Decarboning of engine

[lolo888]

Hi All,

Has anyone had this done on their Alfa?
What exactly is it and is it worth doing?
What are the tell tale signs that your Alfa needs it?

thanks.

[colcol]

This used to be a big deal back in the days of FJ Holdens, when the fuel had a lot of lead in it and Carbs used to run too rich and you would get a build up of carbon on the valves, pistons and cylinder heads, that would cause pinging due to the carbon being red hot during the combustion process and this would cause uncontrolled igniting of the petrol, causing the sound of rattling marbles in your engine, in the olden days motorists would boast about how far their car could go before a 'decoke', but with modern injection systems, fuels and petrols and oils this has been made redundant, maybe you are driving your car like its a Toyota and you need to take it on a good run to blow out any cobwebs, Colin.

[lolo888]

thanks for that... i've been "giving" it a bit lately.. even took it for an extended long drvie (2hrs) and I'm still finding that 1st gear (under 2k rev range)
make the car stutter... this is the same for Reverse...so, it's not smooth when you give it just a tad of gas on first or reverese (especially when you're in a bit of an incline)... is this normal??

it's like when you drive a manual car and you don't give it enough gas, it makes the car hesitate... (if that makes sense)..

i was told it may need decarboning (which is common with JTS's)... or could it be the coil packs??
it's my first alfa... i don't think i've lost any performance (hard to tell though as i don't have anything to benchmark against)... petrol consumption seems ok... i'm getting 9litre/100km

any ideas on what the issue may be?

[colcol]

I don't think it would be a coil pack as they seem to either work or not and if one coil stops working you are down 25 percent power, which you would know about, some of the early 156 JTS's had a problem with carbon build up, but yours is a 159, it may be a mass airflow meter on the way out, Colin.

[lolo888]

thank for that clarification.. not the coil pack then...actually, I have a 2005 GT (JTS)...
hhmmm... might bring it to the Alfa doctor... even in idle the engine is a bit noisy (almost like a diesel)...

i heard decarboning cost close to 1k...

[colcol]

So yours is a 932 based car, like a 2 door version of the 156, if it is a bit down on power and it sounds a bit like a diesel, then it could be a camshaft variator, this device alters the solid position of the cam, a British car specialist told me on his marque, sometimes putting the correct oil in can sometimes get the variators working again, if your JTS has got the correct clean oil in it, then its most likely a variator, as they don't last forever and can make the car loose 20 gee-gees,  or it could be that it does need decarbonating, but i was told it was only the early JTS's 2002 MY that suuffered from this problem, Colin.

[wankski]

this low end stutter is a mapping problem on the early 2.2jts and is well known in the UK.... search the alfaowner forums and you'll uncover some info on it

[wankski]

here you go:

http://www.alfaowner.com/Forum/alfa-159-brera-and-946-spider/114153-2-2-jts-hesitation-now-new-important-information-and-escalation.html

[Jekyll and Hyde]

this low end stutter is a mapping problem on the early 2.2jts and is well known in the UK.... search the alfaowner forums and you'll uncover some info on it

What exactly does the 2.2JTS in a 159/Brera have to do with the 2.0JTS as fitted to a GT?

[colcol]

He has a 2005 GT JTS, it in the wrong section, this is for current models only, Colin.

[lolo888]

He has a 2005 GT JTS, it in the wrong section, this is for current models only, Colin.

ooppss.. sorry guys... is a 2005 GT JTS a 932 series?
I saw GT on the title of this section so i thought this was it   

[wankski]

ahh, whoops, missed that...