Please take pity on a UK Fairmont owner (maybe the only one). Virtually no-one in England has even heard of a Fairmont - so info is REALLY hard to find. Any help will be much appreciated.
My 1997 Fairmont 4 litre (petrol and LPG) will only idle at about 1700-1800 rpm. From a cold start it goes to about 2400 rpm and, as it warms-up, drops to about 1700.
This is on petrol, switching it to LPG invites backfires in the airbox. I have changed the water temp sensor (in the cylinder head), the inlet temp sensor (in the inlet manifold), the Manifold Actual Pressure (MAP) sensor (black box on bulkhead) and the Idle Control Valve. None have made the slightest difference. My local 'expert' has been unable to read the ECU for faults as his equipment is not compatible with my car.
There seems to be no mechanical problem (have checked throttle-stop, cruise control return, etc).
It does seem to be running a little rich (is this a clue?)
Any suggestions will be most welcome as I cannot tolerate my friends sneering at my pride and joy.
Thank you for the reply. I had already found all this info and printed it out for my technical man but he said he was unable to get the test light to blink although the car did go through a sequence of activating the fans, etc.
He seems to think my car is an EEC V (although all the info I have found suggests it is EEC IV).
start with one thing at a time
The EF used the 100 pin EECV
LPG first... try and stop the backfiring issue
Have you done the plugs and leads recently?
Are you using the correct heat range spark plugs, did you reduce the plug gap alittle?
Check the balance line from the convertor to the airbox.. It a large silver duct about 30 mm in diameter.. If that is kinked, creased or damaged the car will back fire or stall <--- that is assuming you have the Tickford factory setup
Check all along the intake plumbing for cracks caused by the LPG blow off.. squeeze the concertina joiners to make sure that are in A1 condition
Once you have eliminated the backfiring it might just be a case of reseting the base idle..or a binding, sticky acelerator cable or linkage
As you have replaced the ICS did you reset the idle?
You can always wind the throttle stop in on the throttle body if the car is not surging to reduce the idle
Once you have the LPg sorted we can look further at the idle issues, but chances are it is not anything to do with the ECU
I thought my Fairmont was an EL - but I may well be wrong. It does have the original LPG set-up.
Some of your suggestions I can eliminate quite quickly:
HT leads were checked and plugs replaced about 8000 klms back.
The concertina pipe was damaged by the last backfire and has been replaced.
Throttle cable, linkage and butterfly checked and all OK.
Balance line - did not know about this - is it beneath the airbox (not sure what I am looking for here).
The Idle Control Valve is used on several UK fords and readily available. I borrowed one and tried it with no success and have now reverted to my original again. The idle was not touched at that time.
The engine is not surging - just idling too high.
The last backfire and the high idle speed occurred together on a cold start-up (but I don't know which caused which). I am reluctant to switch it back to LPG at its current high idle speed in case this causes another backfire.
I will look for the balance line and check it tomorrow and will post here again.
Thanks again for your help - it is greatly appreciated.
sorry my bad, 97 is EL ... I'd be looking at winding down the idle on the throttle body and going from there.. The cold start thing could be the convertor freezing up.. If you can get it running at all on LPG carefully touch the gas convertor to make sure it is getting nice and hot...
The balance line runs from the convertor across the front of the car, above the thermos and into the airbox
The car will run OK on the road on petrol or LPG (thank you Tibbo).
On petrol it idles at 2000 rpm.
On LPG it idles at 700 rpm but this often dips to about 3-400 rpm.
The ECU is showing no faults when I do a Key On Engine Off test (thank you AUGhiaV8)
Disconnecting the plug on the idle control valve makes no noticeable difference.
If I pull the pipes off the idle control valve pipes and put my finger over small inlet hole the idle drops to about 1600 rpm.
I suspect an air leak (with the ECU compensating by increasing the petrol at the injectors) and hence the high idle speed. Of course, on LPG this would have no effect as the injectors are not operating. DOES THIS SOUND FEASIBLE as I am guessing here?
I have searched everywhere for an air/vacuum leak (including the servo) and cannot find one (thank you CSV_LS1).
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