1990 300ce warm running problem

[pugboy]

Can't seem to get to the bottom of this one. Car starts fine and runs evenly with idle at around 600-700 revs for ten mins or so and then starts to run rough, smells petrolly so i assume it's over fueling, and the idle will generally go up to around 1500rpm, but sometimes fluctuating between 600 and 1500. I've been told it may be related to the 'blue plug' on the top side of the engine, I assume this is some sort of temperature sensor.

Any thoughts would be most appreciated.

Cheers

Chris

 

[television]

The cold start valve could be turned/stuck on full, that would cause the engine to run rich and smelly and rough,,these things are controlled by sensors there is an air temp sensor in the intake and the water sensor

 

[pugboy]

Thanks Malcolm

The sensor on the airbox inlet is wobbly but would that effect hot running? Is the water sensor you mention the blue plug? I could try changing thse first if it's a cheap fix.

Where is the cold start valve located?

Chris

 

[television]

By removing the wire from each sensor and shorting it to ground (chassis) this would tell the engine that it is hot and all fuel starting devices would be turned off if they are OK

 

[pugboy]

Sorry to be a pain but presumably it is just a switch so if I pull out the blue plug and just put a wire across the two terminals will that achieve the same?

Thanks

Chris

 

[television]

I do not know what the blue plug is, my reference is to the water temp sensor and the air intake one

 

[Ellsy Tanners]

Check the distrubitor cap and rotor arm, either worn or damp or oilly.

I,d bet you a tenner its your prob!!!

 

[pugboy]

Ellsy

..Put the cheque in the post mate!!

Well you're right and wrong, it was running rubbish and struggling to start prior to this problem after being stood for a few weeks and only having done short journeys for a while. However, I did then remove all the plugs and the dizzy cap and yes, it was very damp. Anyway, after a good clean it fired on the first turn, and then once it got warmed up, then the erratic idle started.

Chris

 

[Ellsy Tanners]

What was the condition of them like, if the get too old and corroded then they can start breaking down when getting warm give poor resistances and running issues.

I am holding on to my cheque for know lol!!!!!!

 

[pugboy]

The dissy cap was replaced about 6 months ago but was pretty damp. The plugs were quite petrolly and black but I dried them off and gave them a bit of a going over with a wire brush. I supect (although maybe wrongly) that my issue is one of fueling somehow as it initially runs well until warm and then gets progressively worse and will even backfire sometimes if the throttle is blipped, which is good if you're down at the local cruise but not really in keeping with a pillarless waftmobile!

 

[television]

Back firing does point to the dizzy cap leaking