Question about 1992 Pontiac Firebird
I have had this same simpletons it drove me craze it turned out to be that the catalytic converter had broke a pace off in side and found it's way down in to the muffler causing a restriction in the exhaust .i have also see maf. cause stall outs I give them the good old tap test and if it stall's replace it. if you cant keep it running long enough 4 that test UN plug it it Will run with out it .hope this help you fix your car .i have 5 of them but only one with a V6 like the body]the ease way to test the exhaust is to drop it just be four the cat. best to you .if this has been any help[ a that a boy ] would be nice but not need 4 me . im just here to lorn to spell . Have a Grate day and thank you 4 using fix ya.please let us know if we have helped and what did it so we can keep passing it on .
Posted on Jun 17, 2010
If engine ir running ropugh when idling , the cause is often a faulty idle air control valve, an air sensor, or a vacuum leak.
Check also the fuel tank cap, if this does not let air into the fuel tank, then you may experience problems, particularly when idling. Test the car without cap.
The IAC valve is fixed to the back the throttle body by two torx screws. Disconnect the round shaped connector before removing the screws.
Before replacing the valve ensure that there is no vacuum leaks. Big vacuum leak can be spotted because of the hissing sound coming from the leak. To find small vacuum leak you will need an had tool gauge placed between vacuum lines(eg.Actron Vacuum Gauge).
In some case MAF and AIT sensor faults can also cause idling problem by determining an incorrect amount of air to be used in the mixture. In this case you often get a lean mixture code on the OBDII scanner.
If the failure is related to temperature, then the most likely cause is the IAT sensor (intake air temperature sensor). MAP (mass air pressure) sensor, MAF (mass airflow sensor) and engine gas recirculation system may also concurr in causing the problem.
This sensors are in fact used to determine the quantity of air to be injected along with fuel in the cylinders.
The sensors are located in the air intake.
The first step in diagnosis is doing an error code scanning. This is done connecting an OBDII tool to check if there are error codes stored.
If problem is the IAT or MAF, you usually get lean or rich mixture codes, along with misfire ocurring when the engine is shutting down because the incorrect mixture cause flooding or chocking.
Once you are sure that fuel circulation is fine, the most common cause for rough engine when idle is MAF, MAP, vacuum leaks and IAC valve problems.
Posted on Jun 09, 2010
Ok so let me get this straight, you have fuel pressure(45 psi, good). Are both injectors pulsing? Just because the fuse is good doesn't mean the injectors are. The pass key will only stop ignition and will not have anything to do with driveability. Check the injectors and get back to me.
Posted on May 24, 2010
Hi! GOt MAF (mass air flow) sensor on your car? A faulty MAF has big contribution on engine performance. Might wanna look on that. Hope this helps and have a good one!
Posted on Jun 09, 2010
I suggest you start by replacing the fuel filter if you have not yet. Along with that I would check the fuel pressure regulator. Although this seems like a fuel issue, I recommend replacing the spark plugs and wires. This way you can check the plugs to see if they are fouled and a bad plug wire(s) can cause a very rough idle but as your rpm's increase the engine will smooth out. Also try disconnecting the vacuum line from the EGR valve. I am giving you all of these possibilities because it is very difficult to diagnose from a distance but please comment on this post with questions or more information and I will help you. We can narrow down the possibilities together.
Posted on Jun 03, 2010
Here's some from from my experience. Pull the negative cable for 30 minutes. - Also Try removing the fuel filter completely. If you have moisture of any kind in the fuel your filter is very sensitive to water and can shut down because of moisture. ALSO - while you're at it - take down the VIN # - and call the Dealer asking about RECALLS can save you a lot of money over the years. Also ask about Service Bulletins. SB's are not paid for by the dealer but they can many times give you a heads up concerning problems like this one. RECALLS are good for the life of the car in many cases so please do this and get back to me here on the forum.
Posted on Jun 03, 2010
Thanks for contacting Fix Ya. I have two thoughts given all the work you have done and running good up til now. When was the last time you purchased gas? Wonder about bad gas of water in gas Could put a can of heat in tank regardless just in case. Other thought, did you take fuel pressure check with engine running and watch what happens to pressure when at idle and when you rev the engine? Did you change fuel filters lately? An after thought, wonder if your fuel pressure regulator is working. You may have tried all of this but when it runs good when you are spraying 2+2 we have to know it is starving for fuel. Let me know how you come out with this. Darrell S
Posted on May 25, 2010
How is the fuel filter? Is the throttle body cleaned out? Do you have a service engine light that could indicated dirty or bad sensors?
Posted on Jun 07, 2010
Sounds like u may have a vacuum leak on the engine. follow the vacuum leak diagnosis below.
Vacuum Leak Diagnosis and Repair. [Inquiry]Anyone know of a good method of test for and locating vacuum leaks in the the air intake system?
· By Listening. [Response: Don Foster] Find or buy a 3' length of new fuel hose. Stick one end in your ear and snoop around the intake system with the other end listen for any pronounced hisssssssing. [Warren Bain] I was able to isolate a vacuum leak with a mechanic's stethoscope with the probe removed and only using the tubing to get very close to the gasket and follow the contour of the manifold. You can also modify the stethoscope for locating vacuum leaks by replacing the probe with a length of plastic hose or fuel line.
· Spraying With Liquid. Another trick, for small leaks such as loose intake manifolds or shrunken injector seals, is to spray them with carb cleaner. This will temporarily seal a leak and a rough idle will smooth out for 10-15 seconds: you will hear the change in idle rpm.
· Using Propane to Alter the Mixture. [Tip from Bruce Young] I use Propane to test for vacuum leaks It's as safe (or safer) and less messy than spraying carb cleaner or other flammables . Take the nozzle tip off a propane torch and replace it with some snug fitting rubber hose about 2 feet long. Practice with the valve to get a moderate gas flow (not a roaring blast). With the engine at a warm idle, open the gas valve and poke the end of the hose around each injector for a couple of seconds. If the seals leak, you should hear an RPM change when the propane gets sucked in and burned. Do the same around any other suspected areas, like hidden vacuum hose ends and the intake manifold gasket itself. To block the breeze from the fan, lay a piece of cardboard from the fan shroud to the engine.
· Using Smoke to Locate Vacuum Leaks. Filling the intake system with slightly pressurized smoke from a smoke generator will allow you to see leaks where the smoke emerges.
Posted on Jun 03, 2010
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