2004 Cadillac Deville Logo
Posted on Aug 21, 2009
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2004 caddy deville customer changed plugs,coils,fuel pump and check engine light still comes on for a random misfire,coolant temp sensor and lean condition bank one

  • Anonymous Mar 29, 2014

    CHECK COOLIANT LIGHT COME ON

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pwetherhill

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  • Posted on Aug 21, 2009
pwetherhill
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Change coolant temp sensor. it will be reporting wrong leading to the misfire.

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2007 saturn aura xr code P0300

Check Engine Light On, P0300 Random Misfire Code. A random misfire means your engine is misfiring, but that the problem is not isolated to one or two cylinders. It is jumping around in a random way from one cylinder to another. A random misfire code usually means the air/fuel mixture is running lean. Replace plugs wires and coil packs.Check crank /camshaft position sensors, check MAFS
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How to check coil packs and spark plugs wire with a multimeter. ..having random/ multiple misfire P0300...need to know their spec? 97 Cadillac Deville, 4.6 engine/Northstar

I don't think you really understand what this fault code means, it means that likely all the engine cylinders are misfiring at random no set pattern, not any particular cylinder. I would start with checking for engine vacuum leaks like the intake manifold gasket. that is all I can say since you provided no make, model or year and engine type and size information.
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2002 buick Lasabrea custom service engine soon light code revi ew says multiple misfire detected

Multiple misfires can be caused by a few different things , intake manifold vacuum leaks , low fuel pressure , basic things like plug wires an spark plugs needing to be changed if hasn't been done already . How many miles on the vehicle ? If over 100,000 K timing chain an gear wear can also cause this . The powertrain control module (PCM) uses information from the ignition control (IC) module and the camshaft position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring the variations in the crankshaft rotation speed for each cylinder the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause the three-way catalytic converter to overheat under certain conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for 3-way catalytic converter overheating are present.
If the misfire is random, check for the following conditions:
?€¢
System grounds


Ensure all connections are clean and properly tightened.


?€¢
Mass air flow sensor


A mass air flow (MAF) sensor output that causes the PCM to sense a lower than normal air flow will cause a lean condition. Try operating the vehicle within the Failure Records conditions with the MAF sensor disconnected. If the lean or misfiring condition is not present with the MAF sensor disconnected, replace the Mass Airflow Sensor Replacement .


?€¢
Damaged accessory drive belt or driven accessory


A damaged serpentine belt or belt driven accessory can cause engine load variations sufficient to set a misfire DTC.


?€¢
Air induction system


Vacuum leaks that cause intake air to bypass the MAF sensor will cause a lean condition. Check for disconnected or damaged vacuum hoses, incorrectly installed or malfunctioning crankcase ventilation valve, or for vacuum leaks at the throttle body, exhaust gas recirculation (EGR) valve, and intake manifold mounting surfaces.


?€¢
Fuel pressure


Perform a fuel system pressure test. A malfunctioning fuel pump, a plugged filter, or a malfunctioning fuel system pressure regulator will contribute to a lean condition. Refer to Fuel System Diagnosis .


?€¢
Fuel injectors


Refer to Fuel Injector Solenoid Coil Test .


?€¢
Water contamination in the fuel system can cause a single cylinder to misfire as well as cause a random misfire, refer to Alcohol/Contaminants-in-Fuel Diagnosis .


?€¢
EGR system


Check for leaking valve, adapter, or feed pipes which will contribute to a lean condition or excessive EGR flow.


?€¢
Extended idle


Excessive Open Loop operation caused by extended idling or short trip driving may leave deposits on the heated oxygen sensors. The deposits cause oxygen sensors to respond slowly to exhaust oxygen content, affecting fuel control and causing a misfire to be indicated at idle. This condition is not permanent. To determine if this condition is causing the DTC P0300 to set, review the Freeze Frame/Failure Records for DTC P0300. If the DTC P0300 occurs at high engine speeds, the condition described above did not cause the DTC to set. If the DTC P0300 occurs at idle or very low engine speeds and at engine coolant temperatures below 80?°C (176?°F), the condition described above is very likely the cause of the DTC to set. The deposits on the heated oxygen sensors can be eliminated by operating the vehicle fully warm at mass air flows above 15 g/s.

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98 Pontiac GRAND am

The plugs and crank sensor could have done it, but the TPS and idle air control would have nothing to do with a random miss.
A more likely cause is the ignition module or a fuel problem. You may have to wait until the problem is bad enough to kill the engine or you have more codes to check out.
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Random misfire and O2 Sensor

One major problem with mechanics today is they don't test anything, just replace parts.
The O2 sensor codes do not tell you to replace, only to check. Either the sensors are telling the computer the fuel mixture is too rich, too lean, or not changing at all.
I would have someone check base fuel pressure and volume next. You could be low on fuel pressure or the fuel system may be weak enough to be too lean under some conditions.
The coils could be arcing if the mixture is too lean, electricity takes the shortest path to ground. If the mixture is lean the plugs may be too tough for the electricity to get to ground.
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I HAVE A P0300 OBD CODE I DID A COMPRESSION TEST TO ENGINE AND IT PASS THE TEST,I DID CHECK EGR VALVE,CHANGE SPARK PLUGS,IGNITION WIRES, CAP AND ROTOR, I DID CHECK TPS SENSOR MAF SENSOR,FUEL PRESSURE,AND...

p 0300 code is for random misfires
random misfires are more from dirty /faulty injectors or low fuel pressure than anything else
have a pressure test done to check pressure regulator , filter and pump operation
use a can of quality injector cleaner or remove and clean the injectors
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I have a 95 camaro with a 3.8l. It had a #1 cylinder missfire code, I found out it had a bad fuel injuector so i replaced it. Now, it's showing a random misfire code. What could cause this change

An intake vacuum leak can cause this as well as other issues, read about it below.
Check Engine Light On, P0300 Random Misfire Code A random misfire means your engine is misfiring, but that the problem is not isolated to one or two cylinders. It is jumping around in a random way from one cylinder to another. A random misfire code usually means the air/fuel mixture is running lean. But the cause might be anything from a hard-to-find vacuum leak to dirty fuel injectors, low fuel pressure, a weak ignition coil, bad plug wires, or compression problems. Even a dirty MAF sensor can cause a lean code and/or misfire to occur. The engine may be stalling because it isn't getting enough throttle opening. The cause is often a problem in the idle air control system. The first thing to check is the intake vacuum with a vacuum gauge. On most vehicles a normal reading is 17 to 21 inches Hg. If the needle is lower, is jumping up and down or steadily dropping, you have a vacuum problem. Look for possible vacuum leaks by checking vacuum hose connections, the throttle body and manifold, and PVC valve and plumbing. An EGR valve that is leaking can also act like a vacuum leak and cause a random misfire. The next thing you should check is the fuel pressure with a gauge. If it is not within specifications (refer to a service manual for specifics because fuel pressure is critical for proper engine performance), the problem may be a weak fuel pump, low voltage to the pump (check the relay and wiring), or obstructions in the fuel line (like a plugged filter). A bad fuel pressure relay can also leak pressure and prevent an otherwise good fuel pump from delivering full pressure to the injectors. Dirty injectors can also restrict fuel delivery and cause a lean fuel condition. Many regular grades of gasoline do not contain adequate levels of detergent to keep the injectors clean. Frequent short trip driving accelerates the buildup of injector deposits. Cleaning the injectors with a good quality fuel tank additive (or having them professionally cleaned) can solve this problem. Look at short term fuel trim (STFT) and long term fuel trim (LTFT) with your AutoTap Express DIY. If the numbers are high, it tells you the engine is running lean
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2001 dodge grand caravan sport 3 code 3.3 liter flex fuel random cylinder misfire along with 1 2 5 6 cylinder misfires. scan tools are unable to communicate with computer but check engine light will come...

Dirty fuel injectors. Computer will show misfire on the cylinders that are malfunctioning. If injector cleaner in tank won't clean them, pull them all out and have a professional take them apart and cleaned. Each injector has a screen in it that can get plugged up. Think about Bro, all other stuff has been renewed.
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2003 Ford Ranger 4x4 extended cab- diagnostics checked and got these codes- P0171, P0174, P0300, P0316. Can you tell me what they mean?

P0171------ system too lean bank#1
Po174------ system too lean bank#2
For these 2 codes, try cleaning the maf sensor (mass air flow), that is mounted in the big black hose that goes from the air filter housing to the throttle plate, if it is dirty, that will cause those 02 sensors to send a signal to the computor to lean the air fuel mixture. If cleaning it doesn't work, the sensors will probably need changing.
P0300---- Random/multiple cylinder misfire
P0316---- Cylinder misfire at start up---- first 100 revolutions.
On those 2 codes, you have to do some testing to find out why there is a misfire.
Possible causes:
dirty/malfunctioning injectors
weak coil pack
fowling spark plugs/wires
Low fuel pressure
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Check engine light

A multi misfire may mean that one or more of the following has happened:
Faulty spark plug or wires, Faulty coil (pack), Faulty oxygen sensor(s), Faulty fuel injector(s), Stuck/blocked EGR valve / passages, Faulty camshaft position sensor, Defective computer.

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 wire, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the 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.

Good luck and hope this information helps, keep me posted, be glad to help you get the truck running 100% again. Not sure if your running a K&N air filter, and if you are there may be a flim of oil on the MAF sensor that is making you run lean. You may want to spray down the MAF sensor with a can of MAF cleaner. 
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