I've been told that turning your ignition key to the ON(II) position for a few second before starting allows the electronic fuel and oil pumps to prime. You can see this as fuel gauge starts to register after a few seconds. Is there any advantages to this with the oil system allowing it to pre-lube faster when starting?
Advantages to turning ignition on before starting?
- Thread starter Mobil2
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Oil pumps are not electric - it has absolutely not effect on the oil system. You're really not doing anything good for the fuel pump either, it might start slightly quicker, but you have to wait for it to prime. I allways let my Jeep prime before I crashed it, but that was because the fuel pump was going out and it had to crank for 10+ seconds before it would start...
Maybe some systems, but I don't think it matters.
BTW I usually do let it set on several times mainly in the morning a few seconds before I start. I may be wrong, but I believe in letting my pump take it's time first off... I like to hear the pump and when it starts to go out, it usually will stall before comming up and I HOPE that I can catch it before it does go out... so when I start it & hear it DELAY, or not
then delay, or work right after a bad start,
I know it's going. They will just die sometimes but usually In My experiences, you can hear them sometimes for months or longer before they will not come on again... This way I try to prepare myself for the worst... That's whay I do it!
BTW I usually do let it set on several times mainly in the morning a few seconds before I start. I may be wrong, but I believe in letting my pump take it's time first off... I like to hear the pump and when it starts to go out, it usually will stall before comming up and I HOPE that I can catch it before it does go out... so when I start it & hear it DELAY, or not
then delay, or work right after a bad start,
I know it's going. They will just die sometimes but usually In My experiences, you can hear them sometimes for months or longer before they will not come on again... This way I try to prepare myself for the worst... That's whay I do it!
i dont know what you guys are doing but on most cars the fuel pump wont turn on unless the engine is revolving.
a safety feature.
on some cars, it will do a short 1-2 second prime if the key is turned to the ignition position, but the pump should quickly turn off after its preset time (1-2 seconds give or take if your car does this)
having a fuel pump continously operating while the ignition is on, but the engine isnt running would be dangerous. so letting the car sit with ignition on for 10 whole seconds shouldnt do anything more than letting it sit for 2 seconds.
a safety feature.
on some cars, it will do a short 1-2 second prime if the key is turned to the ignition position, but the pump should quickly turn off after its preset time (1-2 seconds give or take if your car does this)
having a fuel pump continously operating while the ignition is on, but the engine isnt running would be dangerous. so letting the car sit with ignition on for 10 whole seconds shouldnt do anything more than letting it sit for 2 seconds.
Most domestic vehicles start ALOT better if you turn on the ignition and wait a couple of seconds till the PCM gets all the readings from the various sensors..then crank the engine...I turn on the ignition and watch the dash till a few of the "idiot" lights go out (couple of seconds)then crank...nine outa 10 times vehicles start faster...IMO.
I've gotten in the habit of pausing the key in the run position before I crank it. The argument that I read was that it allows the various microprocessors to get their act together. Sort of like Greaser's comment. Makes sense.
If the ECU/PCM is taking more than a second to get it's act together...bad design IMHO. Remember, the engine starts up in open-loop mode.
I know on my car, the fuel pump does not turn on until the igntion is on and the engine is turning, but on all GM vehicles I've owned, the pump turns on for about 2 seconds when the key is turned to on.
And one other thing to keep in mind, is when the key is in the off position, the ECU/PCM is still powered up, it just sitting in a prolonged wait state. If it makes you feel better to sit more than a second with the key in the on position, by all means, have at it, it won't hurt anything.
On Fords since 1992 the FP will run for 1 sec when the key is turned on. If your pump is worn this will help to build pressure to maybe cycle the key a couple of times. Also on Fords built since 1992 with FI if you crank the car with the gas pedal floored the FIs are turned off so the engine just cranks. This is kind of like priming the oil system.
Aren't newer O2 sensors 3 wire (pre-heated) type and work better when they get older when you hold off cranking a couple of seconds before starting?My 01 and 99 Jeeps both have the fuel pump working before I fire them up...I can here them...and know that Jeep vehicles start with less cranks if you wait a couple of seconds before starting..just my observations
Yes, turn on the ign sw and you can hear it run for a few seconds and cut off. Then turn the sw to the 'start' position. If your Elec. fuel pump is weak, try turning it on and off a few cycles. BTW the dash fuel gauge does not indicate pressure at the manifold, but quantity of gas in the tank.
You are right. I dont have your skill in verbage... I like the way you say it (correctly).
Engines start in open-loop mode, O2 sensors don't come into play.
Building fuel pressure and waiting for the ECU/PCM to get it's act together is two different things.quote:
My 01 and 99 Jeeps both have the fuel pump working before I fire them up...I can here them...and know that Jeep vehicles start with less cranks if you wait a couple of seconds before starting..just my observations
A better description would be that the fuel pump turns on to insure the fuel rails and injectors are within operating pressure parameters before you start the engine. This is a good thing! I believe all FI cars do this. The point I was trying to make was that the faster starts experienced were do to this, not due to the ECU/PCM getting it act together. Hope this helps.
This is interesting! So if you stood outside your Jetta and open and close the door repeatedly, the fuel pump turns on for a couple of seconds everytime?
Short on/off cycles will kill anything. Do you want to give your fuel pump and maybe other components an extra one each time you start the engine? Also, I would just as soon give the oil pump a few extra revolutions before the engine starts. This sound to me like one more way to mess around and cause more problems than you prevent.
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