Mixture Too Rich Starting On Efi

[Guest Tom Lawless]

:boohoo: Hi Guys; I am having a problem with my pinto 2.0L injection engine. When starting from cold the mixture is much, much too rich. I can see flames from the exhaust at times which look like unburnt fuel being ignited in the exhaust with some popping, ocaisional bangs and lots of black smoke. If the engine is allowed to tick over for too long the plugs soot up and have to be changed. When it finally does heat up the mixture appears to correct its self. I suspect that the engine temp sensor or the air temp sensor in the metering valve. Any ideas will be appreciated.

 

Thanks Tom Lawless

[Guest Fred2b]

I am no expert but could it be you have one plug not firing properly? I have had this before now but you can hear it. Sooting up? What about new oils seals on the valve stems? Just a few thoughts.

Regards

Peter

[Guest Tom Lawless]

Hi Peter; The valve stem seals have been replaced and the plugs have also been replaced. The engine is running oa all four cylinders. The engine starts to run properly, quite suddenly when it reaches normal working temperature. This is why I suspect the temperature sensors.

Thanks for reply.

 

Tom Lawless

[Guest Simon cooper]

Hi Tom,

Has this problem just come on or is this first time you have started it since build etc??

First thing would be temp sensor. This is the white one below the inlet manifold in the centre. Other possibles are obviously the associated wiring of the sensor and the ECU earths.

Check the resistance accross the temp sensor when cold. i cannot remember the values off the top of my head but i can find out if you let me know.

Other causes are air flow meter sticking, normaly caused by back fire into the manifold which causes the flap to buckle.

Get back to me if you are still stuck.

Good luck

Simon

[Guest Tom Lawless]

Hi Simon;

Thanks for the reply. The car is not on the road as yet but I run it regularly. My garage is a bog standard one and most of the construction of the car has been done in my drive way so I have to drive it in and out to work on it. I noticed the problem developing over the last few weeks. Today I had to replace the spark plugs to get the car to start properly. The plugs that were firing were sooted up and the ones that were not were wet with petrol. Even when the car is on tick over it drinks petrol.

I think that your suggestion of the engine temperature sensor is a good bet. Once the engine reaches normal working temperature it starts to run normally and the smoke reduces to almost nothing. I have had the air filter off and had a look at the air meetering unit and it looks normal, the flap is moving and the engine almost stalls if the flap is pushed open slightly. There is a temperature sensor in this unit which I will check when I check the other one.

 

Many thanks

 

Tom

[Guest Ant]

Could be your spark timing. If you have a late spark the engine will run, but not very efficiently, and loads of unburnt fuel ends up in the exhaust pipes. Have you checked the timing with a strobe?

 

just a thought.

 

Ant

[Guest Charles B]

I've had similar problems like this before which have been due to fuel pressure to high. It would be worth getting this checked if you can. Check that you have a continuous return of fuel to the tank. I doubt it is the air temp sensor, as this only affects the mixture very slightly, could be the water temp sensor though.