Technical GP T-Jet not running right, coughing and rough idle

[misk]

Hello everyone,

I have a problem with what I suspect to be the AFR causing my Punto to not run right. Just over a month ago I got my post-cat lambda sensor replaced due to a check engine light showing up with code P0130(no issues other than the check engine). The next day after getting the sensor replaced, the check engine came back with codes P0130 and P0136, the other lambda sensor (which I got replaced at the same garage a few months previous). I returned the car to the garage to rectify this issue and I got the car back supposedly fixed however on the drive home the car was behaving strangely. It had a rough idle (stalled itself at a stop twice), and at circa 2000 RPM while the boost was building it was like there was no acceleration at all before the car would cough and accelerate forwards at a jolt. The check engine came back on and codes P0130, P1141, and P1135 showed up. I then returned the car to the garage again, and got it back after they supposedly fixed it by soldering it? (it later came up in conversation that this sensor wasn't an OEM replacement but rather a universal one). I brought the car back and got it back supposedly working as the mechanic had supposedly driven it and it was fine, however the same thing happened where the car would jolt and stutter and the same codes would come back after a short drive. I have brought it back and got it back numerous times with an identical situation happening, even after they claimed they had replaced the sensor with an OEM one. They now claim that it's a problem with the ECU, and advised me to contact an electrician (paying out of pocket obviously).

Has anyone got any idea what might be wrong?

 

[GrandePunto PL]

Anything related to the combustion process = go to MOT station and take an exhaust test (gas analysis only, as a diagnostics, not as a "MOT", so you can fail it without consequences and drive away).
Clown world we living. Mechanics can't do BASIC electrical checks: power (battery, alternator), connections (corrosion: main ground, fuse/relay box).
Too much electrical issues at once (suspicious): gas pedal, oxygen sensors/heaters, ECU and something about "fuel restriction"? Weird combo.
Many times faulty ECU will not report any errors. But ECU with bad power supply will throw silly codes...
As for OBD2, use Fiat dedicated software (FES, MES, AlfaOBD), free universal scanners are useless.
OBD2 is designed to diagnose a car: means, you analyze the parameters, take a data logs (test drive). Erasing fault codes is not "repair".
Are you equipped to perform basic checks? Like an oil pressure, fuel pressure, intake air pressure/boost, compression? And electrical (multimeter at least?).
Warning about multimeter checks: you can ruin a good plug/socket by pushing probes hard, forcing them into connector. Watch out.
Original sensors: yes. Don't use cheap replacements (and definitely avoid "no name" ones).