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Vacuum line stalling engine when connected to nvld

2483 Views 48 Replies 5 Participants Last post by  Bob Lincoln
Does anyone know why when I connect the 2 vacuum lines 1 from plenum the other on to of throttle body the engine cuts off on idle.
Do these lines go to a vacuum pump? Defective?
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Discussion Starter · #4 ·
Does anyone know why when I connect the 2 vacuum lines 1 from plenum the other on to of throttle body the engine cuts off on idle.
Do these lines go to a vacuum pump? Defective?
Sorry I forgot it's the base model, non turbo 2003, it seems it goes to a vacuum pump, in a real awkward place below the breaker booster, I'm hoping it's not the pump. I did an engine swap, on a car that was not running.
I also came across a relay,/fuse yellow and orange in color, 3, pins that fell off and I cannot find where that plugs into, wondering if that had something to do with it
 

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Discussion Starter · #5 ·
As ImperialCrown stated we need to know specific make, model, year and engine configuarion, 4 cylinger, V6, V8, and some images of the vacuum lines in question to make a reasonable, accurate diagnosis.

Now if you wanted a "wild guess" I would say one of the suspect vacuum lines might be connected to the EGR valve. Fully activated EGR (exhaust gas recirculation) will stall an engine and stop it from idling. But again just a guess. Give more detailed information as requested.
I did change the egr valve, since the old one was broken, can I deactivate it
 

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Discussion Starter · #11 ·
Ufortunately some of the drawings in a factory service manual are mislabeled. In post #6 presented by ImperialCrown the trapezoid symbol that is labeled 2.7L would make you think that symbol represents the engine. It should be labeled as the vapor canister. See attached image.

View attachment 89124



The device that provides pumping action and applies a vacuum to the fuel tank and evaporative system is the purge solenoid that is mounted under the power brake booster. The NVLD device vents over pressure, cleansed air to the atmosphere and seals the tank under a vacuum. It is located along with the vapor canister at the fuel tank.
The vacuum houses go to this device, right?
 

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Discussion Starter · #13 ·
As ImperialCrown stated we need to know specific make, model, year and engine configuarion, 4 cylinger, V6, V8, and some images of the vacuum lines in question to make a reasonable, accurate diagnosis.

Now if you wanted a "wild guess" I would say one of the suspect vacuum lines might be connected to the EGR valve. Fully activated EGR (exhaust gas recirculation) will stall an engine and stop it from idling. But again just a guess. Give more detailed information as requested.
The 2003 does not have egr valve?
 

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Discussion Starter · #15 ·
Standard 4 cylinder stalls on idle when pvc valve hose connected to plenum or the vacuum line on top of throttle body. Disconnecting either one did not stall.
This car does not have egr valve, seems the 2 vacuum hoses, one back of plenum and other on top of throttle body, goes back to the fuel line and the nvld canister.
Does anyone have ideas
 

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Discussion Starter · #19 ·
It is difficult to envision the dislodged. vacuum hoses on your vehicle without an image. If you can take a picture and post that would be helpful. Otherwise find the underhood vacuum diagram and connect lines as shown.

From a view into the engine compartment all you will see is the purge valve under the brake booster. There will be a vacuum hose from the purge valve that connects to a line under the body that runs to the vapor canister mounted on the fuel tank. The purge valve will have another port with a vacuum line that attaches somewhere on the intake plenum.

Follow the larger hose from the brake booster to the intake system. At the intake is there an open port with no vacuum hose attached? If YES this port with missing hose should have to be connected to the purge valve.

This connected vacuum line should agree with the underhood diagram. If the engine stalls at idle with this configuration, it is possible that the purge valve is stuck open. With a stuck open valve the engine is drawing in rich fuel vapors and the overly rich air-fuel ratio is causing engine stall. Just a guess on my part.
No hoses are missing, ask the hoses are connected you the correct ports , how can I test the purge valve
 

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Discussion Starter · #21 ·
It is difficult to envision the dislodged. vacuum hoses on your vehicle without an image. If you can take a picture and post that would be helpful. Otherwise find the underhood vacuum diagram and connect lines as shown.

From a view into the engine compartment all you will see is the purge valve under the brake booster. There will be a vacuum hose from the purge valve that connects to a line under the body that runs to the vapor canister mounted on the fuel tank. The purge valve will have another port with a vacuum line that attaches somewhere on the intake plenum.

Follow the larger hose from the brake booster to the intake system. At the intake is there an open port with no vacuum hose attached? If YES this port with missing hose should have to be connected to the purge valve.

This connected vacuum line should agree with the underhood diagram. If the engine stalls at idle with this configuration, it is possible that the purge valve is stuck open. With a stuck open valve the engine is drawing in rich fuel vapors and the overly rich air-fuel ratio is causing engine stall. Just a guess on my part.
Here the diagram attached
 

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Discussion Starter · #22 ·
Start engine and let it idle. Remove vacuum hose connected to vapor canister port on purge solenoid valve. Apply piece of paper to uncovered port on valve. There should be no vacuum at port trying to attract paper with engine idling. If vacuum is found, the purge valve is leaking and needs to be replaced. See attached image.

View attachment 89141
Ok thanks, I put another used purge valve and it's going the same, I'll buy a new one
 

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Discussion Starter · #24 ·
It may not need a purge valve. I've had purge valves stuck open because a piece of charcoal from the charcoal canister got sucked up into it. Can you blow through the valve?
If the canister is loaded with raw fuel, it can allow for a rich mixture. Do you smell a strong odor of fuel?
Either condition may or may not cause a stall. Always diagnose first.
Cannot blow through the tube, this tube goes to the valve below the brake booster, in a real awkward place, I guess this is the canister. The purge valve on the throttle body is ok, since I changed that already
 

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Discussion Starter · #27 ·
As ImperialCrown stated in post #26 the device with vacuum hose below the power brake booster is the purge valve. It is not the vapor canister which is located at the rear alongside the fuel tank. Please post a picture of the attachment of the vacuum hose at the throttle body and the device you changed at the throttle body.



Please post a picture of this "relay / fuse yellow and orange in color 3 pins that fell off ". Identify any wire colors attached including secondary tracer color wire.
I changed the purge valve below the booster, it's still doing that, does the ac lines have anything you do with this. Ok had found a couple of loose ac pipes
 

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Discussion Starter · #28 ·
As ImperialCrown stated we need to know specific make, model, year and engine configuarion, 4 cylinger, V6, V8, and some images of the vacuum lines in question to make a reasonable, accurate diagnosis.

Now if you wanted a "wild guess" I would say one of the suspect vacuum lines might be connected to the EGR valve. Fully activated EGR (exhaust gas recirculation) will stall an engine and stop it from idling. But again just a guess. Give more detailed information as requested.
The 2003 does not justice egr valve
Ok thanks, I put another used purge valve and it's going the same, I'll buy a new one
Are you talking about purge valve in the fuel tank or below the brake booster
 

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Discussion Starter · #29 ·
I give up, all the vacuum lines are connected correctly, no kinks or tears, installed new nvld valve and engine still stalling, even changed purge valve on throttle body.

Could it be the other valve on the tank, Is there a relay or fuse somewhere that can be causing this, did the ac lines have something to do with these vacuum lines. Any ideas, thanks
 

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Discussion Starter · #32 ·
The purge valve is NOT located on the throttle body. What device have you changed on the throttle body? Have you changed the throttle position sensor? Idle air control? See attached image.
View attachment 89212



Air conditioning refrigerant lines would not cause this issue.



I would think that even if the vapor canister is flooded with liquid fuel and the purge valve is sealing correctly, no liquid and / or vapor should be entering the induction system through the purge valve???

Have you check the PCV (positive crankcase ventilation valve)? If it is stuck open it would allow excess air and crankcase vapors to enter the induction system and cause a stall at idle. Remove the hose at the PCV valve and seal the end. Does the engine continue to stall? Remove the PCV valve from the camshaft cover. You should be able to shake and hear it rattle. If no noise or movement detected it is stuck and needs replacement. See attached image.
View attachment 89211
I changed the throttle position sensor
 

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Discussion Starter · #33 ·
Start engine and let it idle. Remove vacuum hose connected to vapor canister port on purge solenoid valve. Apply piece of paper to uncovered port on valve. There should be no vacuum at port trying to attract paper with engine idling. If vacuum is found, the purge valve is leaking and needs to be replaced. See attached image.

View attachment 89141
When u say purge valve leaking, r u referring to the one at the back on has tank or the one below the brake booster, nvld valve?
 

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Discussion Starter · #35 ·
There is only one purge valve. It is the one under the brake booster.
(an undercar image looking up at it):



The NVLD is at the rear of the car on the fuel tank next to the canister.
Thanks so I changed the purge valve, do I think it could be the nvld then. Also do u recognize this fuse/relay it feel off somewhere from engine compartment
 
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