X-Type V6 2.5 2006. Strange cold start behaviour developed.

When starting cold, starts immediately, no problem, to 1,000 rpm. After 10 seconds falls right back to around 400 rpm, engine spits, then after a further 10 seconds recovers back to normal 1,000 rpm and is fine for the rest of the day.. If I touch the accelerator in the slow running moment, engine stalls, but restarts fine. Warm start does not happen. Anyone any ideas ?

 

Could be an air leak. As it's when cold and near cold may be awkward trying to watch fuel trims (try, though) but maybe watching the OBD status for OL/CL (open/closed loop) will help - the drop to 400 may be as it tries to go CL. It may even be going CL momentarily then back to OL due to (say) a leak.

 

henry, try cleaning the throttlebody and then see what you have afterwards. You may find this will solve your problem. You want to especially concentrate on the edge of the butterfly disc that is blocking the air flow. This is known to get gum on it from burnt oil and this will cause the butterfly to stick. Of note, use your finger to hold the butterfly open and spray away with a quality throttlebody cleaner (can use carb cleaner if you have it at this point as the protective film that was installed at the factory is long gone by this point). then finish the job using the rag to catch the edges of the butterfly. At this point, the engine is going to be "flooded" from all the cleaner sprayed into the intake. To clear this condition, when you go to start the car, depress the gas pedal down as far as it will go. This is a command to the ECU to not fire the fuel injectors. Keeping the gas pedal fully depressed, attempt to start the car. After about 5 seconds, ease off of the gas pedal and let the motor catch and bring it up to idle.