Can anyone point me in the right direction on my boost?

[fienloco]

I have recently replaced a head gasket on my 87 7-MGTE. It was a JDM swap the place sold me the engine saying it only had 45 thousand on it. Engine, Tranny, ECU, Wiring Harness, complete 1950bucks with shipping. I put the engine and tranny in the car married and all. Had to convert the throttle body as mine is left hand. Changed the wiring harness to my original as half the wires were hacked to hell. Originally she was dumping water into the crankcase. HG!!!! For those who got back to me on my first thread on here. i.e. BustedKnuckles and one or two others. Thanx.

Anyhow had no com. between the engine and the computer I then realized other things had to be swapped as well. Oil Press sending unit, t-stat housing, knock sensors, etc.

Done all and complete. Got some killer power out of her finally. Cooling system has a couple of qwirks gettn em resolved but she runs and runs well.

My issue is all boost at this point. I have replaced vacuum lines in and out and top to bottom. Everything is tight with all new gaskets on the top end. Hours spent looking high and low and double checking every connection I have made every inch of my baby. Im good at that.


I have found when driving her around that I am not creating maximum boost for a stock CT26 saddly enough. I get on her she spools she creates a bit of boost, doesnt display on the gauge. Only-4 to 0 psi? Then a bit of blow off. I want to know what if not a loose connection where this issue could be? Getting her straight and running like she is supposed to be is more important than my job at this point. I have spent a grip of time and money on her and the body needs the love next but I gotta get the engine straight first. Any help would be greatly appreciated and I thank all of on here who have taken time to point me in all the different directions I have been pointed on making my Supra all she can be. I have had issue after issue thread after thread and all of you out there have been dead on with the tips you have givin me. THANX!!!

[Stupra]

Originally Posted by fienloco

I have recently replaced a head gasket on my 87 7-MGTE. It was a JDM swap the place sold me the engine saying it only had 45 thousand on it. Engine, Tranny, ECU, Wiring Harness, complete 1950bucks with shipping. I put the engine and tranny in the car married and all. Had to convert the throttle body as mine is left hand. Changed the wiring harness to my original as half the wires were hacked to hell. Originally she was dumping water into the crankcase. HG!!!! For those who got back to me on my first thread on here. i.e. BustedKnuckles and one or two others. Thanx.

Anyhow had no com. between the engine and the computer I then realized other things had to be swapped as well. Oil Press sending unit, t-stat housing, knock sensors, etc.

Done all and complete. Got some killer power out of her finally. Cooling system has a couple of qwirks gettn em resolved but she runs and runs well.

My issue is all boost at this point. I have replaced vacuum lines in and out and top to bottom. Everything is tight with all new gaskets on the top end. Hours spent looking high and low and double checking every connection I have made every inch of my baby. Im good at that.


I have found when driving her around that I am not creating maximum boost for a stock CT26 saddly enough. I get on her she spools she creates a bit of boost, doesnt display on the gauge. Only-4 to 0 psi? Then a bit of blow off. I want to know what if not a loose connection where this issue could be? Getting her straight and running like she is supposed to be is more important than my job at this point. I have spent a grip of time and money on her and the body needs the love next but I gotta get the engine straight first. Any help would be greatly appreciated and I thank all of on here who have taken time to point me in all the different directions I have been pointed on making my Supra all she can be. I have had issue after issue thread after thread and all of you out there have been dead on with the tips you have givin me. THANX!!!

I read your other thread. If the gauge is reading properly then there must be something you over looked. It should read -19 to -22 lbs. while idling. I'm sure you've checked but the most commonly missed vacuum is that to the power steering pump. It runs all the way from the front side of the intake manifold, across the front of the engine, into the pump, and out to the intake boot. Also, are you recirculating your BOV?

[fienloco]

That is helpful do. Do you by any chance have a bit more detail on the recirc to the BOV possible of any vacuum diagrams as well. I have looked high and low for the info and cannot seem to find it.

[Stupra]

the only real diagram I have is in my head lol. I could try to help you through pictures? The reason I asked about the BOV is beacause if it's a stock BOV and it's not recirculating back into the intake, you're basically causing yourself a large vacuum leak. I learned this the hard way.

[fienloco]

Ok. The BOV is stock. Now what your telling me if I am correct is the vacuum line that is on the stock turbo loops from the turbo to the actuator/BOV. Right? Then off the intake boot down to the power steering pump off there across the front of the engine up the intake side to the I forget what its called on the fuel rail so the whatchamajigger (pressure regulator?) then into the intake. Correct? Thats how mine is ran off the top of my head. When you recirculating to the intake. I guess I would need an example or explanation. Im not interpreting how to do that. If its not like that stock. Anyway. Appreciate the help hope to hear back on this one.

[Stupra]

Originally Posted by fienloco

Ok. The BOV is stock. Now what your telling me if I am correct is the vacuum line that is on the stock turbo loops from the turbo to the actuator/BOV. Right? Then off the intake boot down to the power steering pump off there across the front of the engine up the intake side to the I forget what its called on the fuel rail so the whatchamajigger (pressure regulator?) then into the intake. Correct? Thats how mine is ran off the top of my head. When you recirculating to the intake. I guess I would need an example or explanation. Im not interpreting how to do that. If its not like that stock. Anyway. Appreciate the help hope to hear back on this one.

There is a short vacuum line that loops from the turbo to the actuator NOT the bov. The bov should have it's own vacuum source that comes across the top of the engine from the intake manifold. Now the power steering one is completely different. It comes off the bottom of the accordian hose(intake boot) into the pump, across the front of the engine and so forth. Yeah if everything is stock then your bov should be in between your 3000 pipe and your accordian hose. If you have left this stock then you should be ok. A lot of guys leave the intake side of the bov open hoping the get a better swoosh but this will make your car run bad under vacuum(idle) and lets un-metered air through which is basically a giant vacuum leak. That's why I asked. Keep pluckin away man! And make sure your boost gauge has a reliable vacuum source too. Because that would suck if it was just reading wrong this whole time!

[fienloco]

Right on. It is what its supposed to be if Im putting the info to my brain correctly. Now that I believe it is the issue this whole time. Because she spools blows of the steam. You know what I mean. My ? on the the vacuum now is the Turbo Pressure Assy. on the driver side inner fender the vacuum line runs from there to the cruise control acuator along the firewall T's into the intake nipple across the firewall to the heater vacuum somn or other I have looked and looked and asked trying to find where or what I'm missing because I believe my problem lies amongst that road. ????

[mkiiisupra]

Cygnus X1 Home Page

Vaccum line diagram

[Stupra]

Originally Posted by fienloco

Right on. It is what its supposed to be if Im putting the info to my brain correctly. Now that I believe it is the issue this whole time. Because she spools blows of the steam. You know what I mean. My ? on the the vacuum now is the Turbo Pressure Assy. on the driver side inner fender the vacuum line runs from there to the cruise control acuator along the firewall T's into the intake nipple across the firewall to the heater vacuum somn or other I have looked and looked and asked trying to find where or what I'm missing because I believe my problem lies amongst that road. ????

Yeah read check that diagram posted above it's a good one and easy to understand. Make sure everything looks right. If your boost gauge is reading correctly then it's definitely a vacuum problem. Like I said you should have somewhere around 20 pounds of vacuum pressure at idle

[Bill UK]

This is the stock set up for the BOV, the bov valve fitted is a SAAB bov half the price and more reliable, fitting instructions and lots of info HERE Click on modifications (left side of page) and then scroll down to SAAB Blow of Valve.