Idle speed

sassy_one

Hi


I recently took my car into a garage for a look at why the car has recently failed to start, turned over slow and also broke down on the motorway and lost all power, both engine and electrical.

After an hour the garage called me and advised me to come in again, which concerned me a little as why they did not tell me over the phone the problem.


I have been told my battery is fine and they have carried out a 'Drop Load' test which showed flying results.

However, after other tests carried out I am told my Idle speed is low, at just 450-500 RPM and I have a 'lazy' but not failing completely, yet, Alternator.

Firstly, the garage told me they have manually adjusted the idle speed by jamming tick over speed at 1000 RPM now but this MOD can be removed when a permanent fix is carried out, however the garage did advised me that the ECU will self adjust after a certain time and will drop it's revs back to 450-500 RPM which seems normal to the ECU to operate/run at.

What they explained was after doing the tests on the car's charging system they have found that the car idling at 450-500 RPM without any electrics on is fine, and the car could run all day at that and charge the battery fine, but when you put head lights on or the Air-Con, in traffic or at idle I am taking more power out than is being replaced causing the battery to go flat and stall the engine.


Regards the alternator I have been told if I get the RPM up to 750-ish that this may cure the problem but worst case I need to replace the alternator too.


How can I adjust the RPM?

The car is a Ford Mondeo 2.5 V6 on a 2000 plate, and is automatic.


I understand there are settings on the on broad computer but can I alter the Revs per minute in there or not?

All advice welcome

Thank you in advance!

Rolandtheroadie

http://www.btinternet.com/~madmole/Reference/Idle.html

Have a look at that.
Forget the 450-500, and the "get it to 750 and it should be ok" stuff, find out what it SHOULD be before you go any further.
Also forget about ecu's learning and adjusting and everything else. The only solution is to fix the fault which is the wrong tickover/idle rate.

sassy_one

scotsman4th wrote: »

http://www.btinternet.com/~madmole/Reference/Idle.html

Have a look at that.
Forget the 450-500, and the "get it to 750 and it should be ok" stuff, find out what it SHOULD be before you go any further.
Also forget about ecu's learning and adjusting and everything else. The only solution is to fix the fault which is the wrong tickover/idle rate.

Thanks for the post and the link, have been having a read and will look into some of these things ASAP.

skiddlydiddly

That site linked above looks pretty comprehensive and mentions plugs and leads.Didn't you say in another thread you'd changed them fairly recently?

thescouselander

Engines with more cylinders can sometimes idle slower than a normal 4 pot engine - I wouldn't be surprised if 500 rpm is the normal idle speed for that engine. Its probably best to confirm the correct idle speed before messing about with anything.

skiddlydiddly

I have an adjustable fuel pressure regulator and know when I drop the pressure too low, the idle falls to the point of stalling, similarly if I increase it too much it revs way too high.Makes me think it could also possibly be a failing fuel pump.

sassy_one

HT Leads and Plugs were changed but the leads are from eBay so can't be 100% sure of there quality.


Fuel isn't too bad recently, since the temporary MOD on the RPM the car has be running fine

Pew_Pew_Pew_Lasers!

If the alternator is failing, then why not just have it repaired, or replaced?

Being stuck in the dark on a freezing cold evening is no fun.