Can low oil pressure cause low turbo boost? only boost 5lbs

[vangb2]

Recently I finish my 1jz swap but I have run into a few problems. Most problems that I ran into, I can usually find it in forums. But this problem that I have now is driving me nuts and I cannot find a solid answer in any forums.

I am having some troubles and problems with my set up. I went with single turbo (t88) and 55cc injectors. Everything runs fine but I cannot get my turbo to boost 5 lbs. It reaches 5lbs at 6500 rpm and then drops.

Test I have done:

One of the testing I did was remove the oil feed line to make sure there was oil pressure. The oil was squirting out while I had the motor running. I ran it for only 10 seconds and a good amount of oil came out. I do not have an oil pressure gauge so I do not know if the pressure is sufficient. I am using a -3an feed line.

I checked the return line to make sure that oil is flowing through the turbo. I removed the return line and also ran the engine at idle for about 10 seconds. The return of oil was slow but it may be because the return line is -10an and the feed line is -3an?

I have tested my pipes for leaks by using a tester I have made from materials at Menards. I have pressurized from the cold side pipe through intercooler to the intake manifold and it hold over 20 psi. I know that my piping system is not leaking. My manifold was also tested and it held over 20 psi.

I have hooked up my tester directly to the cold side turbo and it can still only produce 5lbs of pressure by the turbo. I have used an electronic boost gauge and a mechanical gauge and the boost is relatively close.

I've checked my wastegate and it’s not stuck open. I have pressurized the wastegate and it will open and close freely. I have try running the car with the wastegate not hooked up to see if boost will build up and I am still having the same issue.

I have checked my exhaust system to make sure it’s not clogged with anything. My exhaust will flow free.

I have spun the turbo fin slowly to see if there are any binding or free play, it seems to be fine.

Now, the question I have is; can low oil pressure cause low or no turbo boost? I have read some forums and it has mention that low pressure can cause low or no boost, I want to confirm this before I go through the amount of work required to replace an oil pump. Maybe a t88 is too big for 1jz? Can the turbo itself be bad with all good signs of it being ok?

Anyone has any suggestions that may help to solve this problem I am having? Are there any other test I can do that I did not cover in my test procedure? Anything will help.

Thanks

 

[di_rosa]

I have hooked up my tester directly to the cold side turbo and it can still only produce 5lbs of pressure. I have used an electronic boost gauge and a mechanical gauge and the boost is relatively close.

do you mean to say that when you hookup your pressure tester to the intake of the turbo, and cap it at the intercooler, it will only hold 5psi? if so, then obviously that's your probably, not your oil pressure. you said you pressure tested the intake side to 20psi fine, so i assume you mean the turbo side can't reach higher than 5psi, which is exactly what you're boosting, so you must have a leak somewhere on the turbo side.

 

[vangb2]

do you mean to say that when you hookup your pressure tester to the intake of the turbo, and cap it at the intercooler, it will only hold 5psi? if so, then obviously that's your probably, not your oil pressure. you said you pressure tested the intake side to 20psi fine, so i assume you mean the turbo side can't reach higher than 5psi, which is exactly what you're boosting, so you must have a leak somewhere on the turbo side.

I hooked the tester directly to the cold side of the turbine, only 5lb was produce by the turbine.

 

[jdub]

Oil pressure will not cause low boost...your problem is elsewhere.

Checked for boost leaks?

 

[vangb2]

Oil pressure will not cause low boost...your problem is elsewhere.

Checked for boost leaks?

Leak test was already done between turbo to intake manifold. All ok.

 

[di_rosa]

what is controlling your wastegate? boost controller? or is it hooked up directly to the intake manifold?

if it's a boost controller and you have a 10psi+ spring in your wastegate, try running it straight to the intake manifold

 

[vangb2]

what is controlling your wastegate? boost controller? or is it hooked up directly to the intake manifold?

if it's a boost controller and you have a 10psi+ spring in your wastegate, try running it straight to the intake manifold

At the moment I do not have anything controlling the wastegate. I have left the lines unplug so I can see how much boost it will make with the wastegate fully close. The wastegate has never opened with the exhaust pressure flowing against it. I should be able to produce infinant pressure until it explod with the wastegate closed, but its not producing any pressure.

thanks for your help again

 

[tissimo]

I hooked the tester directly to the cold side of the turbine, only 5lb was produce by the turbine.

If you pressurized the exhaust outlet (through the turbo to the exhaust manifold to the head) then your wastegate is opening/leaking.

 

[BOOSTEDSUPRA]

At the moment I do not have anything controlling the wastegate. I have left the lines unplug so I can see how much boost it will make with the wastegate fully close. The wastegate has never opened with the exhaust pressure flowing against it. I should be able to produce infinant pressure until it explod with the wastegate closed, but its not producing any pressure.

thanks for your help again

*bites fingernails*^^^ thats a scary thought! check your wastegate actuaters, arms, bushings, ect. possibly stuck open. im having same problem on my 7m, truboost not really producing what i think it should be at 90% duty cycle, aka full boost.

 

[Mastapip]

Maybe this is a stupid or too obvious suggestion but....

Have you pulled the turbo off the car since this problem started? Maybe there was some damage to the gasket between the exhaust mani and the hot side.

 

[vangb2]

Maybe this is a stupid or too obvious suggestion but....

Have you pulled the turbo off the car since this problem started? Maybe there was some damage to the gasket between the exhaust mani and the hot side.

I have not pull the turbo out because it is so damn hard to get the back bolt off. It will literally take like 2 hours to get the 2 bolt behind off. I guess taking the turbo off is not such a bad idea though. I will eventually have to take it off, maybe this weekend if I can find any other potential problems.

 

[wolf31685]

could be a exhaust manifold leak too i had that problem when i still had my stock 7m in my car but i was able to hear the leak double check all the gasketsfor the manifold turbo and wastegate

 

[tissimo]

I have not pull the turbo out because it is so damn hard to get the back bolt off. It will literally take like 2 hours to get the 2 bolt behind off. I guess taking the turbo off is not such a bad idea though. I will eventually have to take it off, maybe this weekend if I can find any other potential problems.

If you've pressurized the exhaust side then you would of found any leaks or did you not do this? If you didn't what did you mean by my previous posts quote?

 

[vangb2]

If you've pressurized the exhaust side then you would of found any leaks or did you not do this? If you didn't what did you mean by my previous posts quote?

I have not done the pressurize test on the exhaust side yet. I have pressurized only the cold side of turbo and it was holding a good amount of pressure. However, I will be taking off the turbo this weekend and do a complete check up on it off the car.

I will update with information after I take off the turbo so other people can use this help form in the future if needed.

 

[tissimo]

I have not done the pressurize test on the exhaust side yet. I have pressurized only the cold side of turbo and it was holding a good amount of pressure. However, I will be taking off the turbo this weekend and do a complete check up on it off the car.

I will update with information after I take off the turbo so other people can use this help form in the future if needed.

So you pressurized via the intake of the turbo and it only held 5psi? If so, you have a leak and need to locate it.

 

[vangb2]

So you pressurized via the intake of the turbo and it only held 5psi? If so, you have a leak and need to locate it.

Sorry for the confusion.

I pressurized the cold side and it held over 20 psi.

I use the engine exhaust gas to spin the turbo and rev it over 6500 rpm and it push out only 5 lbs.

 

[Dylan JZ]

its a t88 on a 1J, be happy you even saw 5psi :biglaugh:

 

[dslocal]

Ya it seems pretty simple to me, A t-88 is a huge turbo for a 2.5l engine, where the hell did you even get it and also do you have any specs on it?
I'm supprised no one thought of this before him^

 

[foreverpsycotic]

Try doing a 4th gear pull from 4k RPM to 7krpm. Log boost.

 

[tissimo]

T88 isn't that big. yea it wont hit till probably 5500 or so (unless its a GT47-88 then 6000-6500). I suspect a bad wastegate (do you hear it opening?) if not a bad turbo.