Hello everyone

My 1999 V-reg Fiesta has been suffering from the dreaded idling & running problems and I've been following the usual advice.

It sometimes tries stalling when approaching junctions, it seems the engine is trying to kep the revs up and is sometimes kangarooing when trying to change down through the gears to second while slowly coming to a halt.

I noticed yesterday that it was idling at 1100 revs when stopped at a junction even though the engine was fully warmed up after 30 mins of driving on motorway and fast a-roads.

I cleaned the idle-speed control valve (ISCV) with carb cleaner and also tried a new one,

I checked the power steering pressure sensor and wiring for corrosion and it ppears fine,

Removed the MAP sensor from the intake manifold and sprayed with electrical cleaner,

Removed the throttle position sensor and inspected visually.

The sparkplugs and leads were replaced 8 months ago (NGK plugs, Magnecor leads), I checked the plugs the other day and they were all fine (golden brown).

The coil is the original, seems to be OK visually, can't see any arcing, I took it off to get at the coolant temp sensor and looked underneath at the sealant and it looks fine.

I friend of mine is a mechanic at an MOT testing station and checked the readings with the emissions probe.

The CO2 levels were slightly high (I think 15.7 with 16 being max permitted) but it was registering 0 on CO at idle and only 0.03 at 2500 revs which is much lower than expected. He thought it might running lean and suggested I check the coolant temp sensor to see if it was covered in sludge or faulty.

I removed the coolant temp sensor from below the ignition coil, and it looked clean with no apparent sludge on the probe. I dipped the tip in a sink of hot water and measured the resistance with a multimeter. The value changed quickly when dipped in the hot water, but I didn't record the values. I think it was about 40 Ohms and then fell to about 20 when dipped in the water. I thought it seemed to be OK so I re-installed it and refilled the cooling system with fresh OAT antifreeze 50:50 mix.

I ran a console diagnostics check today by holding down the trip/reset button and turning the ignition to position II.

I got the DTC fault codes of 9318 and 0115.

I googled the codes and it seems 9318 = battery voltage low and 0115 = engine coolant temperature malfunction.

I checked the battery voltage the other day with a multimeter and it read 12.8v.

Today I used a Gunson battery/alternator tester and it reported the battery and alternator were fine including with the lights on main-beam, fan on max, rear screen heater on. Multimerter reading was 13.4v.

The battery was replaced by the RAC about 4 years ago when the old one failed, I peeled off the RAC label and its branded as an Exide Expander, is this a Silver Calcium battery, is one required?

With regard to the coolant temp malfunction DTC, should I remove the coolant temp sensor again and test it? What resistance values should I be getting from it at what temperatures?

Sorry for the very long post, I tried to give all the info I can think of.

Thanks in advance.

Paul.