I have a Transport 98 with just over 100,000 miles. About mid 2004, the
"Service engine soon" light when on. With an OBD II DTC reader, I was seeing
the DTCs corresponding to "cylinder misfires" set. I discovered then that
the injectors were getting stuck (I assume close). I discovered also how to
get them unstuck by removing temporarily the fuse associated with the
injectors and then applying voltage on and off to the injector that was
causing the misfire until I hear it clicking. Initially, I did that once and
did not have any problems for several weeks. The problem got progressively
worst having sometime multiple cylinder misfires. I had to carry a couple of
9 volt batteries (which I put in series), so I could unstuck the injectors
while I was away from home..
Eventually, I got tired of unstucking the injectors and decided to replace
them all. That was in October 2004. After that I did not have any problems
until December 2004. The temperature got colder. I am in the Chicago area. I
am not sure if there is any correlation with the temperature.
I started wondering myself whether the fuel pressure have anything to do
with my problem and started doing some experiments. I found that by
releasing the pressure using the corresponding valve, I could get unstuck
whatever injector was stuck much more easily when I applied voltage to its
terminals. I started suspecting of the the fuel pressure regulator and
replaced it. Initially, I thought the problem was gone because I did not see
the problem recurring after several engine starts during the day, but then
it came back the same day I installed the pressure regulator. So I do not
beleive replacing the pressure regulator helped at all. I also mesured the
fuel pressure before and after replacing the fuel pressure regulator and the
pressure seems to be within specifications between 41 and 47 PSI.
Currently, my situation is exactly the same as in mid 2004. I have single
cylinder misfires and sometimes multiple cylinder misfires. Sometimes the
engine starts perfectly fine--if my prayers work ;-). Sometimes it starts
with a misfire. When the engine starts fine it remains fine (no misfires and
smooth ride). When the engine starts with misfires, it remains misfiring;
very rarely it recovers by accelerating .
I got more sophisticated though in recovering from the failure. I discovered
that by disconnecting the fuel pump fuse while the engine is running and
plugging the fuse back in before the engine stalled, I could recover easily
from the failure. Now it takes me a few seconds to recover from the failure
and I do not need to carry 9 volt batteries. I am even considering putting a
switch inside the cabin to control power to the fuel pump in a more
confortable manner without the need to open the hood.
In addition to have replaced the injectors and the fuel pressure regulator,
I have replaced periodically the spark plugs, the fuel filter, the PCV
valve, the spark plug cables, and the oxygen sensors. I also periodically
have used fuel injector cleaner.
Some potential suspects I have in mind are
- the engine control module (maybe the injector drivers are bad),
- the fuel pump,
- bad quality injectors (the ones I installed are AC Delco),
- the battery (not sure how it will relate to the problem, but it is
almost as old as the van)
- dirty fuel (perhaps the fuel tank itself is dirty)
I have considered getting rid of the van, but I have spent some money and
time installing DVD player, a 17 inch display, a TV tuner, and satellite
radio. I would like to hang on to the van for a little longer. Everything
else is in good shape.
Any ideas (beside the fuel pump cutoff switch inside cabin or getting rid of
the van) will be greatly appreciated.