Wastegate disconnected, fuel cut

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R

RHD Toyota's

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I disconnected the wastegate on 2L-TE equipped 91 Prado, now when I go up long hills under full load and get the red light overboost, it seems that it surges if I keep the throttle at the same position.

Any thoughts on whats going on, do you think this would be harmful?
 
Are you for real?
 
I say we start making bets on what happens first
A: The CT-20 turbo wheels disintegrate and get fed through the intake
B: The headgasket blows/head cracks/warps

My money is on the scenario A
 
Seriously though, this is probably what is happening: your ECU reads overboost conditions from the turbo, and cuts fuel to the IP in order to save your engine from the scenarios Sheldon describes above. On the 2L-TE, anything over 12 psi is overboost.

Are you running a boost gauge?
 
RHD Toyota's said:
I disconnected the wastegate on 2L-TE equipped 91 Prado, now when I go up long hills under full load and get the red light overboost, it seems that it surges if I keep the throttle at the same position.

Any thoughts on whats going on, do you think this would be harmful?
Click to expand...

The scientific answer: your turbine revs up past its safe maximum, building pressure up even more therefore your fuel pump reacts accordingly and power output increases. Since it is not throttled anymore, you feel the surge.

But be very careful, keep that up and your engine will literally blow its head off. I sure hope you have a boost guage and pyro installed. Especially considering you're doing this to the lightheaded 2 engine!!!

In other words... are you for real? ;)
 
these engines create a total of 14 lbs boost with the waste gate disconnected. the turbo is not spinning out of control.
the impeller fins are not going to let go.
the red light is over boost, the same setting for all Land Cruiser turbo equiped units.
i have experienced no surging on my own 2 LJ78s that have this mod done.
the one has been like this for about year and a half with over boost coming on frequently. make sure the line to the boost activator has not come undone below the intake plenum. that can happen.
you will not blow the head off the block (have you guys even seen one of these turbos?? they are tiny)

cheers
 
crushers said:
the red light is over boost, the same setting for all Land Cruiser turbo equiped units.
Click to expand...

Wayne, what pressure is it set at?

crushers said:
i have experienced no surging on my own 2 LJ78s that have this mod done.
Click to expand...

Maybe we need a definition for 'surge'. I definitely feel a power surge when the turbo really kicks in at around 1800RPM, for example switching from third gear to overdrive, it suddenly accelerates. My understanding is that at that RPM the turbo is the least throttled. But maybe I'm just experiencing great torque. It's just that it feels more powerful to me at that RPM.

crushers said:
you will not blow the head off the block (have you guys even seen one of these turbos?? they are tiny)

cheers
Click to expand...

Well that is reassuring :)... Just the head gasket, then? Or is the head issue with this engine strictly exhaust heat related?

Chris
 
crushers said:
these engines create a total of 14 lbs boost with the waste gate disconnected. the turbo is not spinning out of control.
the impeller fins are not going to let go.
the red light is over boost, the same setting for all Land Cruiser turbo equiped units.
i have experienced no surging on my own 2 LJ78s that have this mod done.
the one has been like this for about year and a half with over boost coming on frequently. make sure the line to the boost activator has not come undone below the intake plenum. that can happen.
you will not blow the head off the block (have you guys even seen one of these turbos?? they are tiny)

cheers
Click to expand...

I am not in the least bit suprised that YOU are doing this mod Wayne. I guess the difference is that you actually understand what you are disconecting and also are aware of the implications of the mods and potential risks. You are also probably running Boost and EGT gauges so you can actually tell what is going on in the engine.
I was not implying that the CT-20 was going to blow the head of the block. The crappy head design and less than adequate cooling system in the LJ78 should take care of the head without help from the turbo especially with this disco'd wastegate mod with no gauges.

RHD Toyota's, while you are disconecting stuff in pursuit of performance or whatever, why don't you pull that big black hose off that big round black container with all that restrictive folded up paper in it? Get back to us with the results :cool:
 
wow, so you think I'm a bit of an idiot allright, I guess my post sort of implies that, yes I have a boost gauge, no I still haven't installed a pyro, no this isn't my first turbo vehicle.

I've had several, 1 ton Powerstroke, FD3S Rx-7, Skyline GTR, Soarer TT, in my post I was saying surge to find out if any one else had felt that, and by surge I mean the very slightest, if you don't have a finely tuned ear you wouldn't notice it, because that is all it was. I'd say its more like in a fuel injected gas vehicle where the injection fuel mapping is changing over from a fuel economy setting to a more power setting, just when its on the threshold of change and then going back, trying to figure out the optimal setting. I guess I answered my own question by harmful, no, its just trying to figure out what to do with all that extra air by adjusting the fuel.

So in conclusion I was asking if anyone else has experienced this on their vehicle, sorry for sounding like an idiot.
 
70sguy said:
I am not in the least bit suprised that YOU are doing this mod Wayne.

why don't you pull that big black hose off that big round black container with all that restrictive folded up paper in it? Get back to us with the results :cool:
Click to expand...

Sheldon,
this made me laugh...thanks...
ROTFLMAO!!!!
 
RHD Toyota's said:
wow, so you think I'm a bit of an idiot allright, I guess my post sort of implies that, yes I have a boost gauge, no I still haven't installed a pyro, no this isn't my first turbo vehicle.

I've had several, 1 ton Powerstroke, FD3S Rx-7, Skyline GTR, Soarer TT, .
Click to expand...

Hey hey, just havin some fun. I didn't intend to be mean or anything. I appologize. You have now qualified yourself as a Diesel Cowboy like Wayne. Your first post did have me wondering. Instal that pyro and keep tuning.

You might be able to find some answers in the Electronic Wiring Diagram for that vehicle. If it is electronicaly controled there is a good chance there is some correlation between the overboost switch and the fuel volume control (unlike earlier TD cruisers) which may be causing your problem.

Sheldon
 
Just wondering .. when you ( Wayne ) are doing that ( 14 PSI ) you know that your head and gasket are pretty fine shape .. but if you don't know or not sure you are in risk .?
 
i have been running the wifes DD like this for at least a year, head shape unknown..
it is the heat that is the problem, not the boost. the extra boost actually drops the EGTs..
cheers
 
70sguy said:
Hey hey, just havin some fun. You have now qualified yourself as a Diesel Cowboy like Wayne.
Sheldon
Click to expand...

LOL!! <again>
Cowboy... can't remember the last time i was called that...
 
RHD Toyota's said:
I guess I answered my own question by harmful, no, its just trying to figure out what to do with all that extra air by adjusting the fuel.
Click to expand...

Keep in mind with a diesel that there is no stochiametric (sic?) ratio like a gasser, therefore no "extra" air relative to the fuel. Well, I guess it is "extra", but that's where you are getting your power!

My concern wouldn't be with overpressuring your head, but for overspeeding the turbine. They might be lightweight and small, but the centripital force is awesome on these units. Any cracking in the fins might cause it to destroy itself. Not to mention that the oil wedge it rides on is only good for a certain max rpm.

You could consider clipping the turbine or swapping out with a VTN. Now that would be cool...

Cheers,
Mike
 
lets see, turbine bushings only good for so much rpm...the shaft turns on a thin sheet of oil but only good for so many rpm....
i am going to disagree with this statement.

so many RPMs... interesting.

i guess i will have to call the turbo shop tomorrow and check out this statement...
just to sure you are stating these points as fact, correct?
 
crushers said:
i have been running the wifes DD like this for at least a year, head shape unknown..
it is the heat that is the problem, not the boost. the extra boost actually drops the EGTs..
cheers
Click to expand...

Yep... Give 'em more air! But I guess you have to make sure the engine won't over fuel either... have you had to reduce injection volume? What do the pyro numbers say after you simply remove this turbo mod? How does it behave on an 1HD-T? Ever tried?

As for blowing up: have you ever seen the head bolts pop due to excessive combustion pressure or does the gasket prevent that when breaking up? I'm asking because I've read somewhere in my years reading the List and forums there was an issue with head bolts breaking off due to excessive combustion pressure. I'm quite it was a Toyota issue, possibly in Oz, and that Toyota was selling upgraded bolts to remedy the problem. Not sure what engine had this problem, either.
 
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