Boost creep/ cut out

[Nalleywhacker]

i just bought a 1jz supra the other day and its been boosting to 12psi and holding just fine, and tonight its been creeping to 15psi and cutting out, iam assuming its cutting out cause its going lean, but why is it all of sudden not holding at 12psi? could it be a bov problem or maybe something with the wastegates?

 

[suprahero]

If it's spiking then it's probably a restriction somewhere. Your wastegate may not be opening properly or maybe a cat crawled into your exhaust and died.............that's what Buckshot told me was wrong with my car so I thought I'd pass it on.

Definately check the wastegate. Do you have a boost controller on it?

 

[Nalleywhacker]

No, no boost controller so iguess another question is 12psi the stock boost for a 1j?

 

[Nalleywhacker]

another thing is it just started this since it got colder, could the cold have something to do with it? another thing i prob should have mentioned, the car is bone stock except for 3in dp and blitz exhaust (no silencer) if i put the silencer on would it solve it?

 

[suprahero]

no, you need more flow for more boost, not less flow. I only added the other stuff because Dave was joking around with me about mine. I don't know what stock boost is, but I wouldn't think it would be much more than that. I was thinking it was about fourteen pounds, but I couldn't swear to it.
You can buy a manual boost controller fairly cheap and it will help you boost quicker and more acurately.

 

[Nalleywhacker]

no, you need more flow for more boost, not less flow. I only added the other stuff because Dave was joking around with me about mine. I don't know what stock boost is, but I wouldn't think it would be much more than that. I was thinking it was about fourteen pounds, but I couldn't swear to it.
You can buy a manual boost controller fairly cheap and it will help you boost quicker and more acurately.

i guess i didnt make this clear, iam not trying to run more boost iam trying to run less! i just got back from driving it with the silencer and it boosted to 14psi and is holding and not cutting out. now thats still more than the 12psi it was holding at when i got the car. i guess my question now is at 14psi with stock injectors at stock fuel pressure iam i running to lean or iam i ok?

 

[suprahero]

I have no way of telling if your car is running lean or not. You can install a wideband to tell or you can pull one of your plugs out and inspect it. If it's really white, then it's too lean. Does it spit and sputter any? When it runs lean, it will do this sometimes as well. Good luck.

 

[Nalleywhacker]

I have no way of telling if your car is running lean or not. You can install a wideband to tell or you can pull one of your plugs out and inspect it. If it's really white, then it's too lean. Does it spit and sputter any? When it runs lean, it will do this sometimes as well. Good luck.

yeah i was just wonding if anyone knew if 14psi on stock everything would be lean, ill be getting a wideband soon so that will solve that. and no spits or sputters, i do get some smoke out the tail when stopped after some hard driving but iam thinking thats the crappy stock twins. thanks for the help jay.

Nathan.

 

[Frankenstien]

Just in case you haven't found out yet, stock boost on a 1JZ is 12psi. Or if you want to get technical, 11.8psi.

 

[big yoggz]

what is the fuel cut on a stock 1jz?

 

[JoeSupra]

around 14 psi