Question about Cars & Trucks
One thing that might cause that is too much back pressure in the exhaust, like a clogged catalytic converter. Try disconnecting the exhaust in front of the converter and see if it starts.
Posted on Oct 21, 2013
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Posted on Jan 02, 2017
SOURCE: buick lesabre nightmare
Need to get a scan tool and look at the data stream while it is running for alot more info.Also any trouble codes.Sounds like initially,the engine isn't getting any fuel.I would have a pressure gauge connected to the fuel rail on the engine,so i could monitor the fuel pressure while all this is going on.Items to look at on the data stream would be timing,what timing is the PCM commanding for the engine.Also,have you checked for continuos power feed to the coils during this no start condition,and fire at the plugs while cranking.You could possibly still have spark,but maybe it is extremely weak?I have seen bad ignition switches cause weird problems before too.Many things power up through the ignition switch,just a thought.Have also seen bad PCM's cause strange problems..38 volts is a little on the low side for GM.Usually see those at,at least .50 and up,and rise steadily while pressing the throttle,up to just under 5.0 volts.Potentiometer with 5 volt supply.Vacuum leak can be checked with engine running at a steady idle speed,spray brake cleaner all around the intake manifold and listen for engine speed change.
Posted on Jul 31, 2008
The upper intake has a egr port right next to a coolant port, the egr is exhaust gas that is recyled into the intake for emission control. On a long trip the exhaust burns a hole between the two ports causing your problem. Pretty common on the 3.8. My suggestion is to stop driving it until you have it repaired, reason being is the coolant can travel down the intake and fill up the cylinders. If that happens, worst case you can damage a rod, but you will be stranded.
Posted on Apr 05, 2010
You might try a crank sensor, most of the time if you pull it out you may see a crack in it. It's between the top of the oil pan an the transmission, good luck.
Posted on Jun 22, 2010
SOURCE: po300 code possible fixes?
Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.
A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.
Symptoms may include:
the engine may be harder to start
the engine may stumble / stumble, and/or hesitate
other symptoms may also be present
A code P0300 may mean that one or more of the following has happened:
Faulty spark plugs or wires
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Possible Solutions: If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.
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Posted on Aug 03, 2012
Testimonial: "thank you for your suggestions.codes were cleared,so far po140 has not returned (bank one,sensor two).code po300 returned in less than five minutes.will check vacuum,hoses,and egr next."
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