm forward, it only hit 4psi and got hot egt. Moved backward had better psi but still less than with no hose hooked up.

Not making sense to me. This turbo should
Be able to boost much more than what it is.
Running the best boost with the actuator line missing is also strange. My next 2 thoughts are these but maybe I’m missing something.

1: bypass the front mount a2a intercooler. Possible blockage or huge pressure drop causing boost issues. Removing the intercooler from the equation helps Troubleshoot a little.

2. What would cause more boost with the wastegate actuator hose removed. Not blocked on the turbo side, just open. Could a blocked intercooler or collapsing hose cause this? Is it venting back through that open port on the turbo to allow more boost?


I’m a bit stumped at the moment but would love some help/ideas from the turbo guys. @Dougal @gerg

 

[veiloctane]

@Laughingjackal and @PabloCruise came over and we starting discussing cruisers and boost issues.

@Laughingjackal has an
FJ60 with a 4bd1t, Garrett gt2252, front mount intercooler.

He has to mash it to get 11psi max.

I looked under the hood and the wastegate vacuum line was gone and the actuator just had a plug on it. I told them to get a piece of vacuum hose and put it on there.

When they hooked it up, they only got 8psi. When they tried to unhook and move the wastegate actuator arm forward, it only hit 4psi and got hot egt. Moved backward had better psi but still less than with no hose hooked up.

Not making sense to me. This turbo should
Be able to boost much more than what it is.
Running the best boost with the actuator line missing is also strange. My next 2 thoughts are these but maybe I’m missing something.

1: bypass the front mount a2a intercooler. Possible blockage or huge pressure drop causing boost issues. Removing the intercooler from the equation helps Troubleshoot a little.

2. What would cause more boost with the wastegate actuator hose removed. Not blocked on the turbo side, just open. Could a blocked intercooler or collapsing hose cause this? Is it venting back through that open port on the turbo to allow more boost?


I’m a bit stumped at the moment but would love some help/ideas from the turbo guys. @Dougal @gerg

I recently found a crack in my turbo air outlet before the intercooler. something worth checking.

1hdt Kinugawa TD05-18G, can't reach 20psi

thanks for this info i guess i have to lean out the fuel or even tighten up spring tension on the boost compensator to aim for 18:1 Negative. Increase the fuel. 18 parts air : 1 part fuel A leaner mix of 22:1 is 22 parts air :1 part fuel

forum.ih8mud.com

 

[mudgudgeon]

The whole purpose of a waste gate is to limit boost.
With no boost line connected to the actuator, there's nothing to open the wastegate.
Boost pressure builds up in the actuator until there's enough pressure to compress a spring inside it. Then the arm will move.

If it's been left disconnected with an open port, it may be siezed up a bit.

 

[mudgudgeon]

You could use a bike tire pump to put pressure into the actuator and see how much pressure it takes to get it to open, and make sure it closes all the way again.

Also, a boost leak anywhere will reduce available boost.

Where is the boost gauge line attached?

I'd leave the intercooler alone, but test the whole intake for leaks

 

[FJBen]

Thanks @mudgudgeon was one of my first questions as well, Do you have a boost leak? I think he said he had one before and maybe I misunderstood if he still had one now or not.

The actuator does move free when it’s unhooked, so it’s not frozen up. That would make sense then it should be the same is crimping off the actuator hose, I just wasn’t sure with the port open on the turbo, if that caused any other issues. That kind of threw me for a loop.

It seems like he must have a big leak somewhere because that 4BD, with that turbo should easily be pushing a whole lot more boost, especially set up with no wastegate.

That was my thinking for bypassing the intercooler just to make the shortest path and see if that would resolve the boost issue

 

[FJBen]

You could use a bike tire pump to put pressure into the actuator and see how much pressure it takes to get it to open, and make sure it closes all the way again.

Also, a boost leak anywhere will reduce available boost.

Where is the boost gauge line attached?

I'd leave the intercooler alone, but test the whole intake for leaks

I’d have to look again at his truck to see where the boost gauge is attached. That was kind of my other question was is the boost gauge working correctly or something off on it.

 

[Dougal]

Sounds like at 11psi (really low for a 4BD1T) the exhaust pressure by itself is blowing the wastegate open. He will be able to increase boost to probably 15psi by shortening the wastegate arm (or shimming the bracket or whatever works). But beyond that will need a wastegate actuator with a stiffer spring.
As @mudgudgeon said you can use a bike pump and boost gauge to check the opening pressure. I've found I get about 2psi less in operation than a bench test with a bike-pump.

I run ~23psi on my 4BD1T with no intercooler. Technically I have a front-mount but it's still in the box and needs a lot of surgery to fit.

Once you have the turbo setup to run the right boost you will need the fuel pump to deliver enough fuel.
4BD1T has a fuel screw on the side of the governor, it also has a rack limiter under a cap on the front of the pump that will limit fuel at around the 120cc/1000 shots mark (stock is 70cc/1000 shots, max is 180cc/1000 shots).

 

[AirheadNut]

I just wasn’t sure with the port open on the turbo, if that caused any other issues.

If the port on the turbo was open to atmosphere that will cause a significant boost leak.

 

[FJBen]

Sounds like at 11psi (really low for a 4BD1T) the exhaust pressure by itself is blowing the wastegate open. He will be able to increase boost to probably 15psi by shortening the wastegate arm (or shimming the bracket or whatever works). But beyond that will need a wastegate actuator with a stiffer spring.
As @mudgudgeon said you can use a bike pump and boost gauge to check the opening pressure. I've found I get about 2psi less in operation than a bench test with a bike-pump.

I run ~23psi on my 4BD1T with no intercooler. Technically I have a front-mount but it's still in the box and needs a lot of surgery to fit.

Once you have the turbo setup to run the right boost you will need the fuel pump to deliver enough fuel.
4BD1T has a fuel screw on the side of the governor, it also has a rack limiter under a cap on the front of the pump that will limit fuel at around the 120cc/1000 shots mark (stock is 70cc/1000 shots, max is 180cc/1000 shots).

Probabaly best to buy an adjustable wastegate and then go from there. I think we might try testing and tying off the wastegate actuator and see if there are more leaks or something else going on.

If the port on the turbo was open to atmosphere that will cause a significant boost leak.

Yeah I figured it would be a problem.

Sounds like the wastegate is either shot or really low psi, so the work around was to just disconnect the hose and that worked the best. However the exhaust pressure must be overtaking the unhooked wastegate as @Dougal said.

Hope that solves it.

 

[FJBen]

Sounds like at 11psi (really low for a 4BD1T) the exhaust pressure by itself is blowing the wastegate open. He will be able to increase boost to probably 15psi by shortening the wastegate arm (or shimming the bracket or whatever works). But beyond that will need a wastegate actuator with a stiffer spring.
As @mudgudgeon said you can use a bike pump and boost gauge to check the opening pressure. I've found I get about 2psi less in operation than a bench test with a bike-pump.

I run ~23psi on my 4BD1T with no intercooler. Technically I have a front-mount but it's still in the box and needs a lot of surgery to fit.

Once you have the turbo setup to run the right boost you will need the fuel pump to deliver enough fuel.
4BD1T has a fuel screw on the side of the governor, it also has a rack limiter under a cap on the front of the pump that will limit fuel at around the 120cc/1000 shots mark (stock is 70cc/1000 shots, max is 180cc/1000 shots).

Probabaly best to buy an adjustable wastegate and then go from there. I think we might try testing and tying off the wastegate actuator and see if there are more leaks or something else going on.

If the port on the turbo was open to atmosphere that will cause a significant boost leak.

Yeah I figured it would be a problem.

Sounds like the wastegate is either shot or really low psi, so the work around was to just disconnect the hose and that worked the best. However the exhaust pressure must be overtaking the unhooked

 

[FJBen]

Sounds like at 11psi (really low for a 4BD1T) the exhaust pressure by itself is blowing the wastegate open. He will be able to increase boost to probably 15psi by shortening the wastegate arm (or shimming the bracket or whatever works). But beyond that will need a wastegate actuator with a stiffer spring.
As @mudgudgeon said you can use a bike pump and boost gauge to check the opening pressure. I've found I get about 2psi less in operation than a bench test with a bike-pump.

I run ~23psi on my 4BD1T with no intercooler. Technically I have a front-mount but it's still in the box and needs a lot of surgery to fit.

Once you have the turbo setup to run the right boost you will need the fuel pump to deliver enough fuel.
4BD1T has a fuel screw on the side of the governor, it also has a rack limiter under a cap on the front of the pump that will limit fuel at around the 120cc/1000 shots mark (stock is 70cc/1000 shots, max is 180cc/1000 shots).

He tightened up all if any boost leaks. The wastegate wired shut.

Boost was much quicker but still topped at 10. He said the pump was rebuilt when he put the new turbo on.

Sounds like fueling?

 

[mudgudgeon]

Or mismatched turbo?
Or bad turbo?

Check the basics too, such as fuel filter, air filter, fuel lines and pick up clear/ not blocked etc

 

[FJBen]

Or mismatched turbo?
Or bad turbo?

Check the basics too, such as fuel filter, air filter, fuel lines and pick up clear/ not blocked etc

By all accounts the turbo should be a pretty good match for the 4bd1t. I suppose it’s possible the turbo is bad, but it seems to respond well and respond if the wastegate opens too soon as well.

I thought for sure wiring the wastegate would show more boost but nope, quicker now and sits right at 10-11.

I suppose a quick turn up on fuel screw would help diagnose.

 

[Dougal]

He tightened up all if any boost leaks. The wastegate wired shut.

Boost was much quicker but still topped at 10. He said the pump was rebuilt when he put the new turbo on.

Sounds like fueling?

Has he increased fuelling? Stock boost for a US spec 4BD1T was ~11psi.

 

[FJBen]

Has he increased fuelling? Stock boost for a US spec 4BD1T was ~11psi.

Not yet, that is the next step.

I would assume that gt2252 should have plenty of boost on tap to get to 20psi especially with an intercooler.

 

[Dougal]

Not yet, that is the next step.

I would assume that gt2252 should have plenty of boost on tap to get to 20psi especially with an intercooler.

That makes sense that you won't get past ~11psi on stock fuelling with an intercooler. That turbo will have plenty of room to increase.

 

[FJBen]

That makes sense that you won't get past ~11psi on stock fuelling with an intercooler. That turbo will have plenty of room to increase.

Great, easy enough to turn it up a little and test. Thanks!

 

[FJBen]

That makes sense that you won't get past ~11psi on stock fuelling with an intercooler. That turbo will have plenty of room to increase.

Turned up fuel some. Wastegate wired shut, port plugged on turbo wastegate

She will get up to 11 psi quick now, says it feels snappier but still will only max out at 13ish in higher rpm in 4th or 5th gear.

 

[mudgudgeon]

Turned up fuel some. Wastegate wired shut, port plugged on turbo wastegate

She will get up to 11 psi quick now, says it feels snappier but still will only max out at 13ish in higher rpm in 4th or 5th gear.

Peak EGTs if you stomp it, and keep your boot into it?

need to check EGTs under load, WOT, from liw RPM through to near redline-ish ( or peak power RPM), so up a long consistent uphill grade. Towing a heavy load etc

 

[PabloCruise]

Peak EGTs if you stomp it, and keep your boot into it?

need to check EGTs under load, WOT, from liw RPM through to near redline-ish ( or peak power RPM), so up a long consistent uphill grade. Towing a heavy load etc

@Laughingjackal