Thursday, September 20, 2007
The inspection sticker on the E36 was slated to expire this month so I decided to get up early and get the vehicle inspected today to avoid the typical end-of-month lines. I stopped by the dealer first to ask my technician to connect the GT1 and check for codes, just in case it had stored a code and not tripped the check engine light...as it had when it complained about catalyst efficiency late last year.
The goal in this case was to eliminate any possible reason for the state computer-based inspection process to fail me, as I don't know what the state computers consider a "passable fault" and a "failure fault". My technician suggested that the way OBD works is if the check engine light is not illuminated the car will pass inspection. I felt bad adding yet another item to his "run-queue" (the man runs around like the proverbial headless chicken in the morning, let me tell you) but five short minutes later I had my report -- no faults stored.
I threw my tech a tip to say thanks and headed off to the inspection facility where it passed with flying colors. The only notable difference between this and every other inspection the car has received was the compliment from the inspector about how clean the car looked. I guess they don't see too many of these older BMWs in the same condition.
Cold Start Issue Persists
While talking with my tech today I asked whether they had seen any recent flareups in problems relating to cold starts. He said he had seen quite a few cases caused by a failing check valve in the fuel pump (apparently they're susceptible to the alcohol in the new E10 contaminated fuels), but that was about it.
Not five seconds after my tech finished his sentence one of the other techs came up to discuss an '02 3 series that had been sent in for the same problem except the owner reported the engine wouldn't fire until he had cranked it for at least 25 seconds. BMWs solution to that problem was wiring related and from the looks of the service bulletin totally unrelated to my issue...especially considering my car starts just fine....it just takes a couple seconds of cranking during a cold start vs. immediate warm starts.
My tech suggested that it could be the check valve in the pump. I told him I'd already considered that and had tried to use the ignition key "trick" (to no avail) to make sure the fuel rail was pressurized. I cycled the key three times with about 5 seconds spent in position 2 each time, but he pointed out that one cycle of the key might not be enough to fully repressurize the rail and I'd have to wait about 2 minutes between key cycles in order to make the pump turn on again...otherwise cycling the key would have no effect on the pump and the pressure might still be too low.
To figure out if fuel pressure is the problem, I need to attach a fuel pressure gauge to the schrader valve on the end of the fuel rail, measure the pressure immediately following shutdown and then again after the car has sat overnight. If the pressure is noticeably lower, it's very likely either the check valve or a leak in a hoses somewhere. Which brings me to say that many techs, including Mike Miller of BMWCCA recommend wholesale replacement of BMW fuel lines every 10 years...and that wisdom was based on many years of running pure gasoline...not the alcohol blended fuels we run today. One of the reasons why alcohol is prohibited for use in standard certified aircraft is its deleterious effects on rubber, so the bottom line is that until all fuel lines in the BMW are swapped out with alcohol-compatible lines (assuming such alcohol-friendly rubber even exists), they are suspect.
For now the problem isn't enough of one to warrant a tizzy but I do plan to pick up an inexpensive fuel pressure gauge and figure out the extent of the job necessary to replace all rubber fuel line components.