I thought I might throw a few images of some of the changes I have made to my JTS engine bay to counteract a few common problems.
To start with here is an image of the whole engine bay to help make the close up images make sense.
One common problem that results in missing, drops in throttle and very annoying misbehaviour are the pre cat oxygen sensor connectors. After getting sick and tired of fiddling with them I took the drastic measure of soldering them; yes I know the bosch data sheet tells you not too but soldering them solved the problem for me with no side effects. I suppose if you do it, try not to get the wires to hot and all should be fine. See the image below for the soldered connector that resides by the air conditioning compressor.
I used to experience a loss in clutch pressure after long trips especially in hot weather. The big silver sheet of aluminium in the image below is my answer, I intended it to act as a clutch master cylinder heat shield and after installing it I have had less frequent losses in pressure. I did however have to recondition the master cylinder first as it was leaking.
The image above also shows how I removed the big electrical block connectors on the back of the engine. Step one was to place them on the firewall instead of on the intake manifold, step two was to get rid of the upper wiring loom’s connector (brown) by soldering all the wires, step three was to replace the lower engine wiring loom’s connector (black) with multiple block bullet connectors
Do not just solder the lower engine wiring loom (black) as the next person who drops the engine will not be very pleased with you which will add to the cost of whatever is being done.
To be extra fastidious I have replaced the batteries ground connector
as shown in the image below.
This may help some of you trying to get rid of misfires and random drops in power. Some of it may be over the top but all of this costs very little if you do it yourself. Be warned if you do rewire the engine wiring looms it takes quite a long time and results in a sore back.
I also recommend replacing the standard Alfa pipe clips with screw type pipe clips on the PCV pipes (ones leading to the main intake pipe) to remove the possibility of vacuum leaks from those areas.
From recent experience it is worth checking out those red relays in front of the battery. If they click then the signal circuit to the relay is all good but if say the fan won't come on, the air con clicks on and off randomly or the car cranks but won't start maybe try swapping the relays around and see if the problem follows it. 12V 30amp spst relays can be easily sourced at local electronics stores for next to nothing so there is no point going to a dealer for them.
Here are a few more bits of advice I can pass on due to unfortunate experiences...
For idle problems maybe try:
1) A throttle reset
2) Cleaning the throttle body
3) Checking for intake leaks after the MAF
4) Replacing the PCV valve
For subtle misfires maybe try:
1) Replacing spark plug hole seals if oil is present around the spark plugs
2) New spark plugs
3) Cleaning the MAF with contact cleaner or other suitable spray
4) Soldering the pre-cat oxygen sensors
5) Replacing your oldest coil pack assuming some of the four have been replaced in the past
6) Expensive options (problem should be identified first) i.e. new injectors and port cleaning
Limp mode due to throttle circuit error:
1) Check connector at throttle body
2) Check or replace connector at electronic throttle pedal
An electric window won't operate:
1) Swap the switches, drivers first, with ones that do work to see if it is the switch
2) Inspect, first by wiggling, the rubber door connectors. Then if you are keen get your soldering iron out and lots of fun or tinker around with other ideas.
A door speaker doesn't work all the time:
1) Inspect, first by wiggling, the rubber door connectors. Fix is the same as above.
2) If you have a Bose system, check the connector to the amplifier under the parcel tray.
1) Is there enough charge in the battery?
2) Does the code light turn off after one second, if not it could be an immobiliser issue.
3) Can you here the fuel pump, if not it could be the pump or 'in j' relay, inertia switch, ground wires e.t.c.
4) Check the ground wires at the battery and near the air intake
5) Use FiatECUScan to monitor the rpm, fuel pressure, injection time to see if anyone of those is reading zero whilst starting the car
6) Good luck
1) Get a code reader that is able or has been modified to connect to the airbag system.
2) For a squib error replace the connector under the seat or repair any broken or exposed wiring and then clear the code. Note the code will not clear if the problem is present.
Cleaning out the coolant reservoir:
Get some small nuts (no not an unwitting kid or midget), M6 would do and drop them inside the removed reservoir, immerse it in soapy water then vigorously shake it about.