Fluctuating Revs

[Myster X]

I've just barely gotten the car home after it cut out. A few weeks back it started shaking then the motor intermittantly cuts in and out, then the battery light comes on and I think the power steering cut out cos it got really heavy. I left it and came back a while later and it started up fine and had no probs for weeks.

Then today the same thing, it starts shaking, the revs just drop to zero, then they come back, then they drop. It mainly happens when im idle at the lights.

I just got the starter motor replaced so it can't be that. Given that the steering stuffs up I'm hoping its an electrical fault. Help please

[bangers]

the steering will stuff up as soon as the engine stops ticking over and turning the pump. maybe your coil is stuffed?! It seems to me that its either that or maybe a bad earth somewhere. It could *possibly* be fuel. the battery light will be on cos your reds are on but the engine isn't. Start at the cheapest possible scenario and work your way up.

[ucwepn]

It sounds like a fuel supply problem possibly the fuel pressure regulator or failing that it will be electrical, These nissan motors are very reliable units but finding the faults can be a headache sometimes. Listen for the noise your fuel pump makes when you turn the key 1 click (like a buzzing noise) this noise means the fuel pump is ok, you should even be able to hear it at the lights when you've stopped and its quiet.

[My Car Pwns]

yep mine did that last week.. it was jus the heat had dried up some fuel n turned it to air.. (theres a word for that but i cant think straight atm.. )
the car shakes n chokes a bit then turns off.. then it starts again normally.. jus open your petrol cap n that lets the air out.. if its a constant problem then u mite have corroded or cracked or blocked fuel lines..

[bencom]

Check air flow meter
had the same prob

[Myster X]

Well I took it to a mechanic a few weeks back, he changed an old plug on the distributor that was falling apart which he said could definitely be the problem (he wasn't sure).

Its driven fine ever since but I've been paranoid the same problem would come back. It doesnt shake at the lights massively like it has but it does have a minor throbbing that i dont remember it having before.

2 days ago the same problem. slowed down to take a corner and on accelerating it screams off then cuts out then revs back up again. Got it home and it cut itself out before i got it in the garage and it wouldn't start again for a while.

It sounds like a fuel supply problem possibly the fuel pressure regulator or failing that it will be electrical, Listen for the noise your fuel pump makes when you turn the key 1 click (like a buzzing noise) this noise means the fuel pump is ok, you should even be able to hear it at the lights when you've stopped and its quiet.

Yeah i did notice this sound predominantly when i had a starter motor issue a while back. I can go out now and start the car but im not really sure im hearing the same buzzing as I used too or any buzzing at all.

If it is a fuel supply problem (which in my limited knowledge sounds right given how the car feels when it stuffs up) where can I take it to get it fixed. Im not a diy-type i just want to know what kinda place will fix it as cheap as possible.

Are we talking Ultratune or like a standard mechanic?

Thanks for any tips you guys can give me.

[vlv8vic]

i doubt itll have anything to do with the starter motor... it wont have changed the noise your fuel pump makes, maybe only by disguise.

[Myster X]

i doubt itll have anything to do with the starter motor... it wont have changed the noise your fuel pump makes, maybe only by disguise.

No, I realise that. What I mean was when it wasn't starting all, what I heard when I turned the key was that buzzing and thats what made me notice it for the first time rather than any other time when I would just expect the engine to turn over and the car to start. Im confident my current problem has zero to do with the starter motor.

[Stewart1000]

yeah... why would it have something to do with it if it stuffs up at the lights while idling. take the fuel line off the engine and see if petrol comes out at a fast rate or just slowly drips out, if it comes out under pressure it prob isnt the fuel system but could still be, i dont know much bout the fuel system.

[Myster X]

Ok the cars been out of commission for a while now, i've been using alternative means of transport, but now i want it fixed.

I went out and tried to start it up before and once I got past the inevitable problems of starting a car up thats been sitting there for a few weeks I got it running. As expected while just sitting there it had this shaking that it hasn't had before and upon revving it just kinda splutters like vroom....vroom....vroom not one constant vroom as it would normally.

The general consensus from what i've read is the air flow meter. What do the symptoms tend to be when it stuffs up? Oh and does anyone have a ballpark figure of what it will cost to fix?

[hertygerty]

If you unplug the AFM of the car it should start and run but not rev over 1800 rpm {it is in limp mode} This will Prove the AFM is working .If it is faulty you can get rebuild ones at BURSONS last one cost $186

[nicholasjoe]

i had the same problem on my 4 cyl 18R motor, turns out that the auxilliry fuel pump diaphram had shit itself which resulted in no secondary fuel supply, especially in cases when i put my foot down. but overall affected the idle and made the motor cut out whilst and only when the engine was running warm. i also replaced my electric fuel pump as it made a fluctuating sound like your idle after some time of driving. This may slightly be off topic in terms of a nissan motor. but maybe food for thought?

[Stewart1000]

if it revs cuts out then revs cuts out and then revs... are you revving it very hard? because if you are you might be hitting the limiter

[Myster X]

Nah i don't rev it much at all, it happens like when i go to pull off from the lights or when I take a slow corner, it also happened when I tested it out in the garage just easing the accelerator down

[nicholasjoe]

check your engine vacuums for leaks. Get some carby cleaner or something and spray all around the vacuum hoses and joints. And see wether or not the motor revs up.

[thestash_16]

i had the same problems, on my old car (a ford) and i adjusted the idle speed and it stopped dropping out.