Ecu

[wanneroo]

For many many months I have had problems with the EF fairmont not wanting to start after having been warmed up then standing for around 3hrs I had to press the throttle down to get her to start, I had the vehicle in to auto electricians three times and other mechanics they found no problems so they changed the injectors which I supplied plus an ignition bank a TPS module and mapping module plus an oxygen sensor complete set of ignition leads and plugs a new temperature sensor the ECU was also re coded
this cost me a fair bit of money, The fault had not shown up it was intermittent however it presented the same problem no one could find the issue it cleared
This week I got in my car and stated her she cut out each time I started her no idle at all I called the RAC they came and suspected a vacuum leak to no avail The car was put on the truck and taken to the RAC repair dept it was then taken to an auto electrical place where they diagnosed a faulty ECU I was quoted $600 to have this changed and all set up
I went today to collect the car paid the repairs I was very surprised she started like very quick and drove with a very responsive touch on the throttle she flew like never before she idled in Drive at 700rpm rock steady I am very impressed that the ECU could improve performance like this I am beginning to wonder if the ECU had been the problem all along with starting I don't all I know its like driving a new car I know my car well having had her many years but wow what a change to her running

[Dr Terry]

I'm surprised that you couldn't find an auto electrician more familiar with common Ford ECU problems.

I've been in the auto industry for 40+ years & these days do a lot of work in the EFI area.

Most cars' ECUs are very reliable, but every now & then we see regular failures on one particular model. Arguably the common failure with Ford ECUs (of all series) is the idle circuit in EF 6-cyls. This was definitely your problem all along.

With the idle circuit not working, you will get intermittent hard cold start, occasional stalling, worse in high load situations, i.e. A/C on, in drive, headlights on etc, etc. At one time, a few years ago we used to sell several of those units each week.

Dr Terry

[snap0964]

The EF idle driver is a common fail. Without the idle speed controller receiving signal from the ECU, they'll be no RPM pickup for all the various loads - normally with the car running, if you disconnect the plug from the ISC, the car should stall.

[wanneroo]

Thanks gentlemen for your comments tell me is it normal to idle higher at a cold start I took her out of my parking area parked up outside I noticed the RPM was running around 900 is this normal for a cold start I haven't been out in her yet just picked up your replies she was at 800rpm prior to the new ECU

[Dr Terry]

Originally Posted by snap0964

The EF idle driver is a common fail. Without the idle speed controller receiving signal from the ECU, they'll be no RPM pickup for all the various loads - normally with the car running, if you disconnect the plug from the ISC, the car should stall.

Not quite, I've found that if you unplug the ISC, the revs should drop from 700 to around 600 at a warm idle in neutral & no A/C etc. If it stalls, then the throttle body needs a good clean or the base idle stop has been set too low.

Dr Terry

[snap0964]

Well, that's what I've found typically, and the cars are warm idling around 700 RPM with ISC disconnected and the feeler gauge in place, the few I've tested.

Originally Posted by wanneroo

Thanks gentlemen for your comments tell me is it normal to idle higher at a cold start I took her out of my parking area parked up outside I noticed the RPM was running around 900 is this normal for a cold start I haven't been out in her yet just picked up your replies she was at 800rpm prior to the new ECU

It's not unusual, the cold start/run tune of these cars is set quite rich - what's the idle when at normal op temp ?

[wanneroo]

My fairmont is still at around 900rpm on idle when warm and out of gear, I called the RAC who replaced the ECU they said to run it a few days for the new ECU to learn sounds a little weird maybe its correct ?

[Dr Terry]

Originally Posted by wanneroo

My fairmont is still at around 900rpm on idle when warm and out of gear, I called the RAC who replaced the ECU they said to run it a few days for the new ECU to learn sounds a little weird maybe its correct ?

Sounds like a little bit of BS. It only takes a few minutes for an ECU to '"learn" the idle routine.

Firstly I would verify, with another tacho, that it is indeed idling at 900. Don't trust tacho in the dash.

An engine can idle too fast for 1 of 4 reasons:-

1. ECU or associated sensors faulty.
2. Idle motor not sealing at rest.
3. Base idle screw set too high.
4. Inlet manifold (or similar) air leak.

1. This is easy to eliminate, just unplug the idle motor at warm idle to see if (& by how much) the idle speed drops. If the idle drops, check the electronics. If it doesn't drop move to no. 2.

2. To eliminate a faulty idle motor, remove it & temporarily block off the 2 holes, where it's mounted. If the idle drops, replace the idle motor, if not go to no. 3. Also you can check the idle motor off the car, by just trying to blow thru it, it should NOT pass thru any air off the car. If it does, it is faulty. This applies only to this style of idle motor. Stepper motor types, as used by various other manufacturers are not diagnosed this way.

3. Check to see if the base idle screw has been tampered with. If it has, try to unscrew it to check its affect. If in doubt, remove throttle body & check to see that it is almost fully closed when the throttle is at its stop. Quite often they need nothing more than a good clean & base idle reset.

4. Once you've made sure all the above 3 are OK, check for manifold leaks. Sometimes this might be a leaky brake booster or other device not actually at the manifold itself, so check all hoses. Maybe use a carby cleaner spray to spray around the inaccessible gaskets (with the motor running) & see if the idle alters, it might even increase. If this happens try & localise & then repair the leak.

All of the above assumes than the car is factory stock & is in a good state of tune & that the thermostat is operating to full temperature. If the engine does not reach full temperature, the ECU will hold the idle up slightly until it does.

Dr Terry

[snap0964]

Yeah, idle is too high, if there aren't any faults as covered above, I'd say they've not set idle correctly.
If you don't have a tacho handy, compare the digital reading to the analogue tacho, use http://www.fordmods.com/ford-technic...iagnostics-d12 .
Just remember the cluster will revert to normal mode when the car is switched off.

[wanneroo]

Many thanks guys for your input and all the information, I will see how she goes in a weeks time. I don't use her too often, however if it persists I will drop it back in to the RACWA I suspect the idle setting is set too high Cheers