2005 Jimmy 4X4, 4.3L, P300 multiple misfire. Have had on scanner, misfires Cylinders 1 and 4. Have changed: both spark plugs and wires, coil and coil lead, distributor cap and fuel filter. Engine does not miss or show any signs of any problem until I exceed 55 MPH (93 KM/Hr)then within 1 mile engine light comes on and shows multiple misfires. Can drive hundreds of miles with engine light off until I exceed 55 MPH.

Question 1

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Po306code?

Misfire in cylinder #6. Could be bad spark plug, spark plug wire, cop coil, bad intake/exhaust valve, clogged fuel injector or piston/cylinder problem. What's the year, make, model, engine and have you been following the recommended maintenance schedule for new plugs?

Oct 12, 2017 • Cars & Trucks

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"I have a 2006 Nissan Pathfinder 4.0 V6... Had ECU replaced . Now is throwing a random misfire code P300... what are these code and can one cause the other? Help!"

code p300 refers to random/multiple misfires--misfire detected==causes--spark plugs--HT leads --injectors--ignition coils--low compression--wiring
If you are only now experiencing the problem after changing the ECU, I would suspect that wiring and connections to the new ECU may not have been fitted properly. There may be problems in the ECU CPU (chip) and it may be necessary to use a scanner to reset the CPU program to recognize the sensors of the vehicle correctly

Nov 22, 2014 • 2006 Nissan Pathfinder

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Misfire on #4 cylinder when accerating on a 2005 renderous

I would start with switching a coil, swap # 4 coil to another spot and see if the misfire moves, the coils on this van operate to cylinders so move it and see if the misfire changes then you know its the coil and if it does not then next thing is to check spark plug and wire, replace the plug and wire and if that solves it then tune up van, good day,

Oct 14, 2012 • 2005 Buick Rendezvous

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My 2005 STS has given me a code that translates to multiple misfires. Any ideas?

A po300 means you have several cylinders misfireing ! Depending on mileage it could just need new plugs ! If you try new plugs only use delco plugs in that vehicle ; it will save you a lot of problems later down the road !

Mar 15, 2011 • 2005 Cadillac STS

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2005 Grand Cherokee 4.7L. When started multiple misfires cyl 1,3,5,7. After running about 1 minute, misfires disappear. Code p0300, sometime accompanied by p0303

P0300 is Multiple Misfire and P0303 is one specific misfire in the cyl #3.

A code P0303 may mean that one or more of the following has happened:
* Faulty spark plug or wire
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector
* Burned exhaust valve
* Faulty catalytic converter(s)
* Running out of fuel
* Poor compression
* Defective computer

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.

Hope helps.

Mar 07, 2011 • Jeep Grand Cherokee Cars & Trucks

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2005 Cavalier misfiring on 2 cylinders, dumping fuel

Spark plugs get there voltage from the ignition coil packs, more then likely you have a bad coil pack or coil pack boot, pull one coil pack or spark plug wire or boot at a time, if you see a drop in rpm, that one is good, if no drop bad coil pack.

Jul 19, 2010 • Chevrolet Cavalier Cars & Trucks

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P300 engine code replaced coil,wire,control module runs somewhat better but still has a steady miss and back fires on acceleration or under a load 1998 chevrolet k1500 z71

did you replace all the plug wires and spark plugs if not that may be your problem did not understand if you did or not from your post

Apr 04, 2010 • 1998 Chevrolet K1500

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Just got 2002 chevy cavalier ls check engine light on code is p300 multiple cylinders misfire, changed plugs and wires now says cylinder 2 misfire what do i do

RECHECK#2 SPARKPLUG, PULL IT OUT AND INSPECT THE GAP TO MAKE SURE IT'S NOT BENT SHUT, IF PLUG IS OK MAKE SURE WIRE BOOT IS ON SECURELY, IF THATS OK THEN SUSPECT A FAULT COIL.

Mar 29, 2010 • 2002 Chevrolet Cavalier Coupe

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Hi, I have a 1997 Porsche 993. Motronic 5.2 M07. I am getting these fault codes 1) 62 misfire emissions-relvant 2) 51 Cylinder 2 misfire emissions-relevant) 3) 54 Cylinder 5 misfire ...

misfire :-------- try checking your 02 sensors /fuel pump and filter.

for 51 cylinder misfire :---
Change the coil. Period. Very easy to remove from the vehicle if it's a 4 cyl. Follow that spark plug wire from the spark plug to the other end. What it's attached to you should replace
for 54 cylinder 5 misfire :---First you have to eliminate the most obvious problems, like spark plug and spark plug wire. If you replace those and you still have a misfire, then it's a good idea to look for a vacuum leak in the intake manifold

Mar 07, 2009 • Porsche 911 Cars & Trucks

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1998 Cavalier No Spark in cylinders 1 & 4

ignition mod. grounds,pcm or timing belt could all be it but, I would have to look at timing first.

Jan 13, 2009 • 1998 Chevrolet Cavalier

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Try some injector cleaner in the fuel--there might be some water in the fuel also. Check the air cleaner.

1 more comment
Anonymous Aug 01, 2009

You need to monitor fuel pressure during driving above 55 MPH. If it drops, look for weak fuel pump or plugged sock filter inside the tank. Will this problem show up just running the engine at a good clip? Any failing sensors should show on the computer scan. Does the problem go away if you slow down below 55? Does the distributor use a magnetic trigger to fire the plugs?
Anonymous Aug 01, 2009

You didn't say whether the engine, by itself, will display the faults if running at 55 MPH-RPM (no load). Is there any connection between the speedometer and the computer as in cruise control? Check for slop in the distributor shaft upper bearing. How did the problem show up--gradually over time, suddenly, always there, after some repair? If the problem only shows on the road, try disconnecting the speedometer at the transmission.
Psastocks Aug 26, 2010

I have the same problem, issue started after repair and replacement of the engine. Old engine did not have the problem. Engine runs fine no sign of misfire, soon as I exceed 110km/h the engine light comes on, code is multiple misfires.

The new engine and work is still under warranty, but I am wondering what the problem can be. The mechanic has changed the dist cap and the new engine only had 45000 kms

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Po306code?

"I have a 2006 Nissan Pathfinder 4.0 V6... Had ECU replaced . Now is throwing a random misfire code P300... what are these code and can one cause the other? Help!"

Misfire on #4 cylinder when accerating on a 2005 renderous

My 2005 STS has given me a code that translates to multiple misfires. Any ideas?

2005 Grand Cherokee 4.7L. When started multiple misfires cyl 1,3,5,7. After running about 1 minute, misfires disappear. Code p0300, sometime accompanied by p0303

2005 Cavalier misfiring on 2 cylinders, dumping fuel

P300 engine code replaced coil,wire,control module runs somewhat better but still has a steady miss and back fires on acceleration or under a load 1998 chevrolet k1500 z71

Just got 2002 chevy cavalier ls check engine light on code is p300 multiple cylinders misfire, changed plugs and wires now says cylinder 2 misfire what do i do

Hi, I have a 1997 Porsche 993. Motronic 5.2 M07. I am getting these fault codes 1) 62 misfire emissions-relvant 2) 51 Cylinder 2 misfire emissions-relevant) 3) 54 Cylinder 5 misfire ...

1998 Cavalier No Spark in cylinders 1 & 4

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Related Questions:

Po306code?

"I have a 2006 Nissan Pathfinder 4.0 V6... Had ECU replaced . Now is throwing a random misfire code P300... what are these code and can one cause the other? Help!"

Misfire on #4 cylinder when accerating on a 2005 renderous

My 2005 STS has given me a code that translates to multiple misfires. Any ideas?

2005 Grand Cherokee 4.7L. When started multiple misfires cyl 1,3,5,7. After running about 1 minute, misfires disappear. Code p0300, sometime accompanied by p0303

2005 Cavalier misfiring on 2 cylinders, dumping fuel

P300 engine code replaced coil,wire,control module runs somewhat better but still has a steady miss and back fires on acceleration or under a load 1998 chevrolet k1500 z71

Just got 2002 chevy cavalier ls check engine light on code is p300 multiple cylinders misfire, changed plugs and wires now says cylinder 2 misfire what do i do

Hi, I have a 1997 Porsche 993. Motronic 5.2 M07. I am getting these fault codes 1) 62 misfire emissions-relvant 2) 51 Cylinder 2 misfire emissions-relevant) 3) 54 Cylinder 5 misfire ...

1998 Cavalier No Spark in cylinders 1 & 4

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