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Matt
Matt, Engineer
Category: Cadillac
Satisfied Customers: 20614
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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Cadillac Escalade: 05 escalade , rough idle , would sometimes

Customer Question

05 escalade , rough idle , would sometimes die at a light or when turning . replaced the throttle body . while trying to relearn the throttle body to the computer . I unplugged the battery . Reconnected the battery , drove the truck about 2 miles . While returning home in mid turn the truck stalled on me, now it wont start. What could be the problem . no codes are being givien.
Submitted: 7 months ago.
Category: Cadillac
Expert:  Matt replied 7 months ago.
Hello this sounds like a lack of fuel and could be a lack of fuel pressure from the electrical pump at the tank. If the connections to the pump are corroded or damaged then the pump could stop at any time or could notbe running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,Ideally measure the pressure at the injector rail and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.
Customer: replied 7 months ago.
Checked fuel pressure. Which was good. I'm guessing that crankshaft position sensor.. but I feel I may have activated my anti theft passlock feature ... which is why it's not running. Even with starter fluid
Expert:  Matt replied 7 months ago.
Hello thanks for the infoa failed crank sensor will prevent the engine from starting but usually it also flags up an error code ?very rarely it won't flag a code but still be faulty if you've activated the security system then the engine would not crank over on the starter?
Customer: replied 7 months ago.
Put on a new crank sensor . Nothing.. still won't start. Going to check fuel pressure next... I'm at a lost now.. confused and frustrated.
Expert:  Matt replied 7 months ago.
Hello if the fuel pressure is OK then next check for spark by removing one of the spark plugs and plug it back into its lead and rest it on the metal of the engine ( DO NOT hold it on place by hand) then have your assistant turn the engine over whilst you watch the plug. It should give a fat blue spark at regular intervals. If not then check that there's power to the coil pack (at the other end of the plug lead) using a meter. If there’s 12V at the pack but no spark then check the ECU power supply (fuse and relay) and also the connections to the crankshaft speed sensor. If there is a spark and its still not starting then its likely that the ECU isn't opening the fuel injectors, if the injectors are working you can hear them click - its difficult to hear them with background noise so use a long screwdriver like a stethoscope, placing the handle end in your ear and the metal tip against the body of the injector whilst your assistant turns the engine over.If you can't hear anything check the ECU power is present by measuring voltage at the fusebox and on its relay socket if OK then check the connections to the crank speed sensor and consider replacing this sensor if the wiring / connections look OK If the car will start using a squirt of quick/ easi start into the intake then this confirms the problem is lack of fuel
Customer: replied 7 months ago.
Ok . Sounds like I still have some fishing to do. I will keep you posted
Expert:  Matt replied 7 months ago.
understoodjust get back to me on this post
Customer: replied 7 months ago.
Will do . Because this seems to be a problem. The stalling. . But no start is very unusual
Customer: replied 7 months ago.
Went outside . Truck started fine . Turned it off . It started again . But it cut off moments laters. Turned it again . Started fine . Truck is running . Let's see how long this last. To nervous to drive anywhere. Not reliable yet..
Customer: replied 7 months ago.
Not sure what happened here
Expert:  Matt replied 7 months ago.
Hello OK sounds like there's a poor connection or major sensor thats being effected by the heat, so when its cold its all making contact and working and then failing as its expands with temperature
Customer: replied 7 months ago.
Truck is still stalling out. Checked for loose wires and connectors. Couldn't find anything. Unplugged my negative ground to my battery to reset my pcm. Still nothing. Took it to a shop to today, asked if they would replace my pcm. Of course they want run a diagnosis first. Let's see what they find . No codes are showing. So fingers crossed..
Expert:  Matt replied 7 months ago.
understoodjust get back to me on this post
Customer: replied 7 months ago.
Sure will we'll see what happens. . This is a issue and it must be shared.!!
Expert:  Matt replied 7 months ago.
Hido you still need help?Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you