I've seen the o-ring issue myself.
My buddy had a pump failure on a road trip, and my used replacement pump o-ring wasn't in very good shape, so we re-used his. Didn't have any vaseline (the recommended o-ring lube), so we just kind of used residual fuel. The pump went on hard, and so we both knew it was a temporary solution...(
which he drove on for 6 months
, before he got enough beer available to accurately troubleshoot this issue...
) Checking the fuel pressure was all it took to nail the problem down.
As far as the temp senders go, you're styling if you got a logger
With everything stone cold, the iat and ect should match.
When you light the car, the ect will increase fairly rapidly, and the iat will hardy change at first. After a bit the car will reach operating temp. The ect will be 180~190ish, (maybe even ~200, but not much more) and the iat will have increased ~some~(sorry, a lot of variables affect the iat)
(I don't want to misinform you, because I don't have a cool guy datalogger, (
) so I haven't really tracked my own car much, but *generally* with the hood open, the iat won't change much, whereas, idling, with the hood closed on a hot day, it will change a bunch.)
It's measuring intake air temp, so I think you could just make a reasonable approximation, and be close enough. If you wanted to get all scientifical, I 'spose you could shoot the air can with an infrared temp gun...but I think close is ok, because it's more of a secondary imput for fuel trims. Imho, comparing iat and ect, cold, is enough verification that it's in the ballpark, unless the iat reads elleventy kerbillion * at operating temp.
The ect, on the other hand, is a
major player in the calculated fuel trim. The ecu will add fuel to a cold motor, based on ect, and will gradually taper the cold fuel enrichment down, relative to ect input. When closed loop is obtained, the ecu will trim everything up much nicer, using measured feedback from the o2. To some extent, the ecu can trim out the affects of a slightly out of range ect this way.
These cars seem to have issues with the harness wires right at the ect plug, so if your ect numbers are kinky, I'd go there first, before I replaced the ect sensor itself. As the individual wire strands break, one by one, they gradually skew the ect reading to the ecu, but not enough to set the check engine light, or keep the car from starting, just enough to cause issues like this...(It is a dsm
after all, and they like to be sure that we're paying the proper attention to them...so they just beg for attention in strange 'n unique ways..
)
One other thing you might want to check is the barometric sensor reading, (also in the airflow sensor.) It should read a reasonable facismile of the barometric pressure for your altitude, on that day, and shouldn't change much as you drive. (unless your commute is uphill/downhill +/-3500, each way, like mine..
..) It is also more of secondary fuel trim input to the ecu, but it can throw things off enough to get the car to run funky cold, and yet still enable the ecu to trim it out when in closed loop, and warm.
Track your battery voltage as well, a weak battery could cause some funky driveability when the system runs at low voltage, after the car runs for a while, the voltage could recover enough to make everything run smoothly
Good luck, with a datalogger, and your accurate posts/info, I know you're going to solve this problem, and help some other people who read this thread along the way.
