02 sensors

[gravel]

hi lads im new to the forum ive got a 1998 320 ml 65000 mls, my problem is that when i start the car from cold it runs crap then stalls when the car gets warmer its ok, its not the mass, plugs, leads, coils etc, etc i removed and inspected the 02 sencers, they were a bit coked up but looked ok, i dont want to buy new as this might not be the cure, surley if they were faulty it would run crap when warm? is there anything to else to look for?
ie, is there a cold valve idle sencer? or anything else to look for regarding the choke system?
its not the egr tube blocked, it was clean as a whisle,
ive searched other sites, but im still pulling my hair out.

 

[jaymanek]

you need to get the car on a diagnostic machine... the 02 sensors would cause the engine light to come on...

 

[gravel]

02

its showing no faults, but smells very rich on start up

 

[grober]

its showing no faults, but smells very rich on start up

Probably should smell of petrol initially if its got a cold start valve. Have you checked your engine coolant temperature sensor- the ECU needs to know the engine is cold to compensate the mixture/idle rpms

 

[Dieselman]

Have the O2 sensor readings checked as it sounds like they may be on the way out but not far enough to throw a fault code.

There isn't a cold start valve as such, the fuelling is perfofrmed by the main injectors only.

 

[television]

Have the O2 sensor readings checked as it sounds like they may be on the way out but not far enough to throw a fault code.

There isn't a cold start valve as such, the fuelling is perfofrmed by the main injectors only.

The 02 sensor has little to no effect on cold starting, if this was the case then you would have problems in starting due the the constant weakening effect of the 02 sensor

 

[gravel]

ive heared that also as the 02 sencers are by passed giving a richer fuel on start up, (open loop?) but it does smell to rich thats why its stalling, is there any info on the choke system i should be looking for?

 

[television]

ive heared that also as the 02 sencers are by passed giving a richer fuel on start up, (open loop?) but it does smell to rich thats why its stalling, is there any info on the choke system i should be looking for?

There is no choke it uses fuel enrichment, you could measure the sensors water and temp, they should read around 7.5k ohms cold and quite low ohms when hot, for them to make it rich they would be in excess of 4k when hot

 

[gravel]

Good point, where are the sensors fitted?
sorry for being nieve, as ive been looking down different lines.
is it on the radiater or the block?

 

[grober]

This is for the E320 e class UP TO 99 but probably same engine?? item 29 Not sure of any others usually one for the temperature gauge and one for the ECU http://www.detali.ru/cat/oem_mb2.as...GA=722.607&CT=M&cat=19Y&SID=15&SGR=120&SGN=05

 

[television]

This is for the E320 e class UP TO 99 but probably same engine?? item 29 Not sure of any others usually one for the temperature gauge and one for the ECU http://www.detali.ru/cat/oem_mb2.as...GA=722.607&CT=M&cat=19Y&SID=15&SGR=120&SGN=05

All of these engines do not have air temp sensors of late, but as Grobers link that is the water temp sensor, you can short the wire to ground, that is the leanest setting to test

 

[gravel]

cheers grober

 

[gravel]

02

thanks for the replys lads, is there any other sensors etc which determines the mixture on cold start, ill check the water temp sensor.

 

[television]

I believe that it is done via the MAF as many cars do not have a air temp sensor on its own

 

[gravel]

has anyone got any info on the throtle valve for a 1998 320 ml.

 

[grober]

do you mean item 80 the electronic gas actuator. http://www.detali.ru/cat/oem_mb2.as...GA=722.607&CT=M&cat=19Y&SID=14&SGR=030&SGN=01

 

[gravel]

cheers