That's very useful information! I have same problem. But after one week my alternator died. By the way - it's very difficult to change alternator! ;-( today i'll put restored alternator back and i hope second problem will be resolved

What and where is the IAC valve?

It's a valve that controls the idle speed and engine breaking force when you lift the throttle. It basically bypasses the throttle to allow a small amount of air into the engine even when you lift the throttle fully.
It's located on the intake side near the throttle body and it looks like this:

http://g03.a.alicdn.com/kf/HTB1sGnW...A-LANCIA-DEDRA-60608904-6NW009141-091-X10.jpg

It's mounted with two bolts and connected with a 2-pin connector.

HP said:

Not sure if this helps, but...

Mine had a tendancy to almost stall when slowing for junctions and a slight hesitancy on acceleration. Not a major hiccup, just a slight running weak feel. The idle could occasionally dip as well.

Had the injectors refurbished, slight improvement.
Changed the fuel filter, slight improvement.
Changed the fuel pump today - bingo!

Idles better, no weak running and although it still had loads of power it probably has about 10% more now

Click to expand...

Although mine is now locked up for winter, i have noticed it would stall when breaking after a steep descent or braking hard. As i do less than 1000 miles a year in it, it was not really me worh investigating.
I think i'll give it a full service over winter and that may help for when it comes out again in May.

My Barchetta did exactly this last night. Wouldn't idle steady, and was trying to stall when stationary. It did stall as I stopped to reverse into the drive. Tried the car 20 mins later and the idle was fine. Fine again this morning on start up, although it will get a decent drive today...

Looks like some investigation is needed.

the only way I fixed the problem was with poring in redex stuff and driving for around 200km. seems like just something was clogged, I Pretty much dismantled half of the cars engine/cleaned everything, changed Idle air control valve as well, did no effect.
Only the redex helped.

itaa5x said:

the only way I fixed the problem was with poring in redex stuff and driving for around 200km. seems like just something was clogged, I Pretty much dismantled half of the cars engine/cleaned everything, changed Idle air control valve as well, did no effect.
Only the redex helped.

Click to expand...

Thanks. The first thing I did was get some Redex and the air control has been cleaned out (that clean made no difference). Will give it a few miles with Redex and some decent fuel before panicking too much.

Hi,
Has it worked?
SteveD

Silly question, what should the revs be at idle?

900-1000rpm when warm.

Ilkka said:

900-1000rpm when warm.

Click to expand...

Ta, I was worrying mine was idling too low.

So after several weeks of no improvement, I bought a new IAC valve. Not expensive. Thought I'd solved it, went well for a few miles.. but now it really is all over the place! Perhaps need to disconnect the battery and start again.

I purchased my 98 Barchetta,( imported from Japan)last fall with just over 21K on the clock. I drove it for a couple of days in order to put fresh gas in it. On one particular day it started fine but quit on me about two kilometers from home.I tried to start it a few times,it would start, run like crap for a minute and then quit. I walked home in order to call a tow truck then walked back to the car to wait. the thing started and ran mint. I then drove into town to a good friend who owns a top notch European repair shop. Just as I got there it ran like crap again.He hooked up the engine scanner to it while it sat there wheezing, coughing, and near stalling for 30 minutes. He could find no reason for the terrible idle. Suddenly it started running normal and has done so since. That engine has a compression ratio a smidge over 10.3,which is fairly high for a four banger.I always run high test gas now,91 octane or better,so far so good.

Interesting
Here the lowest octane gas we have is 95 and then the 98 !!
91 octane gas it can get nocking !!

Dan Friel said:

So after several weeks of no improvement, I bought a new IAC valve. Not expensive. Thought I'd solved it, went well for a few miles.. but now it really is all over the place! Perhaps need to disconnect the battery and start again.

Click to expand...

haha I had bought one of those as well think for like 15euro, it only made the car run worse... just cleaned the old one.

That's really strange re;fuel octane. the highest we have here in the Toronto GTA is 94 which is not easy to find. Some of the ESSO , stations have it. But I have never heard my engine knock or ping which were quite common problems years ago before gas was treated with special additives.Where do you live

searching in wikipédia i found out , there are at least 3 diferent scales (ways) of classifiing octane in gasoline : MON ; RON ; IAD
depending on the country , so i think in canada they use the IAD scale , in europe the RON scale ...

so :
87 IAD » 95 RON

93 IAD » 98 RON

Some progress.. The IAC valve change seemed to do nothing much for the situation. However, the temperature sensor has now been changed, plus the throttle position sensor checked and re-set. Battery disconnect for 30 mins.... and it's now "ok" on idle.

I shall be putting some decent miles on the car, and see what happens.

Dan Friel said:

Some progress.. The IAC valve change seemed to do nothing much for the situation. However, the temperature sensor has now been changed, plus the throttle position sensor checked and re-set. Battery disconnect for 30 mins.... and it's now "ok" on idle.

I shall be putting some decent miles on the car, and see what happens.

Click to expand...

Still going "ok". Fingers crossed that the change of sensors and reset has worked.

Hi Dan, is your B. still running fine after the temperature sensor replacement?

I have been struggling for some time with my B. having slightly rough warm idle. The cold idle is smooth and nice, once it gets warm there is something going on. The RPMs seem to be steady on the gauge and the indicator seem to barely wobble at the idle around 900 RPM. However there is a noticeable engine vibration transferred to the chassis and you can hear the exhaust sound to be somewhat irregular. I should also add there is no noticeable power loss and other effects that would suggest something going on with fuel pump, injectors etc. (or am I wrong?)

So far, I have:
1- cleaned the ICV - not much to clean in my opinion, had to change the gasket too, the old one seemed to be worn and I might have torn it while disassembling, there was some dust in the air channels in the throttle body though - not much
2- cleaned the throttle body - same here, I did not see much to clean, so decided not to disassemble it
3- cleaned the MAF - the wires were a bit dark and after cleaning with a brush and acetone I was able to bring them to as new condition
4- looked for vacuum leaks - well I was not able to find any, I have disassembled the rubber hose from the MAF to throttle body, sealed it, filled with water and found no leaks, at the same time I have cleaned the vacuum lines going from rocker cover to the throttle body and the hose itself. The lines were dirty with a bit of goo which I got rid of
5- changed spark plugs
6- checked ignition coils - uplugged one by one and observed whether they had the same impact on the engine run at warm idle - and they all seemed to do the same -

The other stuff I think of are the O2 sensor going bad or temperature sensor getting mad at warm. The temperature sensor resistance was ok at room temperature but I have not measured it at warm condition.

Do you guys have any more ideas what to check? I am interested in your experience.