fuel regulator vacuum pipe jspec

Hey

Was at my first track day today, lost all power on the straight , over fueling (black smoke) big thanks to colin in ssi for the help over the phone; knew what the issue was straight away!

I have two vacuum pipes going from the map sensor, one of the pipes is easy accesible on the fuel regulator on top of the intake but the second disappears over the intake and disappears somewhete deep in the block

I cannot see where it goes, does anybody have the schematic or know what it is iff?

I have it bypassed in the interim so i could get home

Bump

Is it an intake off to get at the vacuum pipes, can touch them with my fingers but cannot feel any tears or loose

The one from the map sensor goes between the intake and cam cover , loops down into a metal pipe which splits into two vacuum pipes near the rear firewall

Not too sure what they are for as she seems to run ok without it connected

It should go straight to the black plastic outlet on the intake manifold, right by the MAP sensor. It's a dampened vac reference.

It should go straight to the black plastic outlet on the intake manifold, right by the MAP sensor. It's a dampened vac reference.

Thanks Ian , I followed the vac pipe from the Map Sensor to the steel pipe which splits into two Vacuum pipes to the FP vsv

I managed to get a pic of the FP vsv ; so I think one of the pipes has popped off the FP vsv , just need to see if I can find it later

from the pic Looks like it is under the intake, I presume I should be able to feel it with my fingers ; I dont have a ramp so will be going in from the top deck ; so far I cannot feel any splits of loose vacuum lines

Please ignore the disconnected yellow pipe in the pic, I just hook the fuel regulator to the Mapsensor and bypassed the FP vsv vacuum pipe so I could get home

FP vsv

That's an emissions/charcoal canister VSV from what I recall, not fuel pressure, I think only the VVTi had an FP VSV.

Your photo shows things set up as they should be. The black plastic outlet runs the MAP sensor and the FPR, and that's all it should run. Anything needing a damped output like that can go onto it (my GReddy MAP sensor is also plumbed into it, but not my BOV etc) but the less the better, as you can lunch your engine if the hose pops off one of the links in the chain at the wrong time.

As to what that hose is plumbed into, it's a stock hose, and I'm pretty sure one should be there, but I can't recall what it's for

Found an old piccy, looks like it's supposed to go onto the undampened nipple that your blue hose is on instead.

Check out this:

http://www.mkivsupra.net/vbb/attachment.php?attachmentid=13939&d=1112558977

From here:

http://www.mkivsupra.net/vbb/showthread.php?35925-Engine-component-locations

It's the idle air reference hose for the EVAP (emissions) system. So if you've disconnected the charcoal canister and bunged up any other ends then that hose can be removed.

Thanks Ian! Diagrams really Help, I was ready for the hammer yesterday! I had to have a popsicle to cool down ha ha

I have the Fuel Pressure reference hose only connected to the map sensor & boost controller via the Idle air reference hose intake input for EVAP system (Blue pipe in the pic) !

I disconnected the Idle air reference hose for EVAP system to get home!

With the Idle air reference hose for EVAP system connected she was overfueling alot and everytime you turn the key she would splutter and die.

I traced the Idle air reference hose for EVAP system down the intake to steel pipe that splits into two hoses, I ran my fingers along each hose and found no tears or loose connections.

The Blue hose you see above running from the Idle air reference hose for EVAP system is the vacuum hose for my boost controller,

1. So I presume if I re-connect her she will get the same symptoms? Overfuelling etc
   
2. 
   
3. Has something gone in the car to cause this? I cannot feel or see any issues with the hose itself?
   
4. 
   
5. Not 100% sure what I need to do to fix it? Sorry!
   

Re-plumbed in the Idle air reference hose for EVAP system; Engine light and she smells of overfueling

Error codes

31 -- Air flow meter Circuit short

34 -- Turbo Pressure Malfunction;short in VSV or waste Gate Circuit

I disconnected the Idle air reference hose for EVAP system and Engine light is gone, she sounds OK ; no strong petrol fumes from exhaust

Obviously something is amiss in the EVAP System; what is the best approach to take?

By-pass the system? I cannot see any obvious loose or worn connection ; to be honest all the pipes look 19 years old; its hard to tell what is causing the issue.

I looked at the MKIV article on how to bypass the Charcoal canister but it is pants , anybody have a decent How to Do?

thanks

Those are odd error codes to get when moving vacuum pipes around - those are electrical circuit codes, indicating a short or broken connection. Losing the MAP sensor would result in overfuelling as you describe, it's possible that the wiring is bad around the sensor plug, and the act of plugging/unplugging the EVAP hose from the manifold disturbed the wiring enough to fix/break the connection. Try running the car and moving the MAP sensor connector and wiring around, see if it causes the problem again.

I traced the Idle air reference hose for EVAP system down the intake to steel pipe that splits into two hoses, I ran my fingers along each hose and found no tears or loose connections.

Is that a steel pipe underneath the manifold or are you talking about the "h" shaped pipe that goes off to the FPR and the MAP sensor?

Also, I thought your EVAP system is already disconnected from the picture you posted up in post 6? Or is that not a photo of your car?

 

 

Is that a steel pipe underneath the manifold or are you talking about the "h" shaped pipe that goes off to the FPR and the MAP sensor?

 

Also, I thought your EVAP system is already disconnected from the picture you posted up in post 6? Or is that not a photo of your car?

Sorry for the confusion Ian

The Idle air reference hose goes down between the Cam cover and the Intake mainfold to a steel pipe , he feel like a "h" shaped pipe alright(I cannot see it as it is under the manifold) ;then the "h" shaped pipe goes off to the FPR

I reconnected the EVAP system Last nite (Idle air reference hose) ; just to try repro the steps and to see if I could generate the issue again ; I also noticed an old pipe in the EVAP system I replaced (Hairline cracks on the ends; pipe is over near the clutch resevoir , off the piping along the rear of the Firewall) but the issue was still present. so I disconnected the Idle air reference hose again after I captured the engine codes**.

**At the track day the engine light did not come on , when the issue first arose; after I re-connected the Idle air reference hose last nite & replaced the old hose , the engine ight came on.

Photo above is of my car as of now

Blue Hose , is the hose I replaced

Current Setup

Idle air reference hose Output

• Yellow hose is Defi Boost Guage
  
• Blue Hose is Boost controller
  
• Idle air reference hose -- DISCONNECTED
  

Fuel pressure Reference Hose (Blue ) is between the MAP sensor and the Fuel pressure Regulator

Okay, what you should have is this (using the picture I linked to earlier):

The Manifold Pressure reference outlet (the black plastic nipple just under the MAP sensor) should got to the h shaped steel pipe, and from there go to 1) the MAP sensor and 2) the fuel pressure regulator (FPR). Nothing else should be t'd into this.

The idle air reference hose outlet (a simple nipple next to the black plastic one) can go off to your boost controller.

Get it set up like that and see how it behaves. Take a piccy of it as well and post it up

Just seen the pics. That second one looks like it's plumbed in as I've just described, can you get a picture from straight overhead so I can see the two nipple coming from the manifold, like in the http://www.mkivsupra.net/vbb/attachment.php?attachmentid=13939&d=1112558977 picture?

Okay, what you should have is this (using the picture I linked to earlier):

 

The Manifold Pressure reference outlet (the black plastic nipple just under the MAP sensor) should got to the h shaped steel pipe, and from there go to 1) the MAP sensor and 2) the fuel pressure regulator (FPR). Nothing else should be t'd into this.

This is done! since Friday to get home

I replaced the Black (Fuel Pressure Ref hose) with a new Blue one as the black one was brittle from age

The idle air reference hose outlet (a simple nipple next to the black plastic one) can go off to your boost controller.

 

Get it set up like that and see how it behaves. Take a piccy of it as well and post it up

I had it setup like this on Friday at the track day to get home; just the boost controller running off the idle air reference hose outlet ; she appeared to run fine.

I also took her for a spin on saturday and she boosted as normal ( I didnt give her the full WOT but did go to 4K - 4200K rev's)

What I am more concerned about it is the reason behind the issue, should I just run with the idle air reference hose disconnected; surely just disconnecting it is masking an issue?

Also don't forget to try wiggling the MAP sensor wires while the engine is running, see if you can trigger the problem like that

Also don't forget to try wiggling the MAP sensor wires while the engine is running, see if you can trigger the problem like that

Will do thanks , and I will get you the overhead pic when I get home.

For argument sake if , she is running ok after I check the wiring ; will I just leave the Idle ref hose disconnected and forget about it because she is running ok?

What I am more concerned about it is the reason behind the issue, should I just run with the idle air reference hose disconnected; surely just disconnecting it is masking an issue?

Ok cool. So it runs just fine with the MAP and FPR stuff plumbed in to the plastic one, and the boost controller plumbed into the EVAP nipple. The stock hose that *should* be plumbed into the EVAP nipple is just hanging in the air unconnected to anything, right?

The failure mode is when you plumb the stock hose back into the EVAP nipple along with the boost controller? Then you get overfuelling and bad idle, right? And we aren't sure what the stock hose is hooked up to at the other end?

If any of that is wrong, please put me straight. Apologies if this is a frustrating process

Ok cool. So it runs just fine with the MAP and FPR stuff plumbed in to the plastic one, and the boost controller plumbed into the EVAP nipple. The stock hose that *should* be plumbed into the EVAP nipple is just hanging in the air unconnected to anything, right?

Correct!

The failure mode is when you plumb the stock hose back into the EVAP nipple along with the boost controller? Then you get overfuelling and bad idle, right? And we aren't sure what the stock hose is hooked up to at the other end?

Correct!

Thanks for all the help! I think we are getting somewhere!

Right, now we're on the same page, time you found out where the other end of that stock hose goes

An open-to-atmosphere hose attached to the plenum should just cause the idle to be a few hundred rpm higher really, as it sucks in a bit more air, so I'm intrigued to see how it could be affecting the fuelling like that.

Oh, one last thing, was that stock hose plumbed in before and during the track day, before the symptoms started?

Right, now we're on the same page, time you found out where the other end of that stock hose goes

The idle air reference hose, I traced down to a "h" Steel Pipe , the two hoses off the end of the "h" (from what I could feel , buried under the mainfold intake and I tried via under the car but the oil Relocation kist is in the way to see anything or get hand in there) go to a VSV (you can see the two imputs in the VSV in the pic);

Intially I taught a hose pipe popped off but they are connected plus I cannot feel any rips or tears on the pipes.

An open-to-atmosphere hose attached to the plenum should just cause the idle to be a few hundred rpm higher really, as it sucks in a bit more air, so I'm intrigued to see how it could be affecting the fuelling like that.

Diddo!

Oh, one last thing, was that stock hose plumbed in before and during the track day, before the symptoms started?

Yes , The idle air reference hose was plumbed in! But this is where it gets interesting.

It was plumbed in not via the Idle air ref hose outlet but via the MAP Sensor --> Fuel Regulator section!

The Defi guage and Boost controller was plumbed in via the The idle air reference outlet

OLD setup

• Boost controller was plumbed in via the MAP Sensor --> Fuel Regulator section (Garage who I got the car off & fitted the Boost controller did this)
  
• Defi Boost guage was plumbed into the The idle air reference outlet
  
• Idle air reference hose was plumbed into the The idle air reference outlet
  

Trackday setup

**My Defi was plugged into the The idle air reference outlet; due to an inaccurate reading between the Boost controller and Defi; I swapped them around. To run them off the same source to get an accurate reading on the two units

• Idle air reference hose was plumbed in via the MAP Sensor --> Fuel Regulator section
  
• Defi Boost guage was plumbed into the The idle air reference outlet
  
• Boost controller was plumbed into the The idle air reference outlet
  

Current setup

• Idle air reference hose DISCONNECTED
  
• Defi Boost guage is plumbed into the The idle air reference outlet
  
• Boost controller is plumbed into the The idle air reference outlet
  

Okay that stock hose from the EVAP reference goes to that VSV, and it switches to allow the engine to draw in petrol fumes from the charcoal canister into the plenum during idling. There is no way I can curently see that it could cause the problem you're experiencing. What is interesting, though, is that it should go straight to the VSV, and no tee off to anything else. So I'm wondering what the h pipe under the manifold is doing in that circuit. (I'm assuming it's not the same h pipe you described earlier as being above the manifold and feeding the FPR and MAP, as you've described it in a compeltely different position).

So finding out where both outputs of that h pipe go is your second step - the first is the MAP plug and wiring wiggle

-Ian

PS I've added a pic to show what the stock pressure system should look like and which bits we are looking at.

Okay that stock hose from the EVAP reference goes to that VSV, and it switches to allow the engine to draw in petrol fumes from the charcoal canister into the plenum during idling. There is no way I can curently see that it could cause the problem you're experiencing. What is interesting, though, is that it should go straight to the VSV, and no tee off to anything else. So I'm wondering what the h pipe under the manifold is doing in that circuit. (I'm assuming it's not the same h pipe you described earlier as being above the manifold and feeding the FPR and MAP, as you've described it in a compeltely different position).

 

So finding out where both outputs of that h pipe go is your second step - the first is the MAP plug and wiring wiggle

 

-Ian

 

PS I've added a pic to show what the stock pressure system should look like and which bits we are looking at.

Thanks Ian , will give it a go tonight

Triple check the h pipe under the manifold , but from what I remember the EVAP outlet Hose goes to the h pipe; the two hoses from the h pipe go to the VSV ; whick would mean , instead of one fo the hoses going to the check valve in your diagram it is get rerouted back to the EVAP outlet circuit

Reason behind thinking it was a hose pop-off is, the car started overfueling after I came off boost for a slow corner back onto the main straight; as soon as I tried to put the foot back in she started trying to die on rpm & overfueling. I was under the impression a MAP sensor will not just suddenly die, maybe the heat for the engine bay's morning session got to the MAP sensor.

But I was only doing about 5-6 laps and letting her cool down with the bonnet up for min 30-45 mins between. Then again she is near 20 years old and heat is what kills things.

Leave it with me! I am intrigued to what it is!