P1402 P0121 P0113 & P0102 Codes on MG ZR TD+
Please help me. Here's my story...
ECU light came on about a month ago. Began running very lumpy at low rpm, but didn't really notice anything once I got going. Went to my usual guy, but he said it was an undocumented code and cleared it out. Light came back on after about 1/2mile.
As it has been getting progressively worse (more stuttery and black smoke) I booked it in for a T4 diagnostic. Car only just made it and I was down to a real crawl at times. The mech (Bob) suspected the EGR before he'd even connected it up and low & behold the code agreed (not sure what this one was; probably P1402).
HOWEVER, when he was revving it, I noticed the lower intercooler hose sucking right in! I knew this wasn't right as it has popped previously due to positive pressure. I replaced it 4/5 months ago.
So Bob opened up the air box and pulled out a carrier bag and a mangled air filter! Bingo! (so we thought). The filter element was duly replaced, the intercooler hose was now bulging rather than collapsing, and what he'd found was consistent with the symptoms and fault code. So, off I went a happy bunny.
Got about 3 miles down the road and when I tried to pull away from the lights it wouldn't accelerate and both ECU lights came on (one with and one without the exclamation mark). I was stuck in a fast idle condition, but as it's diesel, managed to get through the gears and return to the garage.
This time Bob found:
P1402 EGR-Actuator (Signal out of range. Too high)
P0121 Accelerator pedal sensor (ECU control line to pump solenoid shut off defective)
P0113 Air temperature sensor (Signal out of range. Too high)
P0102 Air flow sensor (Signal out of range. Too high)
He cleared the faults and revved the absolute @#*! out of it and it was fine, until I was about to set off, when the light came back on. Bob disconnected the EGR sensor and said that should get me home at least.
Well it nearly did. An hours drive across Brum in rush hour (about 15 miles) and got to the Chinese, no problem. Then when I pulled away from the Chinese, the fast-idle two-light scenerio returned (as I suspect code P0121 did too). So got it home on fast idle.
Now, how can I go from thinking the carrier bag was to blame to having all these faults!? Is one fault causing the others or do I need to take a look at wiring/connections?
Any advice on what I go for first?
Can I measure any signals with a multimeter?
Should disconnecting the EGR/MAF/MAP/whateveritscalled sensor (just after the air box) prove the sensor?
Can I test throttle sensor at all?