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Discussion Starter · #1 ·
I have a second gen turbo mr2 1991 to be exact it suffers from overboosting issue on any gear I’ve replaced temp sensor, spark plugs wires distributor cap and rotor. Checked timing, replaced turbo, checked turbo vsv and actuator checked my hoses and the list goes on. I can’t seem to figure out what the overboosting issue might be. Also running super rich vehicle has hit fuel cut several times no mods or alterations done to the vehicle yet some advice would be appreciated thanks.
 

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Discussion Starter · #3 ·
I removed the clip that attaches the actuator to the shutter and was able to confirm the shutter moves freely. One thing I found tho is I did a smoke test and found the egr to be leaking coming from the manifold. I got a egr delete kit don’t know if that might help the situation
 

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Good to know wast gate moves freely. Can you hook up a bicycle pump to actuator port and check for movement? Only need about max 15psi.

Doubt if EGR leaking will be problem unless you are losing significant pressure from turbo compressor line. The turbo is a direct line to actuator so doubtful but worth fixing all the same.

Have you considered installing a MBC and eliminate TVS control?
 

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Discussion Starter · #5 ·
Good to know wast gate moves freely. Can you hook up a bicycle pump to actuator port and check for movement? Only need about max 15psi.

Doubt if EGR leaking will be problem unless you are losing significant pressure from turbo compressor line. The turbo is a direct line to actuator so doubtful but worth fixing all the same.

Have you considered installing a MBC and eliminate TVS control?
Well I have tested the tvs control (vsv) and it works as intended I can’t test the connection going to it due to being obd1 I can’t check if the ecu sending power to it (active test) But I guess that’s a possibility. Having a ecu issue I did check the wiring and it seems to be good.
 

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I don’t have a gauge hooked up no I been going by the stock gauge on the dash
Stock gauge on the dash tells you very little real world data. Ignore it completely. It just tells you that you might have boost, it's very slow and inaccurate. It also has no numbers on it so can't actually tell you if it's hitting the boost cut level.

You are best to check your actuator is working properly as a failed one or failing system will make it overboost. Having a guage just to test is good too. Even if you just borrow one.
 

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Discussion Starter · #11 ·
Stock gauge on the dash tells you very little real world data. Ignore it completely. It just tells you that you might have boost, it's very slow and inaccurate. It also has no numbers on it so can't actually tell you if it's hitting the boost cut level.

You are best to check your actuator is working properly as a failed one or failing system will make it overboost. Having a guage just to test is good too. Even if you just borrow one.
So I went ahead and used a vacuum gauge and applied pressure to the hose coming from tvs and plugged the one going to the turbo and got the actuator to move so that confirms the actuator is good. I did mention that it also runs super rich for no reason
 

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I know this is probably way too simplistic, but I don't understand how a vacuum leak can lead to running rich. If air is leaking past the AFM, wouldn't that mean that there is more air in the combustion chamber than what the ECU is expecting and therefore make it run lean?
 

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I know this is probably way too simplistic, but I don't understand how a vacuum leak can lead to running rich. If air is leaking past the AFM, wouldn't that mean that there is more air in the combustion chamber than what the ECU is expecting and therefore make it run lean?
Leak after metered air will cause it to go rich.

Mass air reads more air than actually makes it to the motor. ECU injects fuel for over metered air.... rich.

Same reason why a bov that isnt recirculated on a MAF car causes the engine to go rich.
 
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