new guy e28 M5 running rich?

[markwascher]

Hello, this is my first post.

My e28 M5 (145k) which I bought a month ago seems to be emitting unburned gases. My garage smells like an ether factory. I recently fixed a fuel line coming out of the fuel filter by the gas tank (no leaks)and replaced a "rebreather"??? hose from the airbox that winds its way down and to the left between the throttle bodies. I had to take all the "trumpets"?? off the throttle assembly to get my fingers under there. The throttle plates look a little carmalized and there was a dab of oil on each of the ports.

All but one of the rubber O - rings looked good. I cleaned the seats and lubed the o - rings with a thin film of oil before reattaching. I think I got the hoses pretty tight.

The car smelled rich before the work but I didnt think anything of it. Am I paranoid about missing somthing? yes? Could it be that I have a bad exhaust valve? I am not much of a mechanic but I try. I have pictures but I cant figure out how to post them. Guess I'm not much of a computer guy either.

Also I seem to have lost 1mpg since the work.



Any help is much appreciated.

[Mark_88_M5]

rail? You may have a failed fuel pressure regulator.

[antony]

hi mark,

a fuel pressure regulator failed in the "too high" pressure mode will most likely cause the trip computer to register unrealistically optimistic mileage.

i'd check your afm for signs of tampering; one smog shop i went to
adjusted mine way out of whack. if that's the case with yours as well, good luck trying to put it back. it may also just be worn out. i'd also check your o2 sensor output for proper function, although with everything else in good shape, that should not make all that much difference.

congrats on your purchase; i'm sure it will provide years of entertainment.

--antony

p.s. if you (or anyone else) is interested in a dinan or tms/conforti ecu chip, i have both available (i just installed one of scottie sharp's maf conversion kits).

[antony]

you might also check the air and coolant temperature sensors.

--antony

[lkfosteraz]

I've had my M5 run rich when I didn't replace the gaskets between the headers and the catalytic converter after I replaced my driveshaft. That allowed air to get sucked into the exhaust, which in turn told the oxygen sensor circuit to go rich.

[Todd Frye]

I would think the emissions print out from your state inspection would list a specific percentage of hydrocarbons and CO2. This would be a known starting point to diagnose incomplete combustion. Did you get a compression and leak-down test before you purchased your M5? These tests also give very important info on engine health. Pull your spark plugs after a decent warm-up drive, and evaluate: white/lean, light chocolate brown/good, crusty black/not good. Use the plug wrench in your tool kit for plug removal. It works just fine. Start with the basics and hopefully that will get you pointed in the right direction. Good luck. Todd Frye

[markwascher]

Thanks for all the advice. I had it smogged and everything is cool. A leak down test done prior to purchase showed pretty good results with the largest loss of 14 on number six. the rest were around 10-12. I'll check the plugs next.

Have a good one everybody.

[ajwong]

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