[sand scorcher]

Thank you for the reply, well you have described my problem perfectly at your first lines, this is my case. Since I have installed in my car a scan gauge reader I can monitor live all engine parameters while driving, for the last ten years the blue light goes out exactly at 54 degrees, temp light operation is normal so I guess that my temp sensor operate correct.

''Other issues could be a possibility, that are fuel related or ignition; could be a possibility, dirty throttle body (clean and do a throttle body alignment recommended), low fuel pressure, failing coil, old plugs, etc. etc.''
I have recently replaced the ignition coil since it failed and I got the related fault codes. I have replaced spark plugs with no luck. Not sure about throttle body cleaning or low fuel press but I think that those could give me the same symptoms and above 20 degrees OT. But I will see what I can do about them. What is throttle body alignment?

''As for your MAF replacement; why did you replace it? Was there any related trouble codes; that would indicate it was faulty? It is best to monitor the MAF readings and that will indicate, if it is reading in spec. A replacement MAF, should be a oem BOSCH branded part; not a cheaper aftermarket MAF that will not work right, causing the car to run badly. If you have the old maf; you might reinstall it and see if the run any differently.''
One of the shops I visited he told me that I need to replace the MAF sensor because of the fault codes he had, I think the code was lean mixture or something but I don't remember. So I bought a new original Hitachi one as the one the car initially had but again with no luck. Then I visited another shop, they removed my new original MAF and test it with another one just to be sure but again no luck so my MAF is ok also I guess.
I was told that there is another ''cold'' sensor that read the intake cold air and that maybe this is the problem but I haven't checked that yet. On the other hand since I am able to reed the intake temp. I can tell you that this is stable and operate ok, on a cold day the intake temp is identical with the OT, as the engine gets hotter the intake temp also rises so this one also looks to be ok. I also run my car on LPG but this problem happens only at start up and only at gas operation, LPG operation is possible after 35 degrees water temp anyway.
Haven't checked my HAYNES manual to be honest but I will take a look if there is any ref in there.
Thomas

 

[sand scorcher]

I am in a process of testing my water temp sensor and MAG according to manual instructions, so far I have the correct readings regarding the hot range, I just have to make some pins to test it properly. The LPG system is the one you linked, it runs parallel or seperatly from the gas fuel system with its own computer, anyway while engine starting this is disengaged. As for the fuel trims you mention I have no idea about it. Guess I need a diagnostic tool and a computer to test or check it.
I'll report back when I have something new.

 

[sand scorcher]

I measured today WC temp sensor and found it within limits as per manual (but i have it on the list to replace it anyway) Reading the manual, i found that there is also a cold start valve attached to the fuel injection pump. It is responsible of advancing the the fuel ignition timing during cold starts and a problem of it causes unstable engine idle!! Since the Fuel injection pump has a pulley i guess it is somewhere lower in the engine perhaps under the air conditioning pump. So i guess i have to jack up the car and work underneath. Work for the weekend is scheduled so ill let you guys know.
PS i love working on my 1965 fiat 500 which relaxes me but i hate messing with modern cars because all this little small Satan devices!! The magic is lost here.
Thomas

 

[sand scorcher]

Maybe not, on a second thought fuel injection pump is for the diesel version, I don't think that this engine has it and manual does not specify this. As far as I know this engine is the same with the 2liter 8 valve.

 

[sand scorcher]

Thank you for the detailed info and your time. I have to add that I changed the water coolant temperature and things are a little better now. Idle is not that rough and no more unburned fuel smell. Backfiring is also reduced and all this unstable condition last for 5-10 secconds. I say that problem is reduced by 50-60% But is still here. I will try and find a diagnostic tool possible from eBay and see what I can catch.

 

[sand scorcher]

It's been more than two years since I started this post and finally got my hands on the problem and solve it. Removed the inlet manifold replace all o rings with new (old where hard as plastic) and seems like problem is gone, propably intake was sucking air until seals got hot and became enought soft to seal. Now i have very stable idle. In a case someone facing the same problem maybe you should try this first.