Tickover To Fast

[DaveH]

Hi i have already asked this question but not sure if i did it right,

My 1989 cabby is ticking over to fast i have been told it could be the auxiliary air valve, can this be taken off and cleaned and if so with what?. Or is there a way of testing it before taking it off.

Thanks.

[Paul Grainger]

Hi Dave, they can be cleaned with brake cleaner. Avoid anything oil based as all sorts of dirt will stick to it.

To test is on the car just disconnect the throttle sensor, the idle should drop to 750 rpm. Don't worry if it cuts out, just adjust the air bleed screw on the throttle body until it will idle.

If the idle speed does change or the engine cuts out then at least you know the valve is working.

If it is working, and you have adjusted the air bleed screw, and you still have problems then disconnect the speed sensor. These can cause high idle speed when faulty too.

Good luck.

[DaveH]

Thanks i will try it tomorrow.

[DaveH]

Hi Dave, they can be cleaned with brake cleaner. Avoid anything oil based as all sorts of dirt will stick to it.

To test is on the car just disconnect the throttle sensor, the idle should drop to 750 rpm. Don't worry if it cuts out, just adjust the air bleed screw on the throttle body until it will idle.

If the idle speed does change or the engine cuts out then at least you know the valve is working.

If it is working, and you have adjusted the air bleed screw, and you still have problems then disconnect the speed sensor. These can cause high idle speed when faulty too.

Good luck.

Thanks i will try that tomorrow.

[DaveH]

Hi Paul

I am new to Escorts but have worked on lots of older cars (i'm not a mechanic) but generally know my way around an engine but not where wiring is concerned.

where do i find the throttle sensor wire and the speed sensor wire and what color should they be . sorry to be a pain but the car runs fine but it is ticking ovr at 1200 revs and its getting on my nerves.

Cheers Dave

[Paul Grainger]

Hi Dave. The throttle sensor is on the end of the throttle butterfly on the opposite end to the linkage where the cable goes on. It is supplied with 5v from the ecu and a ground. The third wire is the reference voltage back to the ecu. Should be about 0.5v at idle going up to 4.5v at full throttle.

 

The speed sensor is located on the gearbox where the cable screws on. This is a hall type sensor and produces a square wave form when moving. The faster you go the higher the frequency. The idle should hang up until you actually stop but the sensors fail internally and you get interference going up the signal wire to the ecu. This will keep the idle speed high as the ecu thinks the car is still moving when it isn't.

The cable unscrews from the sensor and the sensor unscrews from the gearbox.

If you follow the wiring up from the sensor you will find the three pin multiplug on the baulkhead near the brake servo. Disconnect it. If your tick over speed drops then the sensor is faulty.

Some people leave them disconnected but then you can get problems with cutting out.

Good luck.

Edited April 8, 2017 by Paul Grainger

[DaveH]

Thanks again

will have a look tomorrow