Hilux 4x4 Forum

What do these two vacuum pipes do on a 2700i engine? On HoundDog, one pipe was loose, while the other one going to a solenoid or valve, was missing entirely. There is such a myriad of hoses in these engines that I only found out that there was a pipe missing when I compared HounDog's engine to White Fang's engine.

HoundDog went like a bat out of that hot place when the chip was in, but it would not idle, specifically if the A/C was on. Removing the chip and blanking its plug off with a Dastek plug cured the idling problem, albeit at a loss of low-down revs. Since replacing the hoses though, I have not yet tried the chip again.


Click on the pics to enlarge them and read the text.


-F_D

I'm not familiar with the 2.7i at all, butit looks like you've got it right, Eric. The 'S' shaped pipe goes to the fuel rail pressure control valve and to my mind, assists to raise the pressure at revs when the fuel demand is higher. The other looks like it's hooked up to a vacuum reservoir for the brake booster, but I'm not sure what the solenoid control valve is for (maybe to open / close vacuum from the intake to regulate a more even vacuum level in the reservoir throughout the rev range.

The pipe on the left supplies vacuum to the fuel pressure regulator - At idle when engine vacuum is high, it opens the valve lowering fuel pressure. At higher RPM's when engine vacuum is low, the valve closes increasing fuel pressure.

The pipe on the right hand side feed the fuel vapor from the fuel tank that would leak into the air back in the intake to be burnt by the engine, which is why the 2.7 does not have a breather - it is a closed system. Operation below:

"Operation

The evaporative emission control system prevents the release of unburned hydrocarbons from the liquid gasoline vapor into the atmosphere. Evaporative fuel vapor from the tank is routed to the charcoal canister located in the engine compartment. The charcoal canister stores the vapor until the engine coolant reaches 54 degrees Celsius. When the engine coolant as above this temperature and the throttle is open, a vacuum switching valve opens to allow vapors trapped inside the canister to enter the intake manifold.

Fuel cap gasket
All vehicles require the replacement of the fuel filter cap gasket at 60 000 miles, to maintain the integrity of the evaporative emission control system. The gasket is important in sealing the filler neck and keeping the vapors from the tank routed through the vapor emission system."
(Chilton Toyota Pick-Ups/Land Cruiser/4Runner 1997-00 repair manual)

"Vapor pressure sensor
The vapor pressure sensor is used to monitor the fuel tank pressure or vacuum during the OBDII test portion for emissions integrity. This test scans the various sensors and output actuators to detect abnormal amounts of fuel vapors that may not be purging into the canister and/or the intake system for recycling. The vapor pressure helps the ECM monitor this pressure difference inside the tank.

Check
Poor Idling, stalling and poor drivability can be caused by an inoperative check valve, damaged canister, split or cracked hose or hoses or hoses connected to the wrong fittings. Check the fuel filler cap for damaged or deformed gasket"
(Haynes Repair Manual Toyota Tacoma, 4Runner & T100)"

Running with the pipes off should lean out the mixture as the amount of air measured by the MAF is more than the actual amount getting to the engine and as such the fuel ratio is less than what it should be. I hope the vheicle wasn't driven like this for a an extended time otherwise th valves may also have taken some heat.

Running with the pipes off should lean out the mixture as the amount of air measured by the MAF is more than the actual amount getting to the engine and as such the fuel ratio is less than what it should be. I hope the vehicle wasn't driven like this for a an extended time otherwise the valves may also have taken some heat.

Not by me, but I think Hennie did some mileage with it like this. Time will tell.

Thanks for the detailed explanation Willem, I have a better understanding of it all now (I think... takes a while for all this to soak in so early on a Sunday morning!).


-F_D

Wou nou net se vra vir Willem 3RZ, hy het daai tyd my ook gehalp met daai selfde pypies, maar hy was nou te vinneg vir my.

A bit OT.

Is it only the stealers that can use that black diagnostic plug.And what readings do they get from it?

The plug on the intake is the Toyota Diagnostic plug, you need to get their reader or count the pulses on two of the terminals with a light source and then hope you counted right and then deceipher the lot. I have the "codes" somewhere. You can do some stuff with it like run the fuel pump IIRC and you need to bridge two of the terminals to check the timing at idle etc.

Much better using OBDII port behind the dash above your clutch foot, you can get error codes and read realtime data like roadspeed, load, timing, fuel etc as an example.

I am busy getting an ELMSCAN5 - nice toy- with software you can read all or most of the sensors that supplies info to the ECU (but you cannot change timing and fuel values - before you get exited :problem: )

http://www.scantool.net/elmscan-5-usb.html

3RZ wrote:The plug on the intake is the Toyota Diagnostic plug, you need to get their reader or count the pulses on two of the terminals with a light source and then hope you counted right and then deceipher the lot. I have the "codes" somewhere. You can do some stuff with it like run the fuel pump IIRC and you need to bridge two of the terminals to check the timing at idle etc.

Much better using OBDII port behind the dash above your clutch foot, you can get error codes and read realtime data like roadspeed, load, timing, fuel etc as an example.

I am busy getting an ELMSCAN5 - nice toy- with software you can read all or most of the sensors that supplies info to the ECU (but you cannot change timing and fuel values - before you get exited :problem: )

http://www.scantool.net/elmscan-5-usb.html

Hi Willem.
This is quit an old post,but was wondering if you managed to get the ELMSCAN5 and if it is working.

I bought a similar one but it does not want to establish coms with the ECU, it doesn't work on my Wife's Renault either - not that that surprises me. I will let you know when I get something that works.

3RZ wrote:I bought a similar one but it does not want to establish coms with the ECU, it doesn't work on my Wife's Renault either - not that that surprises me. I will let you know when I get something that works.

Thanks Willem. i see they got a new one now. http://www.scantool.net/obdlink-sx.html" onclick="window.open(this.href);return false;

How difficult is it to get to the plug in the bakkie.Will like to see what mine looks like

Not difficult at all, above your left knee under the dash as you sit. Just take flashlight and have a look, std OBDII socket.

3RZ wrote:The pipe on the left supplies vacuum to the fuel pressure regulator - At idle when engine vacuum is high, it opens the valve lowering fuel pressure. At higher RPM's when engine vacuum is low, the valve closes increasing fuel pressure.

The pipe on the right hand side feed the fuel vapor from the fuel tank that would leak into the air back in the intake to be burnt by the engine, which is why the 2.7 does not have a breather - it is a closed system. Operation below:

"Operation

The evaporative emission control system prevents the release of unburned hydrocarbons from the liquid gasoline vapor into the atmosphere. Evaporative fuel vapor from the tank is routed to the charcoal canister located in the engine compartment. The charcoal canister stores the vapor until the engine coolant reaches 54 degrees Celsius. When the engine coolant as above this temperature and the throttle is open, a vacuum switching valve opens to allow vapors trapped inside the canister to enter the intake manifold.

Fuel cap gasket
All vehicles require the replacement of the fuel filter cap gasket at 60 000 miles, to maintain the integrity of the evaporative emission control system. The gasket is important in sealing the filler neck and keeping the vapors from the tank routed through the vapor emission system."
(Chilton Toyota Pick-Ups/Land Cruiser/4Runner 1997-00 repair manual)

"Vapor pressure sensor
The vapor pressure sensor is used to monitor the fuel tank pressure or vacuum during the OBDII test portion for emissions integrity. This test scans the various sensors and output actuators to detect abnormal amounts of fuel vapors that may not be purging into the canister and/or the intake system for recycling. The vapor pressure helps the ECM monitor this pressure difference inside the tank.

Check
Poor Idling, stalling and poor drivability can be caused by an inoperative check valve, damaged canister, split or cracked hose or hoses or hoses connected to the wrong fittings. Check the fuel filler cap for damaged or deformed gasket"
(Haynes Repair Manual Toyota Tacoma, 4Runner & T100)"

Running with the pipes off should lean out the mixture as the amount of air measured by the MAF is more than the actual amount getting to the engine and as such the fuel ratio is less than what it should be. I hope the vheicle wasn't driven like this for a an extended time otherwise th valves may also have taken some heat.

Hi I hope anybody can help. I have a problem on my 2.7i IFS when standing in the sun it sometimes have difficulty in starting (and when it does it idles rough or doesn't want to pick-up rpms) and the engine warning light comes on (Which then disappear after about 10-20 mins when driving). This only happens when standing in the sun :evil: After reading the above I suspect it might have something to do with some "gas/vapour" build up in the fuel system, which then affect one of the ECU sensors. I have a long range tank installed and there is a very "big" "hiss" sound when I open the fuel cap. Could this also be a problem with water contamination in the fuel tanks?

Hi, I know that this is an old post but I have a high idling problem. This all started after an engine rebuild, and I suspect the mechanic could have swapped or misplaced the vacuum hoses. I want to know where the hoses from underneath the canister goes. I have a 2.7 3rz engine exactly like the one displayed in those pictures.

I had a similar problem some years ago, these are the pictures I took at the time. Hope they help.

-F_D

Call me gobsmackeed!

I remembered about posting this many years ago but figured there is no way on this earth that I would ever have found the post. Perhaps I should have just scrolled up a bit...

-F_D

Thank you, do you have an idea where the hose underneath the canister goes? Because on my car, it is the one coming from the top of the throttle body, which I think is wrong.

That canister is the carbon canister which only get rid of the petrol fumes in the petrol tank and run them through the engine. Mine was disconnected it for a long time.

The first thing to start with is just plug all open vacuum holes. A short piece of pipe with a bolt in works well.

If the engine sucks air anywhere it will cause idling problems. Make sure there are no open pipes on the inlet manifold.

I just want to know where that hose goes sir. Thanks

Have a look at this link. There are a lot of images.

https://www.google.com/search?q=3RZ+vac ... yX9PT7qckM

If it is the metal pipe, the one goes to the fuel tank's breather and I think the other is just an open end breather for the canister. My vehicle not with me today.

Thank you sir. I will try it out.