ITB'd MK1
had a 172 in today with a rough idle. I'd changed the lambda around 2 months ago, and economy had improved, but the lumpy idle had got worse gradually. So, first port of call was the sparkplugs......sigh Bosch, fitted by a "specialist".....oh and they were loose. New NGKs fitted, better but not right, and lambda voltages were inconsistent so something fuel related going on. At this point I suspected an injector was starting to break down, so with the engine running I unplugged the injectors one at a time. NO DIFFERENCE. LOLWUT!!!!! it revved cleanly with only 3 injectors plugged in, and it was the same with repeating on all cylinders.
So at this point it seemed that although the injectors were operating fine under load, they were never fully shutting, so even with no electrical pulse from the ECU, there was enough fuel coming out to run the engine, and fairly well too. New one on me. and I couldn't believe i was seeing it, so chucked a spare set of used injectors on, and sure enough when i repeated the unplugging with engine running, one cylinder at a time obviously dropped out.
Result!! Never seen that one before though!
So at this point it seemed that although the injectors were operating fine under load, they were never fully shutting, so even with no electrical pulse from the ECU, there was enough fuel coming out to run the engine, and fairly well too. New one on me. and I couldn't believe i was seeing it, so chucked a spare set of used injectors on, and sure enough when i repeated the unplugging with engine running, one cylinder at a time obviously dropped out.
Result!! Never seen that one before though!
