So i'm just about ready to make some more power. I have a list as long as my arm of upgrades including a Ct20B turbo, Wideband, Intercooler, Exhaust, Intake, Fuel Pump etc. (And of course upgraded brakes). Putting in my boost controller next week.
As far as I can tell from crawling though pages of forum threads with contradictory information, the Rev 2 has a MAP sensor which is used solely for the stock boost gauge and fuel cut. And disconnecting this MAP sensor will remove fuel cut so I don't have to go out and buy a fuel cut defender.
Is this correct?
Thanks
Fuel Cut Rev 2
Forum rules
Many subjects will have been discussed before. Please try the search function before starting a new thread.
Check in the Know Your 2 as the information you need may already be there.
Important ! - Please make your topic title as descriptive as possible . titles with just "help" generally dont get as many answers as a title that points to the problem
Many subjects will have been discussed before. Please try the search function before starting a new thread.
Check in the Know Your 2 as the information you need may already be there.
Important ! - Please make your topic title as descriptive as possible . titles with just "help" generally dont get as many answers as a title that points to the problem
-
Sonac
Topic author - Posts: 94
- Joined: 11/02/19 21:49
- Years of MR2 Ownership: 1
- MR2's Owned: 1
- Real Name: Mark
- Gender: Male
- Location: United Kingdom
-
MR2DI4
- Posts: 1474
- Joined: 20/04/11 23:18
- Current Model: None
- Years of MR2 Ownership: 23
- MR2's Owned: 1
- Real Name: 2023 i30N Hatch 6MT
- Gender: Male
- Location: Tauranga >>> New Zealand
- Been thanked: 1 time
- Contact:
Re: Fuel Cut Rev 2
There are two schools of thought on what the ECU does with the 0-5V signal from the TPS (Turbo Pressure Sensor)
Having a lifetime background in electronics down to component level repair and also having evaluated and logged the output of the TPS using a Voltmeter and a syringe with a fancy Fluke pressure calibrator I came to the conclusion that the output signal of the TPS was rather flash in terms of linearity and precision for it not to be used by the ECU for something other than the very crude stock boost guage and fuel cut.
The result was I designed and built my own FCD (Fuel Cut Defender) as part of also integrating a boost controlled switch to kick in the intercooler fan at boost levels over 5psi.
Yes you can simply remove the vac line from the TPS and your fuel cut is gone, the truth is nobody other than the Toyota design engineers know if this signal is used for anything other than the obvious. I went with preserving the signal exactly as intended right up to about 4.1V Volts (from memory I cannot remember exactly it was back in 2008 I did it) or just before fuel cut where it then "Clamps" the Voltage from going any higher.
Don't bother with the "Zener Diode" modification, it doesn't work in terms of preserving the signal. Its may work in terms of stopping fuel cut but it just stuffs the Voltage to do so. I won't go into why it doesn't work unless someone requests it.
Having a lifetime background in electronics down to component level repair and also having evaluated and logged the output of the TPS using a Voltmeter and a syringe with a fancy Fluke pressure calibrator I came to the conclusion that the output signal of the TPS was rather flash in terms of linearity and precision for it not to be used by the ECU for something other than the very crude stock boost guage and fuel cut.
The result was I designed and built my own FCD (Fuel Cut Defender) as part of also integrating a boost controlled switch to kick in the intercooler fan at boost levels over 5psi.
Yes you can simply remove the vac line from the TPS and your fuel cut is gone, the truth is nobody other than the Toyota design engineers know if this signal is used for anything other than the obvious. I went with preserving the signal exactly as intended right up to about 4.1V Volts (from memory I cannot remember exactly it was back in 2008 I did it) or just before fuel cut where it then "Clamps" the Voltage from going any higher.
Don't bother with the "Zener Diode" modification, it doesn't work in terms of preserving the signal. Its may work in terms of stopping fuel cut but it just stuffs the Voltage to do so. I won't go into why it doesn't work unless someone requests it.
-
benckj
- Posts: 326
- Joined: 05/04/06 1:00
- Years of MR2 Ownership: 5
- Gender: Male
- Location: Alexandra, New Zealand
- Been thanked: 4 times
Re: Fuel Cut Rev 2
Not sure what the TPS has to do with fuel cut as its driven from MAP sensor. From what I know you can block the vacuum line from MAP sensor to eliminate FC but you will also disable an important protection circuit. I’m not a fan of this mod as boost spike can certainly blow you HG, break rings or pop a piston. This is especially risky if fuel quality is poor.
-
MR2DI4
- Posts: 1474
- Joined: 20/04/11 23:18
- Current Model: None
- Years of MR2 Ownership: 23
- MR2's Owned: 1
- Real Name: 2023 i30N Hatch 6MT
- Gender: Male
- Location: Tauranga >>> New Zealand
- Been thanked: 1 time
- Contact:
Re: Fuel Cut Rev 2
Are we talking the AFM on the Rev 2 or are we talking MAF on the Rev 3 onwards ? The OP has the subject " Fuel cut Rev 2" so thats the AFM with the TPS giving the Fuel cut.
-
TonyleFrog
- Full Member
- Posts: 5436
- Joined: 29/07/06 1:00
- Current Model: None
- Years of MR2 Ownership: 16
- MR2's Owned: 6
- Real Name: Three guesses!
- Gender: Male
- Location: Kent
- Been thanked: 31 times
Re: Fuel Cut Rev 2
I'm quite surprised you've managed to get your terminology mixed up.
Rev2s have an Air Flow Meter (AFM). Its sensor measures Mass Air Flow (MAF).
Effectively the two acronyms refer to the same thing.
Rev3s don't measure that parameter. They have a Manifold Absolute Pressure (MAP) sensor.
AFM BGB page
If you're not living life on the edge, you're taking up too much room!
HM wrote: TonyleFrog aka "The Fog Penetrator"
HM wrote: TonyleFrog aka "The Fog Penetrator"
-
notroubleclubber
- Posts: 1029
- Joined: 31/07/09 7:36
- Years of MR2 Ownership: 8
- MR2's Owned: 3
- Real Name: Mark
- Gender: Male
Re: Fuel Cut Rev 2
Well done tony - i had no idea what mr2di4 is on about.
Rev 3 doesnt have a afm or maf (same thing). And whats the Throttle position sensor (TPS) got to do with fuel cut?...Nothing. I have no idea what hes going on about.
However Tony is correct in his post
Rev 3 doesnt have a afm or maf (same thing). And whats the Throttle position sensor (TPS) got to do with fuel cut?...Nothing. I have no idea what hes going on about.
However Tony is correct in his post
-
TonyleFrog
- Full Member
- Posts: 5436
- Joined: 29/07/06 1:00
- Current Model: None
- Years of MR2 Ownership: 16
- MR2's Owned: 6
- Real Name: Three guesses!
- Gender: Male
- Location: Kent
- Been thanked: 31 times
Re: Fuel Cut Rev 2
More terminological confusion I'm afraid. The acronym TPS can refer to two different things.
Throttle Position Sensor or Turbocharging Pressure Sensor.
http://k1ano.co.uk/boostcontrol/fcdintro.htm
Personally I wouldn't fit a FCD. Disabling an OEM safety feature isn't a great idea imo.
Get a proper aftermarket ECU and management system. A less expensive route than an engine rebuild.
Throttle Position Sensor or Turbocharging Pressure Sensor.
http://k1ano.co.uk/boostcontrol/fcdintro.htm
Personally I wouldn't fit a FCD. Disabling an OEM safety feature isn't a great idea imo.
Get a proper aftermarket ECU and management system. A less expensive route than an engine rebuild.
If you're not living life on the edge, you're taking up too much room!
HM wrote: TonyleFrog aka "The Fog Penetrator"
HM wrote: TonyleFrog aka "The Fog Penetrator"
-
jimGTS
- Posts: 2558
- Joined: 14/05/04 1:00
- Years of MR2 Ownership: 9
- MR2's Owned: 3
- Location: North Kent
Re: Fuel Cut Rev 2
If you got a decent boost controller with a boost cut limiter, then removing the fuel cut on a rev1/2 is fine.
However with a mbc or bleed valve I wouldn’t be as comfortable.
However with a mbc or bleed valve I wouldn’t be as comfortable.
-
MR2DI4
- Posts: 1474
- Joined: 20/04/11 23:18
- Current Model: None
- Years of MR2 Ownership: 23
- MR2's Owned: 1
- Real Name: 2023 i30N Hatch 6MT
- Gender: Male
- Location: Tauranga >>> New Zealand
- Been thanked: 1 time
- Contact:
Re: Fuel Cut Rev 2
Not getting anything mixed up.
Still awaiting the original poster to clarify what engine set-up he actually has in the car or post a picture.
My post is pretty clear if you read it properly.
It sounds like a Rev 2 that has just had a CT20b and other upgrades. The stock Rev 2 3SGTE doesn't have a MAP sensor it has the AFM.
Until he clarifies what he has with a picture of the engine bay its guess work.
Still awaiting the original poster to clarify what engine set-up he actually has in the car or post a picture.
My post is pretty clear if you read it properly.
It sounds like a Rev 2 that has just had a CT20b and other upgrades. The stock Rev 2 3SGTE doesn't have a MAP sensor it has the AFM.
Until he clarifies what he has with a picture of the engine bay its guess work.
-
Sonac
Topic author - Posts: 94
- Joined: 11/02/19 21:49
- Years of MR2 Ownership: 1
- MR2's Owned: 1
- Real Name: Mark
- Gender: Male
- Location: United Kingdom
Re: Fuel Cut Rev 2
It's a rev 2.MR2DI4 wrote: ↑06/04/19 23:26 Not getting anything mixed up.
Still awaiting the original poster to clarify what engine set-up he actually has in the car or post a picture.
My post is pretty clear if you read it properly.
It sounds like a Rev 2 that has just had a CT20b and other upgrades. The stock Rev 2 3SGTE doesn't have a MAP sensor it has the AFM.
Until he clarifies what he has with a picture of the engine bay its guess work.
-
MR2DI4
- Posts: 1474
- Joined: 20/04/11 23:18
- Current Model: None
- Years of MR2 Ownership: 23
- MR2's Owned: 1
- Real Name: 2023 i30N Hatch 6MT
- Gender: Male
- Location: Tauranga >>> New Zealand
- Been thanked: 1 time
- Contact:
Re: Fuel Cut Rev 2
So if the engine has the big flapper box on the air intake after the air filter called an AFM that Tony posted the picture above, then my earlier post applies. If you want to be very crude and remove the fuel cut you just pull the vac line from the TPS that is mounted on the firewall and block the tube, job done. I wouldn't recommend it, there are so many other things you need to modify and check and have a gauge for before you do that.
