I wanted to start a new thread to make it clear, try to shed some light on what is going on with my 156 2.0 JTS from 2004 (177,000 km on the clock) and get some help of course !
Let's start with some facts :
- car was purchased in July 2011 with 152,000 km
- a leak in the flexi pipe has soon been discovered and part was changed,
- as coolant temp was always at 70°C, thermostat has been changed,
- after some misfires, I've changed all spark plugs and coil packs,
- to cure some mixture air/fuel problems, MAF has been changed and pre-cat O2 sensors have been soldered.
I'm pretty sure that most of the previous (bad thermostat, running with misfires, crazy pre-cat lambdas,...) while not solved by the previous owner has led the cats to cook.
When the cat started to rattle, I knew it had to be changed. That was 2 months 1/2 ago.
I've ordered a used genuine cat from Autolusso and had the cat fitted about 1 1/2 month ago. No rattle anymore.
Now the headache (Gosh, I really thought I could start enjoying the car...
) : the MCSF came on about 1 week after new cat had been fitted : P0420 (Catalytic Converter) & P0430 (Catalyser 2).
I thought this was some residues from the old cat, so I cleaned the errors and performed an ECU reset using FiatEcuScan.
MCSF came on again end of last week : P0420 & P0430 again...
I had a search on the web, and I've read a huge amount of threads about Alfa, BMW, Honda, Ford,... owners and what could be related with these codes. Dead cats come 1st, but people had success by changing O2 sensors, others changing the air filter, bad quality fuel could also be the cause,...
So I've plugged FES and decided to monitor the car's sensors, mostly pre and post O2 sensors. I've done this earlier this week, results are shown in the image "O2 with new cats".
Post-cat O2 are swinging up and down while they should be steady - as far as I've read so far.
I've also read that O2 sensors are binary : they work, or not. So if the signal changes, sensor is not dead. The fact that both sensors evolve in a similar manner leads me to think that they're ok.
I took the car on Monday for an exhaust gases testing. Here are the results, obtained with car at 3000 rpm, measures are taken during 30 sec :
- CO = 0.12% vol
- Lambda = 1
- CO2 = 15.24% vol
- HC = 26 ppm vol
- 02 = 0.1 % vol
- CO cor = 0.120 % vol
The exhaust guy told me these values are ok for a catalyzed car with pre and post lambdas.
Now the headache : what the hell is going on ??
1/ Is the new cat a lemon ?
2/ P0420 & P0430 are probably thrown since the post-O2 fluctuate so much. But why are they swinging so much ? Isn't the cat effective ? But why is the gas analysis correct ?
3/ Dan @ Autolusso (who has been very helpful so far - thanks) indicated that injectors could be leaking : I've thrown a bottle of Bardhal cleaner in gas tank today, but if we assume injectors are really leaking, shouldn't I get a mixture error thrown from the ECU ?
I've already spent a lot of money here, and the used cat didn't helped. So I need to understand if there is something else that should be changed or if the cats are really f#*!ed up !
Thanks for reading and for any help you might provide !