car is running 14psi cat back system chip indiction kit . just came make car a boot from the rite foot and I herd a loud pop sound the car when from 14 psi to what looks like 5 or 6 psi on my boost gauge ? so were do I start what is has likely happened

What ecu do you have ?

have not looked don't have consult

You can't run 14psi on stock ecu

ecu is chiped not stock

Your car now got into safety boost. Might be knock sensor

it made a loud pop then went in to safety boost not sure if the loud pop came from the exhurst or not. if its triggerd a code will that code still be there say in the morn or would it llike reset once you turn the car off if that makes sence

or the pop could of been a boost pipe bursting or coming undone ...

sounded like a back fire pop kind of noise

Edited November 28, 201312 yr by dan300zx

can a back fire in the system be picked up by the knock sonsor and trigger safety boost

prop a pipe of some were as you herd the pope and the speed you were potentaly traverling under 14psi the poping noise proberly seemed like it came from the back as your ears already passed the noise at 90 mph. your now in safety mode.

or the pop could of been a boost pipe bursting or coming undone ...

 

That's my guess as well....:oops:

going to see if there are any codes now will report back in a min

code is 55 so no codes to read if the car was put into safety mode by the knock sensor would there be a code

Yes, mine showed a code. It was also intermittent for a bit and would leave safety mode if you cycled the ignition. Until it stopped working entirely then it stayed in safety boost.

Reading the op again it does sound like a pipe popping off. I find it hard to pinpoint where sounds come from sometimes. But if a pipe had popped off, it would run like a pig. I would expect a hiss or a woosh as it leaks.

 

My Capri once popped and lost boost in a really weird way. It split the boost pipe going into the engine about an inch down the side between the jubilee clips. This was like a self healing wound that was almost invisible and didn't splay open till about 4 psi of boost then it opened like an eye and totally lost boost. Was a total sod to find.

this happened last nite just started the car and went out it boosting back up to 14 psi again now so does that tell us the knock sensor triped the safety boost

Bit beyond my zed knowledge but I thought, knock sensor operation shows a persistent code (34???) but it could be a slightly A-typical knock sensor thing.

 

The knock sensor will put the car in safety boost if:

 

1) It hears knock below about 3500rpm and sends a signal to the ECU for the remainder of the drive to be in safety boost.

 

2 It stops working and the ECU does not hear some sort of "all is well" signal and so it fails safe and goes into safety boost.

 

My bypass simulates that "everything is ok" signal for the ECU to stop it failing safe.

just rung a tuner I know he says a miss fire or back fire could trigger the safety boost and I did here a pop bang at the time it happened

I suppose that however unlikely a lot of things could cause it, because it works by listening for the pinking. So if you hit your exhaust with a spanner and it was the same sort of frequency of 'ping' that it listens for then it could do it. Perhaps the code 34 (that I had) is "Knock sensor has died" rather than "Oh shit I heard knock".

You can't run 14psi on stock ecu

 

Yes you can. It's not ideal but doable:

 

http://www.300zx.co.uk/forums/showthread.php?173357-Aftermarket-Chip-Analysis-amp-Comparison&p=1778343&viewfull=1#post1778343

Deffo sounds like a pipe has blown off

no pipes are fine boost is back to 14psi after leaving the car over nite