under boosting?

[RM12577]

alright last week i decided i was sick of my car eating tires so i went out and got some tension rods on, while i was under the car i found a nice big boost leak, one of my circle clamps was barely still on the car just flopping around on one of my hoses, now after i fixed the boost leak my car boosts less. it only gets up to 4 psi now and it was boosting up to 8 before i fixed the leak. why would it loose boost pressure after i found a boost leak? is this normal or maybe my turbo is toast from having a big boost leak for a few months? i could crank the boost up a bit but im worried that my turbo might be going out.... if this is normal then i can crank it back up a bit but i wouldnt think that fixing a boost leak would lower my boost... any input would be good as to what might cause this....

[float_6969]

What turbo? Was the leak on the hotside, or the cold side.

[RM12577]

I have a stock t25 in it and it is on the hot side i believe if i remember rightim going to check it this weekend for boost leaks with my tester, just hope the turbo is alright maybe ill hafta check it as well while im at it.

[bias]

I bet if you throw in a boost controller and set it at 8psi the car will feel a lot stronger than it did before at 8psi. Leaks can cause all kinds of problems when trying to get the right boost reading.

[RM12577]

well i have an hks wastegate on it so i can change the boost without needing to put in a controller. the stock one was cranking like 12-14 psi before i swapped it over so im guessing that the leak was causing some kind of weird problem ill crank it back up and do some leak tests on it again

[dattodude]

yeah just adjust the wastegate preload. It's actually good that you can restrict boost to 4psi. You could wire in a solenoid and a switch to keep the boost low for when you girlfriend/wife/friends borrow the car.

Remember also that the CA18 ecu has a 'boost solenoid' for when you are running good fuel. It raises the boost by 2psi. But you need your knock sensor to be working for that to 'kick in'.

[busteds13]

Remember also that the CA18 ecu has a 'boost solenoid' for when you are running good fuel. It raises the boost by 2psi. But you need your knock sensor to be working for that to 'kick in'.

how would that work. i thought wastegate was run by vaccum, and none of that vaccm sustem conects to the ecu

[dattodude]

maybe not in the US version..

The JDM version has a vaccuum solenoid, and a whole second map in the ECU for just such a purpose. There is a t-piece in the wastegate actuator line on the T25 that connects to a hard vaccuum line that goes around the back of the head to the solenoid.

The online CA18det PDF Workshop Manual doesn't show it.

The output is pin 5 on the ECU which controls the boost solenoid valve.
Modified by dattodude at 4:17 AM 2/8/2008

[dlong319]

All the US swap guides tell us to can all those solenoids. They say not needed and useless, but Nissan placed them there for a purpose. I wish I would have not thrown all my solenoids away.



P.S. What tells the ECU to kick that solenoid on/off.

[RM12577]

well i adjusted it and got no response, still will not boost over about 5 psi, no leaks other than a really small one somewhere on my manifold, seems like a little hose that needs a better clamp, not enough to drop the boost that much, i can drop the boost to 0 but not bring it up past 5. anybody know if i can swap an sr turbo without having to change anything else as long as i dont crank the boost up? might be a turbo going out... o and the solenoid thing i d/ced but i still have it and might connect it back up later still have all the hoses for it and everything... and butterfly valves that i dont have connected... will try cranking it up more and see if it affects it

[RM12577]

Ok the car has made me a liar, i cranked the adjuster another 4 turns which used to be about 1psi per turn and now its back to about 6 or 7 ish. im gunna leave it like that for now, might connect the electronic solenoid still later though.

[dattodude]

All the US swap guides tell us to can all those solenoids. They say not needed and useless, but Nissan placed them there for a purpose. I wish I would have not thrown all my solenoids away.



P.S. What tells the ECU to kick that solenoid on/off.

The knock sensor as far as I know. I haven't found an english manual that explains it.. I just know why it's there, and how to wire it up.

[busteds13]

maybe not in the US version..

The JDM version has a vaccuum solenoid, and a whole second map in the ECU for just such a purpose. There is a t-piece in the wastegate actuator line on the T25 that connects to a hard vaccuum line that goes around the back of the head to the solenoid.

The online CA18det PDF Workshop Manual doesn't show it.

The output is pin 5 on the ECU which controls the boost solenoid valve.

Modified by dattodude at 4:17 AM 2/8/2008

ive got a jap engine, and i dont thimk mine came with the engine, would this be bad?

or if it did come with it mines not hopoked up.....

ad my turbo hits 5lbs and dont go higher or lower at WOT, which is cool( less chance for the ever dreaded KABOOM!!)