fuel rail pressure switch

[StevenS]

Please explain how higher rail pressures, higher boost pressure and more fuel into a combustion chamber is good for the motor and better then a factory setting?

X 2 x 3 and x 4 to that!!!

Raising the rail pressure doesn't always make you use more fuel.
At higher rail pressures the injectors atomise the fuel for more effective combustion. Obviously if you turn the rail pressure up TOO much you would risk doing damage to injection pump, injectors and or engine.

So obviously if you go crazy and load a wild tune then you will yes... Use more fuel and risk possible damage. But I was never talking about wild tunes I'm talking about a chip that you can have custom tuned, this gives the end user the option of choosing a conservative tune that is well within the limits of safe engine operations. For e.g I run a custom turn for touring with heavy loads that gives me a little more fuel and boost down lower in the rev range but at top end is very similar to factory settings.
When I'm heavily loaded I get better fuel economy and is more drivable.
So this is why its best to find a quality chip that can actually map the whole range and not just simply dump more fuel in as you put your foot down.

So along with secondary fuel filtration, blanked EGR and a list of other bits I 100% believe I've made my rig more reliable and efficient than if it was in stock form.

With this setup I just returned from a 39,000km trip around Aus without a single engine issue and returned an average fuel figure of 12.8 L/100. GVM of 3.1 t. Rolling on 32' km2's.

Anyway that's my say.. so take or leave it. Everyone has different requirements and setups so that's what's got to be considered before deciding to modify vehicles this way. If I was using my ute for general use than I probably couldn't see the value in using a chip because they already come out of the factory for general use.

Sorry for going off topic a bit.

For starters it's been pretty much accepted that blanking your EGR will do more harm than good. Fit a quality oil catch can instead.

Raising rail pressure WILL always use more fuel unless you completely custom tune everything - this means injector duration, rail pressure, boost etc. If you run a chip that only ups rail pressure and boost for example then you will use more fuel (more rail pressure at same injector open time means more fuel)

I think the claims of better fuel atomisation should be taken with a grain of salt - these fuel systems were designed to run at such high pressures to accomplish, oddly enough, good atomisation of the fuel. If Toyota believed they could achieve even more power/economy/efficiency by running a higher pressure they'd have designed their systems to do so.

I would be interested in how running a custom tune on a ute that was overloaded and working hard for super long distances could be considered within safe engine limits. Fuel economy doesn't always paint the full picture.

[srburnsy]

No worries mate.

[07luxyTD]

For starters it's been pretty much accepted that blanking your EGR will do more harm than good. Fit a quality oil catch can instead.

Raising rail pressure WILL always use more fuel unless you completely custom tune everything - this means injector duration, rail pressure, boost etc. If you run a chip that only ups rail pressure and boost for example then you will use more fuel (more rail pressure at same injector open time means more fuel)

I think the claims of better fuel atomisation should be taken with a grain of salt - these fuel systems were designed to run at such high pressures to accomplish, oddly enough, good atomisation of the fuel. If Toyota believed they could achieve even more power/economy/efficiency by running a higher pressure they'd have designed their systems to do so.

I would be interested in how running a custom tune on a ute that was overloaded and working hard for super long distances could be considered within safe engine limits. Fuel economy doesn't always paint the full picture.

X2 on that. You can atomise a 68 grade hydraulic oil at 3500 psi and get a diesel engine to run off it. These engines have been known to of running the common rail at 25,000psi. So i take it atomisation of the diesel in these engines is perfect already. Higher rail pressure with same injection length = more fuel in the chamber also more stress on the fuel pump. Ive got nothing against chipping an engine as long as its moderate and has a practical reason eg. running at full gvm.

[mattwhite]

Open a valve (injector) for x amount of time and get y amount of fuel.

Increase the pressure of the fuel and open the valve the same amount of time it simply has to pass more fuel.

[srburnsy]

Open a valve (injector) for x amount of time and get y amount of fuel.

Increase the pressure of the fuel and open the valve the same amount of time it simply has to pass more fuel.

Yep totally agree.
I guess the only way higher rail pressure could becomes more efficient on fuel usage is shorter duration of the injection cycle and better combustion?

[outbackjoe]

Any system or fuel saving device that claims "better combustion" etc you can automatically discount. There is no better combustion to be had in a modern engine. There are references out there indicating that generally less than 1% gains are available through better combustion since the combustion is already so good. Apart from that it's plain common sense - if the was an effective way to improve efficiency the vehicle manufacturers would exploit it. Chips just dump more fuel in and wear stuff out faster. Nothing more to it. No fancy buzz words can circumvent basic physics.

[07luxyTD]

hi all
i have a 2007 d4d hilux with a 2 3/4 exhaust and chipit modual.
today i was driving around town pulled in to get some diesel (light was on) went to pull
out of sevo and ute conked out and engine light came on and stayed on i got out and primed
the fuel system and all was good but engine light stayed on.
i took ute down to auto electrician mate and got him to put his scan gauge on and come up with
"fuel rail pressure switch" (didnt see what code was).
he cleared the code and engine was running fine then stopped at intersection and car splattered for
a second then ran fine (no engine light on).
headed home and got about 5km out of town when engine light came on and the car wouldnt go over
80km/hr.
the chip has been turned off the whole time (dual map switch).
has anyone had trouble with the fuel rail switch before is there anything i need to look at
any help would be greatly appreciated.

How'd you go with the origional problem? Are you able to get to the auto electricians, get the scan tool put on and see what the rail pressure is actually running at? Maybe something is playing up with your fuel pump. Have you checked your intank strainer?

[srburnsy]

Any system or fuel saving device that claims "better combustion" etc you can automatically discount. There is no better combustion to be had in a modern engine. There are references out there indicating that generally less than 1% gains are available through better combustion since the combustion is already so good. Apart from that it's plain common sense - if the was an effective way to improve efficiency the vehicle manufacturers would exploit it. Chips just dump more fuel in and wear stuff out faster. Nothing more to it. No fancy buzz words can circumvent basic physics.

Oh well it has worked for me so I guess we'll have to agree to disagree.
Not all vehicles come out of the factory the same... Some run better than others and use more or less fuel. The standard factory settings are just a compromises between cost and performance. I believe there's always a place for custom tuning in a standard vehicle to gain more power and efficiency. Do you really believe Toyota has individually tuned each vehicle to be as efficient as it can be.

Not all chips are dumb resistors that just dump fuel in. :roll:
But unfortunately there's heaps of those dumb chips out there waiting for those poor suckers that believe all their claims.

[outbackjoe]

Tuning for factory variations would involve, exactly half of the time, reducing rail pressure as the factory settings deviate randomly above or below the optimal solution. Chips don't do that. Chips perform blanket increase in rail pressure. That is not tuning. That is dumping more fuel in.

[obiee]

yeh had the scantool put on and rail pressure was 157630kpg max and 152970kpg at 2060 rpm
ever since i blew line back into tank etc i have done about 300km without a problem i just thought if
it was a blocked line or filter my filter light would of come on

hi all
i have a 2007 d4d hilux with a 2 3/4 exhaust and chipit modual.
today i was driving around town pulled in to get some diesel (light was on) went to pull
out of sevo and ute conked out and engine light came on and stayed on i got out and primed
the fuel system and all was good but engine light stayed on.
i took ute down to auto electrician mate and got him to put his scan gauge on and come up with
"fuel rail pressure switch" (didnt see what code was).
he cleared the code and engine was running fine then stopped at intersection and car splattered for
a second then ran fine (no engine light on).
headed home and got about 5km out of town when engine light came on and the car wouldnt go over
80km/hr.
the chip has been turned off the whole time (dual map switch).
has anyone had trouble with the fuel rail switch before is there anything i need to look at
any help would be greatly appreciated.

How'd you go with the origional problem? Are you able to get to the auto electricians, get the scan tool put on and see what the rail pressure is actually running at? Maybe something is playing up with your fuel pump. Have you checked your intank strainer?

[srburnsy]

Tuning for factory variations would involve, exactly half of the time, reducing rail pressure as the factory settings deviate randomly above or below the optimal solution. Chips don't do that. Chips perform blanket increase in rail pressure. That is not tuning. That is dumping more fuel in.

No that's not how the dom3 works.

As I said not all chips are the same.

[4sullima]

How does it work?

[07luxyTD]

yeh had the scantool put on and rail pressure was 157630kpg max and 152970kpg at 2060 rpm
ever since i blew line back into tank etc i have done about 300km without a problem i just thought if
it was a blocked line or filter my filter light would of come on

hi all
i have a 2007 d4d hilux with a 2 3/4 exhaust and chipit modual.
today i was driving around town pulled in to get some diesel (light was on) went to pull
out of sevo and ute conked out and engine light came on and stayed on i got out and primed
the fuel system and all was good but engine light stayed on.
i took ute down to auto electrician mate and got him to put his scan gauge on and come up with
"fuel rail pressure switch" (didnt see what code was).
he cleared the code and engine was running fine then stopped at intersection and car splattered for
a second then ran fine (no engine light on).
headed home and got about 5km out of town when engine light came on and the car wouldnt go over
80km/hr.
the chip has been turned off the whole time (dual map switch).
has anyone had trouble with the fuel rail switch before is there anything i need to look at
any help would be greatly appreciated.

How'd you go with the origional problem? Are you able to get to the auto electricians, get the scan tool put on and see what the rail pressure is actually running at? Maybe something is playing up with your fuel pump. Have you checked your intank strainer?

I think your best bet would be to now drop your tank and clean the pickup strainer. You may have a diesel bug in your tank

[BDG]

We've had this conversation before many times. Extra rail pressure does increase the wear inside the fuel system. We see injectors with high pressure erosion all the time. If someone doesn't mind a shorter life span for more power, thats fine. I fit into this category because i like power and am a bit immature in that respect LOL.

High rail pressure is an amazing thing. More pressure = better control, better power and better atomisation. =better fuel efficiency and better power and better emissions. My only arguement here is that this is the holy grail for vehicle manufacturers, so if they could do this from factory and maintain reasonable service intervals and block longevity (but everyone whinges about injector changes on standard systems) they would have been crazy not to run it higher. If Toyota, with all their R+D and with what they stood to gain out of doing it are not doing it, i assume its for good reason.

with the above stated, i run a chip, i like the power and understand that i will change injectors and turbochargers earlier, the bearings in the bottom end will wear-out faster (as will the rings) and also except that it is possible that if i don't keep a close eye on it, that splitting pistons and so on is somewhat likely 'if shit happens'. I'm fine with all of this because of the extra power (and it costs me a shite load less to sort this stuff).

Anyway, people with a chip would be FAR better leaving the effing pressure alone and dealing with just the duration and boost. (although all the points about turbo and block wear is still valid in this case)...