3.4L and 3.1L V6 Engine Sensor Locations

Typical engine data sensor and control component locations on the GM 3.1 / 3.4 L V6 engine.
Click sensor description below image for sensor details..
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1. Fuel pressure regulator
2. Idle Air Control Motor (IAC)
3. Mass Airflow sensor (MAF)
4. Throttle Body
5. Throttle Position Sensor (TPS)
6. Fuel Injector
7. PCV Valve
8. Coolant Temp sensor (ECT)
9. Evap Purge Solenoid
10. EGR Valve
11. Intake Air Temp Sensor (IAT)
12. MAP sensor
• 3.1L / 3.4L Serpentine Belt Routing Diagram

Question: I have a 2001 Pontiac Grand Prix that stopped running, I have put a new fuel pump, and new computer box on it, but it still wont start. Can you help me,, please, it is driving crazy
 Answer: There are way too many things that can cause the car to stall and not start. Do you have spark, fuel pressure, injector pulse, theft or security light on dash, etc. You need to start by diagnosing the basics.

1994 Grand prix 6 cylinder engine. Car stared missing, was told it was EVAP purge solenoid. Replaced it and drove fine for short time and problem started again and again was told it was EVAP purge solenoid. Why is this happening over and over again. What can I do?
 The purge solenoid would not be causing an engine misfire. It would cause a check engine light yes, but not affect the way the engine runs.

I have a 1994 Buick Century and in the last month or so the engine started making a noise that sounds as if it were literally was a diesel engine. When opening the hood one might there was very little or no oil coming up to top end. Thank You
 It is possible you have low oil pressure, a bad lifter, or more likely one of the rocker arm studs has pulled out of the cylinder head. This would also cause a misfire on that cylinder. Removing valve covers for inspection seems the next step after checking oil pressure.

How do I remove the TPS shaft from the throttle body? It appears stuck from the right side (as viewed from the drivers side). The little piece will not come apart on that side to release the shaft.
 If you are trying to remove the throttle plate shaft from the body, it cannot be done. If you have a problem, the throttle body needs to be replaced as an assembly.

i have a Chevy Impala that keeps saying low coolant level but theres no leak that i can see and we changed the thermostat and reset the computer in the car and it still says that, what could it be? The temperature sensor?
 Cannot be the temperature sensor or thermostat. The light say "LOW COOLANT". If the coolant is low, you have a leak and need to get it inspected closely. If it is not low, then you may have a level sensor problem.

1999 Pontiac Grand Prix need to know where the low coolant sensor is. The light flashed low coolant all the time and it has plenty of coolant and its not running hot at all.
 The low coolant level sensor is in the passenger side of the radiator. Below the radiator cap. It is a square black sensor that snaps into the radiator and held with a clip.

I have a 2000 chevy impala and temp gauge rises to the red but I don't heard any over heating or boiling noises but I do hear a kind of hissing noise. What could it be? The temp sensor I'm guessing.
 If the temp gauge is going into the red, it is overheating whether you hear it or not. You'd have to try and find the exact cause. It could be anything from a water pump, intake gasket, head gaskets or even radiator. I highly doubt you just have a bad temp sensor. Get it checked out soon, or you'll end up losing the engine.

2004 Grand Am gt 3400 v6 and it wont start. The security light isn't on but its not getting any spark and i cant hear the fuel pump. Fuses and the ignition module isn't getting juice along with others. Replaced fuse same result.
 You should re-check all your connections, and make sure all vacuum lines are connected and routed properly. If it idled fine before you did the heads, it has to be something you did in the reassembly process. If it seems like it running rough, you may have switched push rod positions by accident, that will cause the car to die out or run rough. If the check engine light is on, get the code scanned to see what might be causing the trouble.

I have a 2001 Olds Alero, 3.4L. I have been having problems with the Temperature gauge working when it wants to. At time it will work fine, other times it will completely drop out and the electric fans will kick on. It will eventually come back on, on it's own. I've checked the fuses, they where good.. I've replaced the Temp sensor and it's had the same issue. I've ohmmed out the harness and it is good. The wires are not frayed or broken. I have no clue at what else to look at.. Any suggestions??? You think it could be the gauge it's self?
 Probably not a problem in the dash gauges, since the fans come on. The dash does not control the fans, the gauge shows what the computer thinks the temperature is. Either a wiring problem or bad computer.

My 2004 3.4L has a starting issue when the engine is warm. It starts fine when the engine is cold. I can barely step on the gas pedal when it is warm and it will start right up. I have cleaned around the throttle body butterfly and this did no help. Any ideas what may be causing this? I did also see when cleaning the butterfly that there is a opening just past the butterfly about the size of a dime that goes down had some carbon build up coming out of it. I cleaned it out what I could but did not help.
 That opening is the idle air passage for the control valve (IAC). Sounds like you have an idle valve that is not working. You could try to remove it and clean it real good.

2000 Chevy Impala 3.8 and my heat get hot when riding in my neighbor but only blow out warm air when riding on the highway. What can I do to make my heater blow hot air at all time.
 First check the coolant level. If it is OK, you could have one of several problems- A sticking thermostat, plugged heater core, temperature door actuator motor in the dash, etc. Any one could be faulty.

1994 Buick century with a 3.1 recently replaced fuel pump. Won't start yet have 40 psi fuel pressure at the fuel rail. Runs great when starting fluid is sprayed up the intake so I have spark I have no idea whats wrong and it's driving me up the wall.
 Sounds like you are loosing fuel injector pulse. This is controlled by the PCM. Check all fuses, then check with a test light that the injectors are getting a signal to fire.

Chevy Berreta 3.1 running rich can't get the service engine light to go off. I have replaced plugs,fuel filter, regulator egr valve,air filter cleaned port in intake that goes to EGR. Any ideas. Thanks.
 If you are sure it is running rich, the EGR has nothing to do with it. What codes do you have stored. If it is rich and the fuel pressure regulator (FPR) did not fix it, then your car probably has a leaking fuel injector.

1998 Pontiac Grand Prix SE 3.1L engine. The car won't pull a hill in the higher gear, especially when the car is warm. ( pulls it somewhat better when cold ). And even on a flat surface, I just can't take off and throttle as fast I want to. It's a slow acceleration.
 Sounds like a possibly low fuel pressure condition or plugged catalytic converter. Get the computer codes scanned first. May give a direction to the problem.

Problems with a Pontiac Grand Am It is just very difficult to start it sounds like if it is getting to much fuel, because wen I push the gas half way it start. Although it does it with difficulty and for the first seconds the engine sounds like it is going to turn of and it smokes black. Then it starts to function very normal and acceleration is good. Does any body has any idea what can cause this issue?
 Sounds like a leaking fuel pressure regulator causing a rich condition. Just pull the vacuum hose off of it after it has been off for a few minutes and look for gas to come out of it.

I have a 2001 Buick Century press on gas loud whistling no power after half throttle noise goes away can not get overt 30 mph could it be converter.
 The noise you are hearing is the exhaust trying to escape but cannot because your car has a plugged catalytic converter.

2003 Alero 3400. Rough idle, runs fine otherwise. Gas smell in passenger compartment while driving. EGR issue? Fuel injector issue?
 A leaking fuel pressure regulator (FPR) or a stuck open fuel injector causing a rich condition and smell of gas in the car.

Chevy Monte Carlo Z34 when the outside temp is less than 50 the cold car revs 5000rpm then dies. This goes on until the car warms up then it runs fine. It runs fine when the outside temp is over 50. No codes are stored. I have the exact same car and the exact same problem, I have cleaned the throttle body, fuel injectors and MAF Sensor, changed a broken intake manifold gasket, replaced the IAC, PCV, and EGR valves, and it STILL does it. Next thing I'm going to look at, and probably should have looked at sooner is the Intake Air Temperature sensor.
 If you have the 3400 dual overhead cam engine (DOHC) then you have a lower intake leaking vacuum.

Pontiac Aztec 3400 leaks coolant when the motor is warm back behind the back head up by the valve cover behind the alternator there is no coolant in the oil but dont leak when the car is cold and haven't been running cant find or see what would be causing this problem.
 The rear head gasket is leaking. You should probably do both since it most likely has over heated.

Where are the O2 sensors Located on a V6, 3.4L Oldsmobile Alero.
 One is in the rear exhaust manifold, the other is after the catalytic converter.