injectors dirty? how to diagnose?

[cro320]

What are the usual symptoms of dirty fuel injectors?

[Sagaris]

They will start sending you picture messages of them with their pintle caps removed and perhaps a text about how you are making their duty cycle increase.

[jlevie]

The most common symptom of dirty injectors is a rough idle. But since a rough idle can be caused by intake leaks, aged plugs/wires/distributor, aged O2 sensor, fuel pressure problem, valves out of adjustment, or a bad AFM, a rough idle doesn't necessarily mean injectors.

A smoke test of the intake will reveal any intake leaks and a check of rail pressure will tell if there's a problem there. Plugs, wires, and distributor should be replaced if they have significant age on them. A european can may not have an O2 sensor, but if it does and it has 160km on it the sensor needs to be replaced. Valves should be adjusted and it would be a good idea to run compression and leakdown tests to see if one or more cylinders are down on compression enough to cause misfires. With the other causes eliminated, the injectors move to the top of the list.

A DIY check is to pull the injectors & fuel rail, disconnect the coil, point the injectors into a towel, and crank the engine. Noticeable differences in the spray pattern or leaking from the injectors would indicate a need for cleaning and flow testing or replacement.

[cro320]

I replaced O2 sensor recently, engine runs smooth when hot but cold runs a little rough...so I suspect injectors

[jlevie]

Running rough when cold could be intake leaks, bad ECT sensor, or injectors. Since the engine runs smooth when warm, I'd say that intake leaks or a bad ECT are more likely than the injectors.

[cro320]

Running rough when cold could be intake leaks, bad ECT sensor, or injectors. Since the engine runs smooth when warm, I'd say that intake leaks or a bad ECT are more likely than the injectors.

what is ECT sensor?

[e30loverSC]

engine coolant temperature