Odd AYC

[Reconstructor]

Yesterday decided to drive my Vr4 after several weeks in garage. After driving out of garage, AYC red light of death turned on. :) Then had 2 stops (which mean 2 engine restarts) and the light turned off and never lit again for the entire day. Any explanations? The only thing came to my mind is: 1. Reservoir valve is not tight enough and it cannot hold pressure for several weeks. 2. The pump is sufficiently worn-off to fail of providing enough pressure for the amount of time the ECU is expecting. 3. After 2 restarts, pump finally manages to accumulate enough pressure in the reservoir and system enters in stable, usable state. Correct explanation, or bullsh1t? :)

[Davezj]

I would go with option 3.
the pressure in the pump will leak away over time and the pump seems to prime when you initially turn the car on.
i belive the pump should prime for pressure until it is sensed by the pressure switch the turn off. then reprime when the pressure drops. but these ayc pumps are getting old now and it might take a bit more effort to get it to prime in the first place, but once up to pressure it will maintain pressure happily.

as long as the red light does not come back on you are good to go.

[babasvr4]

Check the AYC power relay next to the battery, open it up and check the contacts, you can re-face them with 600 grit wet n dry.

[Reconstructor]

the pressure in the pump will leak away over time.

So, is the leaking something normal, or wearing is the cause?

[hardarse]

i have the same problem. i didnt use my car for a while and when i did finally get it out the unit the pump takes ages to stop then the red ayc light comes on. but the weird thing for me is the first time i drive the car in the day the ayc light doesnt come on. but when i use the car again after the first run. the ayc light always comes on. so im thinking would getting a new switch help.

[Davezj]

So, is the leaking something normal, or wearing is the cause?

the AYC fluid resovoir in the boot is not pressurised it is just a resovoir for fluid.

when i say the pressure is leaking away, It is not technically leaking it is just loosing pressure in the pump as you would expect over time. the pump will not hold pressure for ever. when you start the car you should be able to hear the AYC pump run then shut off after it has reached the required pressure. if you jump in the car start it and go you might not have enough pressure in the system by then and it registers a low pressure reading and RED AYC comes on. but if you switch the ignition to ON i think the AYC pump primes at this point. so you could try and leave the ignition on for a minute before staring thte car and see if it make a difference.

but as i said above the pumps are getting old now and corrosion has probably set in and it is this that is causeing the pump to fail. but a variable pressure switch is a temp fix for low pressure.

[Nick Mann]

My pump doesn't start up until the car moves. If I get in and turn the ignition on, nothing. Start the car, nothing. Drive the car a metre or so and the pump jumps into life.

[Davezj]

Thanks for you info nick, glad you jumped in, i should have known that.
sorry my info was duff, i think it was because we had a car up in the air on saturday and the pump was running but that would have been because we had the car in gear. Muppet, LOL.

[hardarse]

dont know if it is anything to do with the problem. but i adjusted the screw on the throttle body on my legnum to around 700 rpm since it has been running at around 600 rpm when on idle. then i disconnected the battery for a minute. and since then the ayc pump has been working well and the light stays off.

[Nick Mann]

Slightly more voltage to the pump at 700 rpm? Not sure I can think of any other reasons why a few extra rpm helps the AYC. Even then, as the pump doesn't start until you are driving, the idle rpm should make almost no difference.
I can't explain it, Keith, but if it worked then nice one! :D

[Reconstructor]

On my opinion, pump starts only upon signal detection from pressure switch. So, if you have enough pressure in the reservoir, it won't start, even if engine is cold and just started. Which is normal operation logic, since otherwise, the pump will deteriorate very quickly.

[Reconstructor]

I'm talking about pressure reservoir - the big metal sphere at the one end of the pump assembly. It have a one-way valve, which let the pressure in and don't let it out. However, if it leaks, the pressure will drop over time.

[Nick Mann]

On my opinion, pump starts only upon signal detection from pressure switch. So, if you have enough pressure in the reservoir, it won't start, even if engine is cold and just started. Which is normal operation logic, since otherwise, the pump will deteriorate very quickly.

That must also be true. However, in my experience if the car is left overnight the pressure drops enough that the pump needs to operate to bring it back up. However, it doesn't do this until the car starts moving. This has been true on all of my VR4s.

[Reconstructor]

Well, My AYC needs week or more for pressure to drop. :) So, leaking must be normal then.

[hardarse]

ive had a couple of vr4s now and even after a very short time of been switched off then on it will always drop pressure. but the ayc has stayed off since the play about. so it could be worth trying for anyone else who has this problem.