injector leak sensing

[gotgarth]

1991 m30 non california. my car is not set up to receive injector leak codes, and i was wondering how does the california system reads a leaking injector? in other words, how does it know an injector is leaking?

[Q45tech]

ECU monitors each O2 dividing into banks thus 3 exhaust pulses make up the totality of that bank if one bank is normal and the other rich it is assumed to be cause by an injector leak.

More modern ecu and wideband O2 are able to resolve this down to a single cylinder just as they do with a cylinder misfire.

A leak might just be rich while a misfire is super rich on that cylinder.

Worn out sluggish O2 [50-60k in early engines and 100k in later units] will fool ecu because they don't have time to react to a single cylinder.

[goody90q45]

......i was wondering how does the california system reads a leaking injector? in other words, how does it know an injector is leaking?

What I think Tech was saying was if you've pulled the ECU codes and you got the leaky injector code (45 or 51?), the most likely culprit is bad O2 sensors. Bad O2 sensors are like high blood pressure- you feel normal and don't know you've got it. Time to replace them. Worst case is you really do have a leaky injector, running rich, etc., and are sending raw fuel through the exhaust but there's other obvious symptoms that would go along with it.

[gotgarth]

thanks guys. i just bought a california computer and would like to connect it to see what errors i get. my computer gives no errors (55). but since having the car 2 years now (91 m30) i'm only getting 10mpg tops. been using low grade fuel 2 years, but now getting heavy hesitation with it. high grade is better but still hesitates. when i use software to cut cylinder 6 it idles better than when i turn any other cylinder off. 6th plug had black soot. and i hear occasional put put sounds from exhaust at idle. replaced o2 early on but didn't help and then i found out the car has self diags available. but i'm way past that and looking to replace all 6 injectors. 137k miles. since i only have street parking here in ny, i'm afraid to take anything apart and get stranded on the street getting parking tickets galore.