Alfa Romeo Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter #1 (Edited)
Hello guys, i have some problems with idle on my beloved car. It has some vibrations when idling, it sometimes wants to cut out when i depress the clutch while moving. It also has fuel smell from the exhaust and produces quite lot of steam. Things i've done so far - new coils and plugs. new Bosch maf, new Bosch o2 sensor, new breather Valve, replaced throttle body for 3 different ones, sealed exhaust leaks, checked all intake for leaks, checked evap Valve, checked timing with OEM alfa camlocks and tdc gauge. I've ran compression test ~ 14bar on every cylinder. i've tested for head gasket failure, IT is good. I can rule out any injector leaks cause my car is LPG converted and i can see no difference when running on LPG. Temperature sensor is good aswell. My bet is on overfueling, but i have no idea what causes it. Only thing i've noticed odd are air intake temperature - IT shows 20°C when outside temp is about 5°C(replaced maf for 3 different ones with no luck) and my lambda reading never go lower than 0.3v. any ideas what can cause behavior like that? Any help appreciated ;) MES screenshots attached(one with higher maf was lights and other equipment on, one with lower one only stereo playing, both taken with engine temp>84°C)
 

Attachments

·
Registered
Joined
·
26 Posts
Discussion Starter #2
Guys im really desperate for help, I have some ideas what to do with the car, but most od them involving lake and a cliff ;)
 

·
Registered
Joined
·
2,550 Posts
+0.3 volts on O2 sensor is probably a bit on the high side. Does the car run LPG at idle?

Have you had car emissions tested?
Has the cooling system been tested for combustion cases by coloured fluid or by exhaust gas analyser?
Where does the steam come from?
Have you sprayed brake cleaner around where injectors and gas nozzles fit into inlet manifold (and around other seals and gaskets)?
 

·
Registered
Joined
·
26 Posts
Discussion Starter #4
Thanks for the reply. There is no difference between running on petrol or LPG, parameters are pretty much the same. I havent tested emissions, head gasket was checked with fluid(coolant level is stable, i don't have to top up). I havent sprayed brake cleaner near injector nozzles. Is it worth trying? Car would run that rich if it was leaking near injector nozzle?
 

·
Registered
Joined
·
2,550 Posts
Spraying a combustible liquid around the inlet manifold would show up as the engine picking up and running roughly or possibly even knocking if there are any air leaks. Were there any differences between spark plugs when they were removed?

I realise you have checked the cam timing. It really is absolutely critical on the 24v Busso. Even a fraction off and it will run like crap at idle. Anyway, what you suggest means it cannot be a fuelling issue. However and air leak or cam timing seems likely. Are you ears good enough to determine whether it is in just one cylinder or more than one cylinder? I find it is the cam timing on the rear bank which is where idle issues usually manifest.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #6
Today i've checked for air leaks, no luck, so there must be something else wrong. Cam timing you reckon? Would broken camshaft cause something similar?
 

·
Registered
Joined
·
360 Posts
Have a look at these couple of threads about idle problems with the V6.

Both are CF2 engines, so it might be relevant

They disassembled and cleaned the control unit wiper tracks of the throttle body very carefully.

Despite replacing the Throttle body units, unless they are brand new they are probably all about the same age and all need a good cleaning.


 

·
Registered
Joined
·
26 Posts
Discussion Starter #8
After i did what mentioned in above posts, the idle is better, but not perfect. I guess timing then...
 

·
Registered
Joined
·
26 Posts
Discussion Starter #9
Little update, i've double checked timing using OEM camlocks and tdc gauge, replaced throttle potentiometer, both camsensor and cranksensor, checked wiring and problem persist. This is really hopeless case... I've run out of ideas. What is freaking wrong? Why is the damn car overfueling itself? Why injection times on idle are ~ 4ms? Any ideas are welcome as i'm desperate for any help.
 

·
Registered
Joined
·
360 Posts
How is the idle not perfect now?

Is it high, low, or not as smooth as you would think? When my v6 is at idle the rev counter is steady, but I can feel the engine idling through my seat. I am under the belief it is normal being a engine in V6 configuration, but I could be wrong. When accelerating the power is smooth however.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #11
If vibrations are normal, its ok, but why on earth idle bounces when i depress the clutch coming to a stop? It drops to about 400 RPM(i feel power steering is dissapearing) then bounces back to normal idle speed, sometimes when coasting on neutral idle is unstable (IT varies between 1000-400rpm)until i come to a complete stop.
 
1 - 11 of 11 Posts
Top