Fault code 1226!

[Tim Polzin]

OK, an earlier problem seems to have returned. Car is a 95 318i with manual transmission.

Symptoms include mid throttle hesitation/stumble when warming up, usually not present when engine is warmed up, nor when it is first started, only as it warms. When occurning, idle is a little slow and unsteady, occasionally could die, otherwise it is rock solid. Wide open throttle is never affected. CEL will come on very occasionally and fault code reads 1226, #2 knock sensor.

The problem occasionally also appears in the rain and a warm engine.

Based on some reading, suggestions include replacing O2 sensor, plugs, cleaning contacts on DME, reseating #2 knock sensor, etc.

Based on the the occurance in the rain, I'm wondering about the O2 sensor.

Any suggestions?

Tim

[Jeron]

Wet ECU/ECM may be your rain problem. It's common so you shouldn't have trouble finding info on it here or elsewhere on the web.

For the other suggestions, you can do them all except O2 for the cost of plugs.

[Tim Polzin]

Thanks for the suggestion Jeron. I will do the plugs and check connectors. The impact from wetness seems to be more to do with a wet road rather than from rain itself. Around here, wetness is rarely an issue. As well, the car spends most of it's time in my garage, and still will (not always) exhibit the problem as it warms. Does not normally appear when up to operating temps, or when cold.

Tim

[Tim Polzin]

Maybe I found the problem.

The fault code moved from 1226 (knock sensor #2) to a constant 1286 and the other problems went away (go figure). I replaced the #2 knock sensor (major pain) with no impact on the fault code.

So I pulled and disassembled the ECU and closely examined the solder joins at the connector. A few were suspect, so I reflowed solder on all the connector joins and other large component joins.

So far, just 1444 (no faults) has come up. I'm hoping for the best.

Just to comment, the ECU compartment was completely dry with no evidence of ever getting wet.

Tim

[Wayne 962]

Yes, that knock sensor requires the removal of the intake manifold = major pain.

-Wayne

[Tim Polzin]

Originally posted by Wayne at Pelican Parts
Yes, that knock sensor requires the removal of the intake manifold = major pain.

-Wayne

Actually, you CAN do it with only taking the top half of the intake manifold off, with a combination of 1/4 and 3/8 drive extensions and universals, still major pain.

Still no fault codes and over 1000 km!

Tim