So I'm new to supras picked up an 88 7mgte for 1500 thing was a wreck, I've done alot to it but I'm having problems previous owner had head gone through put a 3 layer steel gasket and arp bolts I added new manifold seals on intake side and new radiator. The exhaust manifold has 2 to 3 bolts stripped out and I will be putting inserts in Tuesday. But as is the boost gauge is reading vacuum of 20 psi and no boost when giving it gas so I took off the aftermarket bov and I don't feel hardley any air flowing thru the tube, the turbo has no shaft play at all but I can't tell if it's functioning properly, I don't know how honestly, it also has absolutely no power and over heats I made sure there are no air bubbles in system and it currently has no thermostat waterpump is flowing and fan works could leaking exhaust manifold on a turbo car cause both those or do i have two separate problems.. Help!
7mgte troubles
- Thread starter Aaronrbrts
- Start date
Well i can point out the easy stuff to start.
Is you boost gage hooked up properly?
All your vac lines hooked up and in the right spots?
Is there coolant leaking or boiling out of the reservoir?
Any color of smoke coming from the tail pipe?
Did the previous owner deck the block or mill the head? Not having done either with a metal head gasket is a fast track to BHG (over heating much?)
Yes having a leaky exhaust mani can cause all sorts of problems, and so can having the metal head gasket with no surfacing done. Check your oil for milkshake.
Is you boost gage hooked up properly?
All your vac lines hooked up and in the right spots?
Is there coolant leaking or boiling out of the reservoir?
Any color of smoke coming from the tail pipe?
Did the previous owner deck the block or mill the head? Not having done either with a metal head gasket is a fast track to BHG (over heating much?)
Yes having a leaky exhaust mani can cause all sorts of problems, and so can having the metal head gasket with no surfacing done. Check your oil for milkshake.
you say ur not getting boost when u give it gas...are u DRIVING or just sitting there revving it? u wont see a boost reading on ur gauge if ur just sitting there revving it
^^ what he said
Fix exhaust leak
Honestly before fixing exhaust leak or boost problem you need to make sure your overheating issue isn't a BHG
Perform cylinder leak down test and combustion gas test
Fix exhaust leak
Honestly before fixing exhaust leak or boost problem you need to make sure your overheating issue isn't a BHG
Perform cylinder leak down test and combustion gas test
I have the same Problem with Low Boost at full throttle on my Mark III. I just put a Rabid Chimp Upgrade Turbo thinking that it would solve my problem. Also installed a new OEM innercooler and hoses. Tested the system for leaks. NONE! Is there a check valve in the Throttle Body that could be falty? I've done all the tests that the book calls for and still no boost above 0 lb. Checked it with an external Boost Gage. Still 0 lb boost. At idle it reads 17 Vacuum at 5500 ft. no leaks in the exhaust. ??? Thanks in advance for the blog.
Pardon me.... I should have said that the boost guage reads 0 at 5,000 rmp under load in any gear. Just tryin to get some advice on a Jap Rig. I've had boosted rigs from Flathead Fords and small block Chevys.. to Cummins and Jimmies. Had centrifcal and roots blowers plus winded garetts. Never been stumped till now!! My question is this... Is there a check valve in the throttle body that could be falty thus allowing boost to escape into a pcv valve or into the crankcase by another means? Or any other Boost Escape Port that could be at falt? Is the Boost Pressure regulated by Manual or Electrical Means. Does an engine falt light reduce engine performance thus reducing available boost potential so far that 0 boost is all the engine will produce? I should have been more specific. I'm sure there are other avenues to explore but lets start with these and work from there. Thanks in advance for you expertice in this area. Ron
I've tried several. The last one is an external hand held unit from my tool box. I ran it through the hood into the cab to double check the stock and aftermarket units. The best boost I get is 0 lb at 5,000 rmp under load at 5,000 feet above mean sea level. Prescott AZ area. I'm stumped. Like your car by the way!
Ok. I have had no time till now to anything my wife bought me a puppy for Christmas lol but I finally got back to it I tapped the exhaust bolts and gave it a new gasket and sealed it up I'm waiting to get taggs on it to really test it but down the road and back I've seen I think a high of 4 psi so I've bought the stuff for a leak tester I understand I want to block off the 3000 pipe before the tb 3 questions.. The car has no exhaust but a downpour off the turbo is this robbing power? 2: how much psi should a healthy stock ct26 push with no boost controller, and is a compression test the same as a leakdown test? 3 it has no tps I bought 1 online and I think it is for a different Toyota like maybe a 1jz 2 jz of a non turbo moddel, appears to be the same wiring and by rotateing the mettal piece on the end of the throttle plate shaft 180 degrees I can make it work are these sensors electronically interchangeable??
Also is there any way to test your intake manifold and engine vacume lines for a leak or boost leak after the tb ?? An easy way wo a fogger like a pressure test?
Holy crap.
You have no TPS on the engine?
Ok. We have to all be on the same page here, with regards to how your engine is set up.
You can't tell us" I'm wondering if I have a boost leak- i checked all the lines. Oh- And I'm about to install the 6th piston, would that affect it?"
I'm joking, but you get the point. Hopefully, one of the electrical gods on this forum will chime in as to the interchangeability of the TPS units. But you need that in there, period. Do you have a check engine light on? I assume you do.
1. Install a tps
2. Check the diagnostic codes that are being reported, and post them here.
3. Install a thermostat! Every time an idiot(not you, the previous owner) gets an overheating issue, they pull the thermostat. You can almost as easily overheat without any thermostat, as you can with a faulty thermostat. Don't think of a Tstat as something that blocks the flow of coolant; Rather, it's something that holds coolant in the radiator for the necessary amount of time to let the flow of air remove the heat from that coolant, before letting it go back into the block to grab more heat.
You have no TPS on the engine?
Ok. We have to all be on the same page here, with regards to how your engine is set up.
You can't tell us" I'm wondering if I have a boost leak- i checked all the lines. Oh- And I'm about to install the 6th piston, would that affect it?"
I'm joking, but you get the point. Hopefully, one of the electrical gods on this forum will chime in as to the interchangeability of the TPS units. But you need that in there, period. Do you have a check engine light on? I assume you do.
1. Install a tps
2. Check the diagnostic codes that are being reported, and post them here.
3. Install a thermostat! Every time an idiot(not you, the previous owner) gets an overheating issue, they pull the thermostat. You can almost as easily overheat without any thermostat, as you can with a faulty thermostat. Don't think of a Tstat as something that blocks the flow of coolant; Rather, it's something that holds coolant in the radiator for the necessary amount of time to let the flow of air remove the heat from that coolant, before letting it go back into the block to grab more heat.
Okay diagnostic codes are 22 24 51 52 I believe I have fixed 22 though the ect code.. The sensor came loose as it is all busted from age and being messed with. So I got tags and have been driving it a little today it doesn't really boost at all through first or second but under load in 3rd it hits ab 5 or 6 on the gauge. But when it gets to ab 3500 or 4000 it seems to just fall on it's face and boost goes back down below zero also have not put the tps on yet i tried but the harness is different mechanically it would have worked though lol. So I will be getting a new one soon
Also this is a total idiot question but I haven't installed a thermostat in a longgggg time they seldom go bad anymore it seems but which way is it installed spring toward block or toward the radiator in the 7mgte motor
Install spring towards block and there should be a little hole on the wide flat part of the thermostat and that hole ALWAYS faces upward 
to allow the air bubbles to be bleed out. Did you check your timing, cams and crank at tdc ( top dead center) make sure that they are aligning correctly.
to allow the air bubbles to be bleed out. Did you check your timing, cams and crank at tdc ( top dead center) make sure that they are aligning correctly.
Ron Crites;1794739 said:
The stock recirculater valve (or what most ppl call stock bov) could be stuck open and shooting your boost right back into your inlet tube. Take it off and and put a flash light to one end there should be no light coming threw or put your mouth to one end make sure there no air and push it with your finger it's spring loaded and should not move easily. Now check your waste gate on your turbo make sure the vacuum line is hooked up and move the little rod with your hand if it moves way too easy then your spring could be bad or broken if you have time take your turbo elbow off and check for cracks around the waste gate flange those cracks will leak exhaust bypassing your turbine wheel. Finally get a spray bottle and fill it with water make sure it's in mist. Now idle your engine spraying you mist around on your vacuum lines lightly not letting it build up and if you hit a leak you engine idle speed will drop almost to the point of dying and there will be your leak. Pm me or start a new thread if you need more help.
Also, there is a check valve right where your break booster is you can check that. You have too little pcv hoses right behind your 3000 cross over pipe And there are under a metal tube. There is also a really big pcv hose that runs behind your alternator going from your block to your driver side valve cover. I really doubt it's gonna be any of your pcv hoses.
And my last thing sorry lol. You should have a stock boost pressure sensor that tells your engine what boost you're at or vacuum check you voltage and ohm's
Code 52 is your knock sensor code.
I'm pretty sure you'll lose alot of power if you have that.
Check both knock sensor plugs on the drivers side of the block, under the intake.
One is on the side of cylinder #2, and the other is closer to the #6 cylinder, next to the starter.
I'm pretty sure you'll lose alot of power if you have that.
Check both knock sensor plugs on the drivers side of the block, under the intake.
One is on the side of cylinder #2, and the other is closer to the #6 cylinder, next to the starter.
Aaronrbrts;1798683 said:
22= coolant temp sensor, 24= intake air temp sensor, 51= air conditioner switch or neutral start switch signal, and yes 52= is your knock sensor. Got these form my tsrm.
