many different factors can result in a bad idle on a vehicle. some of them is the fuel pressure regulator, the throttle positioning sensor (located on the throttlebody) and faulty plugs & wires, or fuel injectors
yes a fluctuation in pressure could cause it. check pressure with a guage
If you Google "Symptoms of a faulty fuel regulator" you will get quite a few hits. If the regulator is bad it may cause either a drop in fuel pressure or an increase in fuel pressure at the rail . A drop in fuel pressure, if severe enough, can cause bad or no idle condition, engine starving for fuel and etc. If the regulator is causing excessive pressure it can cause fouled plugs, black smoke from exhaust and rough engine performance. Before you change the regulator check for cracked, rotted or disconnected vacuum hose. Also you can connect a fuel pressure gauge to the schrader valve on the rail and monitor the pressure to see if it is in specifications, or to see if the fuel pressure drops rapidly after engine shutdown. Hope this helps and good luck with your problem. Dan
you push on the gas and it wont go or runs rough or dies when accelerating /// a pluged fuel filter will also cause thes symptoms as well
Most likely cause could be the fuel pressure regulator located on injector rail with vacuum hose attached to it. This vacuum hose when disconnected after the engine has been shut off 15 minutes should show signs of fuel indicating a bad regulator.
To diagnose a bad fuel pressure regulator on a 2000 GMC Safari van, start by checking the fuel pressure with a gauge to ensure it matches the manufacturer's specifications. If the pressure is too low, it may indicate a faulty regulator. Additionally, inspect for fuel leaks around the regulator, and observe if the engine runs poorly or exhibits symptoms like rough idling or stalling, which can also signal a malfunctioning regulator. Lastly, a vacuum line connected to the regulator should be checked for fuel presence, as any fuel in the line indicates a failure.
Some possibilities include: faulty or dirty MAF sensor, fuel pressure regulator, or the torque converer solenoid.
I would suspect the fuel pressure regulator valve which is located between the fuel rails beneath the plenum. If the diaphragm inside the valve fails it can allow gasoline to enter the vacuum line that operates the valve and then the gasoline can be pulled into the throttle body then migrate down to the air filter. If the pressure regulator is defective it can also cause rough idle and stalling at idle. You can do a check for this situation by removing the multiple port vacuum line fitting that plugs into the top of the throttle body. If gasoline is present in the plastic line that usually indicates a faulty fuel pressure regulator valve.
bad coil(cop hates heat, coils short out when hot) bad gas-vapor lock bad fuel pressure regulator bad drainback valve, no fuel in the rail
Unlikely, Fuel and/or spark are likely culprits.
Seem to be good, my rough collie is a legend
It is ECM controlled But a rough idle is probably a bad fuel pressure regulator of clogged fuel filter. If the exaust smells rich its the regulator. Will also turn on P0172 and P0175 OBDII codes. Fuel system Rich on both banks.
It's extremely unlikely. Much more likely is rough running (usually due to engine management fault) causing a lack of oil pressure. Also, keep in mind that an excessively worn engine can cause both low or erratic oil pressure and rough running, but this will usually be accompanied by a knocking noise.