Alfa 156 runs on 3 cylinder when cold

[MC-Racing]

Hello Alfisti!


My 156 2.0TS from 2000 with Motronic 1.5.5 has some problems with the engine, but this is a long story i would like to tell you. Maybe somebody can imagin what's causing the problems?

In December 2006 my timingbelt broke, all exhaust vlaves were twisted. We fixed it and smoothed the ports of the Head and the headers.
When i started the first time the new assembled engine, it idled about 1500 after a minute or two it lowered the idle speed to ~1200 a after some time it lowered once again the idle speed to ~900. When it reached 900rpm the engine started to sound strange with an exhaust note like american V8, one Cylinder misfired or didn't work properly. After an other minute or 2 it run like it should.
But always when i started the engine it starte fine, ran on 4 cyl but after a few seconds (exactly on the point when the cold start idlespeed is lowered to ~900-1000) it started to run on 3cyl.

In the laste Years I tried to find why ths strange behavior happens, so I changed..
spark plugs
MAF
Ignition Coils
Throttlebody potentiometer
Coolanttemperaturesensor
once again Headgasket
Lambdaprobe 2x

all changes with no succsess.

nearly every cold start, it doesn't depend on the weather or temperature (-15 to +35) it starts on 4cyl. after a some seconds in winter when i am de-icing the windows, when it comes down from the cold-fast-idle it only runs on 3cyl (V8 sound) for about 1-2minutes then every thing is fine. In Summer it starts fine on 4cyl. after 50meters i recognise that the engine suddenly looses power and sounds like a v8 after ~30sec-1minute the power comes back and the sound changes to 4cyl. But when we wave about +10°C dry weather everything is OK.

I hope somebody has an idea, wich cam help me.

Best Regards
Markus

[Erik]

Hi Markus - of all the checks you've made you haven't checked the fuel injectors and inlet manifold and its gasket for air leaks.
Erik

[MC-Racing]

Hi,

Oh, i have forgotten to list everthing i did.
I searched for air leaks, with no success.
The injectors have the right resistance and i cleaned it with brake-cleaner while i opened and closed it with a battery.
The cams are propperly adjusted with orig. camholders and micrometer for tdc.
I was in an Alfa Garage serval times checking the fault codes, and there were never faults saved.

And at the last, my 156 needs too much fuel, in the years befor the timing belt broke, it needed ~11L/100km but now it can't come under 14L/100km.
I am sure that the parts i changed were in good condition, mostly this things were changed with parts from my 145 2.0TS or my fathers 147 2.0TS.
My last ideas are that the ECU or its harness is faulty.
Or that the exhaustvalves are not sealing propperly, but if this should be the problem, then why sometimes it runs like it should.
But when ist warm its power is incredible for an 2L, it comes to Power ~3500 and revs up like a race engine, with orig 205/55/16 top speed is ~238 measured with GPS shortly before it reaches the revlimiter at 7200. The Limiter kicks in in 5th gear when i have enough time hold the throttle open.
Before i did the headwork including the header and the intakerunner it reached ist topspeed ~6000 in 5th which is around 210km/h.
And before tuning, when i measured a full acceleration run it needed from 100-160km/h ~ 17sec after tuning 13sec, int an german magazin they tested the 156 2.0 100-160 15sec, but this car had nothing inside no aircondition 15" wheels mine has everything what was on the pricelist, so my 156 should be much havier than the 156 in the test.

Please give me some ideas what i chould try to find the Problem.

Best regards
Markus

[Erik]

I think you ECU is in emergensy mode, usely it make the engine consume more 10-20% fuel.
This might cause the plugs to get wet in the start up fase.
My 180k km standard 2,0 is doing 8,5l/100 km, but I don't don't drive it as hard as you. It, too, have all the options on the list + 215/45-17" electric sun roof and engine heather.
Erik

[MC-Racing]

The 11L before and the 14+ now are not only from driving like in ETCC but from some short distances in Town.
Do you know how i can find out if/why my ECU is in emergency mode?
Should not a fault code appear in the ECU if it ist in emergency mode?
How can I reset the ECU at home?

Best regards
Markus

[Erik]

A fault readout can be done by Alfa or someone with the Bosch programme.
Yes, a light should be flashing or be on.
My consumption is short drives mostly, varies betwin 8,4 and 9,1 l/100km, a chips tune will most likely not affect the comsumption, didn't on an ealier 155 2,0 16v I had
Erik

[MC-Racing]

This is the problem, i was serval times in the local Alfa garage to readout the ECU, but there was never a fault stored.....
My Chip ist stock, but my header,head+intake are ported.

Markus

[euroscan]

hi,
- pls tell me number for this ECU M1.5.5
- i have alfa 156 ts 2.0 from 1999 with M1.5.5, my ecu's number is
0 261 204 948 firmware 1037359651 with G024
- i'll check my car with diagnostics soft alfadiag from this site
AlfaDiag Alfa Romeo Diagnostic Software
- i'll also try upgrade my software to MOD file , not only ORI file.
- cars working good and have power with cold engine.
-

[Peter]

I would also post this on AlfaOwner.com as there seems to be a lot more knowledge on the newer cars there

[rkbella33]

Hi I had a similar prob on my car with the same year...was also puffing black smoke with poor idling..had all the same trouble shooting done....if you look at the air intake manifold rear there is a fuel vapour return canister(?), and replacing it was like magic...I hope its the same...this is solenoid controlled and activates during idling...check it out swapping a known good used part ...hope this helps ....i checked eper and its marked as electro valve...part number as below

46469913 - ELECTRO-VALVE

[MC-Racing]

Hi,

@rkbella33, what would you think about this idea:
i disconnect und seal the fuelvapor-pipe on the intakerunner side and leave the pipe from the valve open ?
I think this should show me if the solenoid or the fuelvapor-pipe ist faulty if it runs good after the this change, or does it need the input of the fuel vapors?


Best regards
Markus

[rkbella33]

Quote:

Originally Posted by MC-Racing Hi, @rkbella33, what would you think about this idea: i disconnect und seal the fuelvapor-pipe on the intakerunner side and leave the pipe from the valve open ? I think this should show me if the solenoid or the fuelvapor-pipe ist faulty if it runs good after the this change, or does it need the input of the fuel vapors? Best regards Markus

[MC-Racing]

Quote:

Originally Posted by euroscan hi, - pls tell me number for this ECU M1.5.5 - i have alfa 156 ts 2.0 from 1999 with M1.5.5, my ecu's number is 0 261 204 948 firmware 1037359651 with G024 - i'll check my car with diagnostics soft alfadiag from this site AlfaDiag Alfa Romeo Diagnostic Software - i'll also try upgrade my software to MOD file , not only ORI file. - cars working good and have power with cold engine. -

[red_81]

Hi everyone!

TO rkbella33

I have exactly same problem as described. I tried to change canister (have one solenoid inside) but nothing happend (of course, after maf, plugs...). If I got it right, there should be another elektrovalve on the path to inlet manifold. Problem is I dont see it. Is it below? Could I se it from below the car? Wich wireing is provided to valve. If I know that I could measure resistance, or tried to connect it directly with 12V to conclude its faultyness.

Thanks in advance