question about boost cut Options

[toyotacrazy]

I have a blitz type R dual sbc. It has a built in boost limiter. I hit the factory boost cut of 14 psi and I want to eleminate it or raise it. Ive heard you can cap off the boost pressure sensor and plug the hose going to it and will eleminate boost cut. By doing this will my tvsv monitor still work? Im thinking the ecu uses that map sensor to control the tvsv. Im in the process of collecting the parts to raise my fuel cut with the homemade controller. thanks

This post has been edited by toyotacrazy: Jun 5, 2007 - 9:02 PM

[lagos]

how do you know its fuel cut that you are hitting?

[toyotacrazy]

how do you know its fuel cut that you are hitting?

Its like hitting a brick wall. It felt the same as the speed limiter at 130 mph. After the boost cut hits, my MIL is on and I cant boost past 1 psi until I cycle the key.

[lagos]

it could be knock response. the only way to know for sure is to check the ecu codes. if you hit fuel cut, there will be a code for it (34? i think?). if its just knock response, then there will be no code.

normally fuel cut happens at 12 or 16psi, depending on the year of your motor. thats why im thinking something else is going on.

[bodhi]

Not sure of your exact setup, but it sounds (and looks on your profile) like you have the 2nd gen setup. Do you have the 2nd gen ecu and cylinder head?
If so, you will not be running a map sensor, only an air flow meter (which i could see in one of your pics).
In terms of the boost cut, the tvsv is not linked to a map sensor, but a turbo pressure sensor, and is only active in 3rd, 4th & 5th gear. It's basically a open or closed valve which when open bleeds off about 3psi from the actuator. If you're running a boost controller, you should really block the vsv off as strictly speaking you have 2 controllers fighting each other for control. You might find that this results in boost spikes which are causing the over boost and fule cut. Try blocking the vsv off first by blocking both the pipe on the actuator and the pipe running to the vsv. This will also allow full boost in all gears.
Failing that, you can install a boost cut defencer which can be made quite easily which will mask the reading from the turbo pressure sensor so that you can run higher boost. Don't run more than 14PSI though unless you have a metal head gasket, otherwise it will fail fairly quickly.

Details on the vsv and how to block it off, and also how to make a Fuel cut defencer are on this website along with loads of other really useful info. www.gtfours.co.uk

Hope that helps
Chris

[toyotacrazy]

Not sure of your exact setup, but it sounds (and looks on your profile) like you have the 2nd gen setup. Do you have the 2nd gen ecu and cylinder head?
If so, you will not be running a map sensor, only an air flow meter (which i could see in one of your pics).
In terms of the boost cut, the tvsv is not linked to a map sensor, but a turbo pressure sensor, and is only active in 3rd, 4th & 5th gear. It's basically a open or closed valve which when open bleeds off about 3psi from the actuator. If you're running a boost controller, you should really block the vsv off as strictly speaking you have 2 controllers fighting each other for control. You might find that this results in boost spikes which are causing the over boost and fule cut. Try blocking the vsv off first by blocking both the pipe on the actuator and the pipe running to the vsv. This will also allow full boost in all gears.
Failing that, you can install a boost cut defencer which can be made quite easily which will mask the reading from the turbo pressure sensor so that you can run higher boost. Don't run more than 14PSI though unless you have a metal head gasket, otherwise it will fail fairly quickly.

Details on the vsv and how to block it off, and also how to make a Fuel cut defencer are on this website along with loads of other really useful info. www.gtfours.co.uk

Hope that helps
Chris

I have a 2nd gen. ecu and cyl. head. I dont think it knock responce. My tvsv monitors are green when it happens. It only happens at or around 1 bar. Power just shuts down. then like I said, I cant boost until I cycle the key, then the mil goes off and everything is back to normal. Ive already blocked off both ports to and from the tvsv.

[bodhi]

sounds like basic boost cut then, i'm not familiar with a tvsv monitor, but I can't imagine it will show anything if it is blocked off. make the FCD that you were on about and fit that to the ecu wiring. You can then trim the boost cut up to what you want. bear in mind though that with the standard ecu map and the standard 440cc injectors, you can't boost over 16PSI as you will begin to under fuel because the fuel map does not go any further and your injector duty cycle will be getting close to max.

This post has been edited by bodhi: Jun 6, 2007 - 5:34 PM

[toyotacrazy]

sounds like basic boost cut then, i'm not familiar with a tvsv monitor, but I can't imagine it will show anything if it is blocked off. make the FCD that you were on about and fit that to the ecu wiring. You can then trim the boost cut up to what you want. bear in mind though that with the standard ecu map and the standard 440cc injectors, you can't boost over 16PSI as you will begin to under fuel because the fuel map does not go any further and your injector duty cycle will be getting close to max.

Im waiting on the resistors to come in for the fcd. Otherwise it would be done by now. I wanted to run 16-17psi max. The only reason Im going to run that high is I have a fmic and alcohol injection. I figure that if stock boost is 10-12, toyota probably designed it well enough to handle 16psi especially with the mods I have. Thanks for all your interest
-toyotacrazy

[lagos]

why dont you check your CEL codes? since you had funny issues with the tvsv... it would be good to just double check that you have the fc code. cause your the 1st guy i know of that got fc at 14psi of boost.

This post has been edited by lagos: Jun 6, 2007 - 5:59 PM

[toyotacrazy]

why dont you check your CEL codes? since you had funny issues with the tvsv... it would be good to just double check that you have the fc code. cause your the 1st guy i know of that got fc at 14psi of boost.

Sure enough, the only code I have is 34. where on the forum is the mil codes with a description?

[lagos]

http://celicatech.com/forums/showthread.php?t=10155

[toyotacrazy]

why dont you check your CEL codes? since you had funny issues with the tvsv... it would be good to just double check that you have the fc code. cause your the 1st guy i know of that got fc at 14psi of boost.

I hit fuel cut this morning at .96 bar=14 psi.
I wonder why my ecm is different?????

[lagos]

what boost gauge are you using? im willing to bet your gauge isn't reading correctly.

[toyotacrazy]

what boost gauge are you using? im willing to bet your gauge isn't reading correctly.

When my ractive boost gauge reads 12 psi. My blitz boost controller type R reads .96 bar or 14 psi.

This post has been edited by toyotacrazy: Jun 9, 2007 - 11:41 PM