Jump to content
SAU Community

Recommended Posts

the 'bunny hop's probably you hitting the overboost ignition cut

get one of those cheap pneumatic boost controllers (or splurge on a big dollar elec one if you prefer)

cheers mate, ye im actaully gonna get a boost controller in a few weeks it was meant to be done on the day i got my fmic but they had to leave it another day.

Link to comment
https://www.sau.com.au/forums/topic/177573-overboosting/#findComment-3242521
Share on other sites

Uhhh ok I dont see how a boost controller will help with overboosting if you dont have one on there already...

Firstly, what sort of car? How much is it overboosting by? And did you change anything else or only the FMIC?

A boost controller wont help at all if you have no boost control currently (ie its just the wastegate), as a boost controller simply cant make the wastegate open at any lower pressure than where the spring opens.

A bleed valve quite literally 'bleeds' some of the pressure so the wastegate doesnt see it, theres no way of making the wastegate see *more* pressure so that it opens sooner and therefore runs lower boost.

Link to comment
https://www.sau.com.au/forums/topic/177573-overboosting/#findComment-3242872
Share on other sites

Uhhh ok I dont see how a boost controller will help with overboosting if you dont have one on there already...

Firstly, what sort of car? How much is it overboosting by? And did you change anything else or only the FMIC?

A boost controller wont help at all if you have no boost control currently (ie its just the wastegate), as a boost controller simply cant make the wastegate open at any lower pressure than where the spring opens.

A bleed valve quite literally 'bleeds' some of the pressure so the wastegate doesnt see it, theres no way of making the wastegate see *more* pressure so that it opens sooner and therefore runs lower boost.

s15, dont know how much but all i know it passed the 1bar, i got zorst, pod, fmic, new clutch that has slipped but fixing it again.

If you've done a FMIC, make sure you have some sort of feed still going from a pressure source back to the wastegate.

Not pressure feed = no boost control

That would be my first place to look.

which vacume do i need to look at, dey all look like they r in place

Link to comment
https://www.sau.com.au/forums/topic/177573-overboosting/#findComment-3243296
Share on other sites

On the passenger side suspension tower, you will have a stock boost controller solenoid.

this will have hoses comming in and out of it.

one goes to the wastegate actuator and the other goes to the intercooler piping.

when stock, one of those pipes also has a tiny little restrictor in it to make the boost stay at 7psi.

so..

when you got a fmic installed, if they didn't connect the hose to the wastegate actuator or to the NEW intercooler pipe, you will have no boost control, therefore the wastegate will stay shut causing all the exhaust gases to go through the turbine wheel, making massive amounts of boost.

If it is all connected, they may have changed the hose or hoses from boost controller to new ones to fit the new piping and therefore the restrictor is gone and now you will have about 14-15psi if I remember correctly on my old S14..

so in a way, a new boost controller will solve your problem..

Link to comment
https://www.sau.com.au/forums/topic/177573-overboosting/#findComment-3243834
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I hope one day I can do it like you. Your engine looks great.
    • If there's nothing else I can do I'll probably do something like that Someone on the internet said that ca20s and ca18 engine blocks are the same and that you can use a ca20 engine block and put ca18det parts to make a ca20det Do you think this is possible or will it damage the engine?
    • Yeah, I did some research and found out that some things are different.
    • Makes sense, thanks! Consider me very impressed. And I very much appreciate the effort in documentating all of it. You'd be surprised, or maybe not, how many people this reaches who search for things online. Anyways, I shall continue to read all of it, understand maybe a quarter, and hope that some of it sticks if I ever end up in a situation where it's relevant
    • 'Did' work on them is more accurate ~ on the R31 Skyline forum, you can spot me as 'Solder'... I've written quite a bit about the 4R01 boxes there, and I ended up reverse-engineering the older TCU type operations, so we could fudge a custom TCU to pull off other tricks...and like all things, when you do it a lot, see the failure patterns, have to find parts etc etc, your head ends up filled with whys and wherefores... there was a reason Nissan went with these in more than 60models over 16+ years... all in all, the JR401E based design is an interesting study, as Nissan changed things over the years in a never ending battle against them lunching on themselves <grin>...by the time the RE4R01A rev.C came out (often referred to as RE4R01B), they'd more or less perfected the design...  
×
×
  • Create New...