HELP! Heavy white smoke out tailpipes – smells like gas (not coolant)

[thesalboy]

2003 X5 4.4i (M62tu) automatic. It ran great before I started this 100K overhaul. At my wit’s end.

I serviced the valley pan, and while at it did valve cover gaskets, intake manifold gaskets (all internal and mating surfaces), oil separator, PCV/CCV/EGR (on back of intake), and had injectors serviced at Mr. Injector. I also changed the fuel filter, which has the fuel pressure regulator integrated into it. Also changed plugs – I used Bosch 4417 (FGR7DPQ).

Immediately on startup, light white smoke started coming out of only the right tailpipe. The smoke quickly thickened. The engine also had a miss – I think only on the right bank. Left tailpipe seemed fine – no smoke, no miss present. I let it idle to warm up the motor, revving it a little occasionally, but the smoke stayed thick and the miss was there at all RPM ranges. I shut it off after 10-15 minutes.

No SES/CE light ever came on. I checked codes and it showed only one: P0134 - 02 Sensor Circuit No Activity Detected (Bank I Sensor 1). I believe this is a symptom not a cause – the first O2 sensor on the right bank is flooded with gas and may now not operate at all. I have not since run it more than a few seconds as I tested, but there are no codes coming up, much less a SES/CE light.

There is no hint of coolant smell to the white smoke. It appears to be unburnt fuel vaporized by the catalytic converter. When I ran it for a while, the right tailpipe was moist and the moisture smelled like fuel. Oil smells a little like fuel.

In desperation, I replaced all injectors with brand new. The smoke now comes out of both tailpipes equally. As in the beginning, the smoke is light at first, but thickens quickly.

TESTS AND RESULTS

I switched the two lines on the fuel filter to make sure I didn’t get them mixed up. The car started and ran for a few seconds before dying. This is consistent with my understanding that the car would not run if the lines are switched – it ran after switching only on residual fuel pressure. I switched the lines back and the smoke returned. [Beware – there are DIY posts out there mixing up the ports on the filter. Blue lines indicate fuel flowing away from the filter – return or engine feed. The black line feeds the filter.]

I sealed off the throttle body with a plastic bag and hose clamp, pulled off the evap hose on the side of the intake manifold, connected a spare hose and blew into it to pressurize the manifold. Air only came out of the plastic pipe that goes from the intake boot to the EGR/brake booster one-way valve – once I capped that (and the hose I blew into) no air came out until I released a hose. I was concerned an intake manifold gasket had fallen out of place during install, but this seems to confirm there is no leak in any of the intake manifold seals.

I pulled the engine harness off the injectors and cranked the motor with a test light in each fuel injector port. Each acted the same – after some cranking the light started flashing, a little faster than once per second. Other cars have reacted differently, flashing more rapidly. Not sure if my results indicate a problem or not – not covered in Bentley.

Fuel pressure is normal – 3.5 bar at the Schrader valve on the rail.

As this point I have to suspect the DME, but am hoping someone has an idea of what else it could be.