A month ago i replaced the upper intake plenum now im using alot of gas on my most recent fill up ,, is it a vaccum problem or a fuel injector o ring problem ,, if its vaccum where do u get the molded rubber elbows ond the one molded piece that has 3 ports ?
An expert who has achieved level 3 by getting 1000 points
An expert that got 10 achievements.
An expert that got 5 achievements.
An expert whose answer got voted for 100 times.
Re: excessive fuel use
It sounds like a vaccum leak thats when you use more fuel ... you can take starting fluid on the fittings and around intake ...listen to see if you hear the engine speed up,,,, if it dose thats your problem is .... dont get carried with the starting fluid ..just a little will work ..if it the rubber parts you can try autozone but probaly GM dealer part hopes this helps
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need. goodluck!
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
You have a vaccum leak. Check to make sure that any hose you removed from the intake boot to the plenum have been replaced and that all the clamps are tight and that the boot did not fold over on you while replacing that boot (its happened to me on several occasions). The more than likely culprit is the upper plenum gasket. After you check to make sure all of the hoses are connected and the intake boot is solid, you'll need to remove the upper plenum again to make sure the gasket is still in one piece and that no other debris has been trapped in between the sealing surfaces. The high rpms is due to the engine trying to compensate the amount of fuel to the amount of excessive air going to the engine. I'm a smoker and have actually had luck puffing on a cigarette and blowing alot of smoke into the intake boot until I see where the smoke comes out. But you definately have some kind of vaccum leak somewhere.
The upper intake plenum is leaking coolant into the cylinder heads. The head gaskets on this motor are awesome. So, chances are it's the upper intake plenum. You can check this, by removing the vacuum hose that runs between the upper plenum and the brake booster. Stick your finger in and try to touch the top of the lower intake manifold. If your finger is wet it the upper plenum. You might as well replace the lower intake gasket while you're performing this work because they are prone to failure also. Use a shop vac to pull any coolant out of the cylinder heads. Get brand new spark plugs because the old ones are probably fouled. Once you get the plenum and gaskets replaced, remove your fuel pump relay and leave the spark plugs out and turn the engine over repeatedly for about 10 seconds to push any excess coolant out of the cylinder heads. Then, put the spark plugs in and turn the engine over for 10 seconds again. This will burn excess fuel as coolant out. Then, replace the fuel pump relay to allow fuel to be pumped into the heads. Car will smoke for a few when it fires up, but will clear out quickly. CHANGE THE OIL! Twice within a week if possible.
Exactly what is the wrong? Need the part? Need to know torque adjust or porcedure to take off? For 1994 Pontiac Grand Am 3.1L SFI OHV 6cyl check this procedure for Intake Manifold... (see Figure 14) The 3.1L engine is equipped with upper and lower intake manifolds.
The upper intake manifold is also known as the intake manifold plenum.
The fuel system is under pressure and must be properly relieved
before disconnecting the fuel lines. Failure to properly relieve the
fuel system pressure can lead to personal injury and component damage.
Relieve the fuel system pressure.
Disconnect the negative battery cable.
Remove top half of the air cleaner assembly and throttle body duct.
Drain and recycle the engine coolant.
Disconnect the EGR pipe from exhaust manifold.
Remove the serpentine belt.
Remove the brake vacuum pipe at the intake plenum.
Disconnect the control cables from the throttle body and intake plenum mounting bracket.
Remove the power steering lines at the alternator bracket.
Remove the alternator.
Label and disconnect the ignition wires from the spark plugs and wire retainers on the intake plenum.
Remove the ignition assembly and the EVAP canister purge solenoid together.
Fig. 14: View of the intake manifold and related components
Disconnect the upper engine wiring harness connectors at the following components:
Throttle Position Sensor (TPS)
Idle Air Control (IAC)
Coolant temperature sensor
Manifold Absolute Pressure (MAP) sensor
Camshaft Position (CMP) sensor
Tag and disconnect the vacuum lines from the following components:
Fuel pressure regulator
Disconnect the MAP sensor from upper intake manifold.
Remove the upper intake plenum mounting bolts and lift off the plenum.
Disconnect the fuel lines from the fuel rail and bracket.
Install engine support fixture special tool J 28467-A or an equivalent.
Remove the right side engine mount.
Remove the power steering mounting bolts and support the pump out of the way without disconnecting the power steering lines.
Disconnect the coolant inlet pipe from the outlet housing.
Remove the coolant bypass hose from the water pump and the cylinder head.
Disconnect the upper radiator hose at thermostat housing.
Remove the thermostat housing.
Remove both rocker arm covers.
Remove the lower intake manifold bolts. Make sure the washers on
the four center bolts are installed in their original locations.
When removing the valve train components they should be kept in order for installation the original locations.
Remove the rocker arm retaining nuts or bolts and extract the rocker arms and pushrods.
Remove the intake manifold from the engine. Remove and discard the gasket.
Using a suitable scraper, clean gasket material from all mating
surfaces. Remove all excess RTV sealant from front and rear ridges of
Place a 0.12 inch (3mm) bead of RTV, on each ridge, where the front and rear of the intake manifold contact the block.
Using a new gasket, place the intake manifold on the engine.
Install the pushrods in their original locations. Coat the pushrods with prelube.
The intake pushrods are marked yellow (5
/4 inch long) and the exhaust are green (6 inches long).
Make sure the pushrods are properly seated in the valve lifters and
Position the rocker arms in there original locations and tighten
to specifications. Refer to the procedure earlier in this section.
Install lower the intake manifold attaching bolts. Apply sealant
12345739 (or equivalent thread locking compound) to the threads of
bolts. Tighten the vertical bolts first then the diagonal bolts to 115
inch lbs. (13 Nm).
Install the front rocker arm cover.
Install the thermostat housing.
Connect the upper radiator hose to the thermostat housing.
Fasten the coolant inlet pipe to thermostat housing.
Connect coolant bypass pipe at the water pump and cylinder head.
Install the power steering pump in the mounting bracket.
Loosely install the serpentine belt.
Connect the right side engine mount.
Remove the special engine support tool.
Fasten the fuel lines to fuel rail and bracket.
Install the upper intake manifold and tighten the mounting bolts to 18 ft. lbs. (25 Nm).
Install the MAP sensor.
Connect the upper engine wiring harness connectors to the related components removed earlier.
Connect the vacuum lines to the PCV, vacuum modulator and fuel pressure regulator.
Install the EVAP canister purge solenoid and ignition assembly.
Install the alternator assembly.
Connect the power steering line to the alternator bracket.
Install the serpentine belt.
Connect the spark plug wires to the spark plugs and intake plenum wire retainer.
Install the EGR pipe to the exhaust manifold.
Attach the control cables to the throttle body lever and upper intake plenum mounting bracket.
Install air intake assembly and top half of the air cleaner assembly.
Install the brake vacuum pipe.
Fill the cooling system.
Connect the negative battery cable, then start the vehicle and verify that there are no leaks.
An EGR that is stuck opencan very well cause the symptom you are decribing, including surging at idle and poor acceleration.
Failure of GM EGR Valves is quite rare.
A common problem on the 4.3L Vortec engines is failure of the Central Multiport Injection Assembly located between the plastic upper intake plenum and the lower intake manifold.
Sometimes failure of injector lines and/or the fuel pressure regulator (Part of the MFI Assembly) will cause fuel to spill into the upper plenum area. This can dislodge carbon deposits in the upper plenum which then get stuck in the EGR Valve and cause the symptoms that you are describing. The EGR Valve can be removed and cleaned. Replacement is not usually necessary.
Ido recommend replacement of the injector assembly however.
check out this solution page for more info regarding this.
You may have a ruptured diafram in the fuel pressure regulator which is putting unmetered fuel in the vacuum/intake system. It is located underneath the upper plenum. If you remove the vacuum hose going to it and fuel comes out, it is defective. You can find the hose diagram for the car on the hood or radiator core support to know which hose it is.
The upper intake has a egr port right next to a coolant port, the egr is exhaust gas that is recyled into the intake for emission control. On a long trip the exhaust burns a hole between the two ports causing your problem. Pretty common on the 3.8. My suggestion is to stop driving it until you have it repaired, reason being is the coolant can travel down the intake and fill up the cylinders. If that happens, worst case you can damage a rod, but you will be stranded.
you will have to remove upper intake plenum the black plastic part there is a o-ring around the area you are speaking of. now if this engine didn,t have the intake gaskets replaced before installing now would be good time because if you keep vehicle believe me you will have to do sooner or later these engines came with plastic intake gaskets that are notorious for leaking to do this you will njeed to remove both upper and lower intake manifolds I just started a job on 99 tahoe today before lunch and customer is driving tonight replaced upper and lower intake gaskets fel-pro makes updated gaskets for this engine that has thick metal shim and rubber gaskets a great improvement that ends this problem as for your vacuum leak at opening for fuel lines don,t see often but is possible hope this helps
CODE 174 IS BANK TWO FUEL SYSTEM LEAN.IF U HAD A FUEL PRESSURE ISSUE U WOULD HAVE A CODE 171 ALSO(BANK 1 LEAN)CK FOR A VACUUM LEAK AT THE INTAKE MANIFOLD GASKET(SPRAY CARB CLEANER WHERE MANIFOLD MEETS THE HEAD)IF THE IDLE PICKS UP THE GASKETS ARE BAD.SOMETIMES THE GASKETS GO BAD INTERNALLY.U CAN SPRAY CARB CLEANER IN TO THE OIL FILL HOLE.IF IDLE PICKS UP INTAKE GASKETS ARE BAD.GOOD LUCK
It sounds like one of your sensors (MAP or MAF)is not getting the needed vaccum when it's cold. I would recommend an upper intake flush. Most of your local shops know how to do this. It will clean the carbon out of the intake and open the vaccum ports to al the sensors.