I recently had a water pump installed by a so called mechanic, and every since the install y car idle a bit high, and then when i have not started it for awhile it runs rough, like it w ants to shut off. then it will idle up and down as if it was a oxygen sensor issue. Engine light came on and said "Engine Malfunction please drive moderately" Then it went away once it got warm, but whenever I sit at light and car is idling the car idle up and down. I think he may have unplugged something to get to water pump and didn't plug it back up and he broke two hoses coming from manifold and replaced them with rubber hoses could that be the reason?
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2003 BMW 745Li Question: car runs awful when cold
Answer #1patrick mannion from Greg Solow's Engine Room, June 16, 2011, 03:16Master
The plastic coolant hoses on those BMW do get brittle with use/over time and break, it may be best they broke while he was working on the water pump as it may have been a sign they were about to fail and leave you stranded somewhere. I would look for a vacuum hose on the intake manifold or hose from the air filter housing to intake that is loose, ripped or not sealing correctly. Also best to retrieve codes stored in the computer of your car to see exactly what the computer in your car sees as being a problem. Computer may indicate a misfire due to a lean mixture of indicate which sensor is damaged or not operating correctly.
Replybigmyyke, June 16, 2011, 11:28Rookie
Thank you very much Patrick for responding I really appreciate that. Yo are right I think the hose he put on aren't fitting correctly and I did use a OBDII and the code was P0363 which said something about misfire, and gas shut off something to that effect. I will change out those hoses with BMW type hoses and see what happens. I will post later. THANKS PATRICK