Mystery of the ever increasing HC's

[bben76]

Test #1
Took the 'ole e30 to get the emissions tested, #fail. The hydrocarbons (hc) were about 20 ppm too high. I did some reading and discovered that HC's are really just unused fuel. I had stopped in for the test after the car had been running for only 5 minutes, so I thought because the mighty engine was not warmed up the rings/valves were not sealing up yet creating insufficient fuel burn.

Test #2
I figured a bottle of Guaranteed to Pass would help out, so I ran a bottle of it through and I went back after the engine was fully warm. I got a worse rating, now the HC's were about 40ppm too high.

Test #3
This last weekend I pulled the plugs and replaced them thinking fresh plugs couldn't hurt. I'm running Bosch platinum +4 plugs, btw are they any good? This time my HC's were even higher, about 60ppm too high.

wtf?

[James Crivellone]

what engine? M20's hate +4 Platinums, M42's don't mind them, M10's run on old sticks and bubblegum

EDIT: your profile shows an M20 ETA, yeah don't run those plugs. I've never seen an M20 run properly with them.

Bosch W8LCR, although you will probably need to get the W8LCR+ as Bosch discontinued the regular one.

[bben76]

Ah cool, thanks for the info. I'll switch out and see what happens.

[nrubenstein]

Or NGK ZGR5A, which is closer to the proper spec, now that the W8LCR has been discontinued.

Although, honestly, the cheapass Champions seem to work fine too.

[bben76]

I can look it up but I'm too lazy, what should they be gapped at?

[cunninglinguist]

Injectors could be leaking or FPR bad. Does the oil smell of fuel?
Change the oil and add to a low fuel tank some ethanol to lean the mixture, to the detriment of the Nx readings.

[zig553]

Yeah don't ever use platinums on an m20, I did on mine once and all it did was run rich. Bosch copper are the way to go.

[bben76]

cunninglinguist - what's the FPR? Fuel pressure regulator?

[AndrewBird]

^^^Yes.

Your O2 sensor could be bad/going out as well, which will cause the car to run rich.

[jlevie]

There are just too many possible causes of the rich condition to point to a single thing to tell you to do. Things to do to remedy the situation all mean putting the engine management system back to OE condition. For starters:

Use Bosch WL8CR+ plugs, or better yet NGK ZGR5A plugs
Replace the ignition wires, distributor cap & rotor with new OE parts
Replace the O2 sensor with a new OE part
Adjust the valves
Check the operation of the TPS and make sure the idle switch is working
Likewise for the ICV
If a 325e, check the cold start valve and sensors
Check the rail fuel pressure
Make sure the engine is running at normal temperature (~80c)
Check the data from the ECT sensor
Have a smoke test run and fix the leaks it reveals

If the engine still runs rich, have the injectors cleaned and flow tested. If it runs rich after that, replace the AFM, ICM (on a 325e), and DME. If it still shows as rich, replace the catalytic converters.