W204 ecu

Page may contain affiliate links. Please see terms for details.
D

Deleted member 65149

Guest
I suspect a dirty connector somewhere relating to the ECU and want to simply try removing and reconnecting everything electrical associated with the engine that I can see. But before doing so, am I likely to upset anything that will need Star to reset?

The issue I'm getting is very high fuel consumption during the first hour or so of a journey. If I stop and leave the car, even for a couple of hours, then return the consumption gets back to something like normal. In fault mode it's getting down to as low as half the normal figure. That's why I suspect a dirty connector, possibly from a sensor to the ECU, that "cleans up" during use. Removing and replacing the connectors may suffice as a cure. The problem is that the car is usually left unused 3 or 4 days a week, often only completing very short journeys in between.

Realistic thoughts appreciated before I go making matters worse.
 
"the car is usually left unused 3 or 4 days a week, often only completing very short journeys in between."

"very high fuel consumption during the first hour or so of a journey."

Slightly confusing usage?

Also how would using the car, then leaving it a couple of hours resolve a dirty connection?

Has this high consumption only come on recently, possibly with the colder mornings?
 
whitenemesis said:
"the car is usually left unused 3 or 4 days a week, often only completing very short journeys in between." "very high fuel consumption during the first hour or so of a journey." Slightly confusing usage? Also how would using the car, then leaving it a couple of hours resolve a dirty connection? Has this high consumption only come on recently, possibly with the colder mornings?
Sorry, I wasn't clear. I think the connector problem may be due to the car not be used daily, so possibly a corrosion issue. Just a thought. The very high fuel consumption occurs on all the short journeys, but it's most noticeable when cruising at motorway speeds during occasional long journeys when it's only an indicated average 20mpg instead of the normal 40mpg. There's no way I'd expect that sort of difference due to a cold morning (the coolant gets up to normal temperature as fast as expected).
 
Sorry, I wasn't clear. I think the connector problem may be due to the car not be used daily, so possibly a corrosion issue. Just a thought. The very high fuel consumption occurs on all the short journeys, but it's most noticeable when cruising at motorway speeds during occasional long journeys when it's only an indicated average 20mpg instead of the normal 40mpg. There's no way I'd expect that sort of difference due to a cold morning (the coolant gets up to normal temperature as fast as expected).

Are you relying on the OBC reading or have you carried out a check from full tank to full tank?
 
If you disconnect the battery before you disconnect the ECU, then when the power is returned the car can't possibly know anything has been touched can it?
 
DSM10000 said:
Are you relying on the OBC reading or have you carried out a check from full tank to full tank?
Relying on OBC (all 3 display versions). My gut feeling is also that consumption is high most of the time, and there's a different feel to the engine, but that may be just psychological.
 
i-CONICA said:
If you disconnect the battery before you disconnect the ECU, then when the power is returned the car can't possibly know anything has been touched can it?
I don't know. I can't be sure that the ECU doesn't have a small internal battery to retain data.
 

Users who are viewing this thread

Back
Top Bottom