FullSizeBronco.com - 78 - 96 Ford Bronco offroad club, forums, tech, installs

96 FSB · 02-28-2010, 10:21 AM

I dont know if this is related to the six litre tune up or not but I did this tune up a few months ago and lately my engine has been idling rough. Today is the second time it has thrown a p0300 code (multiple cylinder misfires) since I did the tune up and it never did this before. I read another thread that someone had misfiring codes and it was an issue with regular plugs and there problems were fixed going back to the motorcraft. I had removed the original platinum motorcraft plugs and put in cheap autolites and regapped like the 6 litre recommends. not sure what to do now. just figured I'd just wait and see what you guys have to say before I go and spend more money on plugs. oh and also I used the MSD replacement coil in the tune up which I later read some people had some problems with.

**miesk5** · 02-28-2010, 10:56 AM

yo

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

Causes; A code P0300 may mean that one or more of the following has happened:
Faulty spark plugs or wires check each wire for connection integrity first. Ensure that routing is ok;
Look at that VECI Label on top of radiator; look at the spk plug wire routing diagram carefully.
Spark Plug Wire Routing & Firing Order TSB 94-04-10 for 87-93 5.0 & 94-96 5.0 & all 5.8 - engine miss, spark knock, buck/jerk, surge and other driveability concerns
Source: by Ford via Steve83
Test coil before pulling plugs to inspect again and re-gapping to save your time & $ http://www.msdignition.com/page.aspx?id=3206
Re-gap Plugs
Faulty coil
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer (not likely)

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.
by obd-codes.com

**miesk5** · 02-28-2010, 11:03 AM

I added the MSD Coil Test Link

and included doing the EZiest and cheapest DIY testing/inspections first based on probable Causes for da Code

96 FSB · 02-28-2010, 11:42 AM

Hey thanks for the reply. I have already read the code possible causes. the msd coil i am using is just a factory replacement and not that msd-6a box in your link. today Im going to pull the egr and have a look to rule that out. Its not that old either. This seems to be more of a problem when the engine is warming up. once its up to temp it dont seem to be an issue.

**miesk5** · 02-28-2010, 02:45 PM

ok
Do you have the Ford Bronco Electrical and Vacuum Troubleshooting Manual (EVTM), Powertrain Controls and Emission Diagnosis Manual (PCED), Service Manual CD from Steve83 or E Bay?
If not, suggest you get one..best under $20.00 thang you'll ever get to repair the Bronco!

96 FSB · 02-28-2010, 07:04 PM

well I pulled the egr off and it seems to be clean and working just fine. I put it all back and go figure it ran good, atleast for now anyway. tomorrow we'll see what happens when i warm it up again.
Im kinda hoping someone with a 96 that has done the 6 litre tune up would chime in. have you did this 6 litre tune up??
I need to find out how to test the coil output and what it should read.

02-28-2010, 10:21 AM	#1
96 FSB Registered User Join Date: Jun 2006 Location: Babylon Long Island NY Posts: 471 iTrader: (0) Bronco Info: 1996 Bronco Sport pkg lifted 96 FSBs Garage	p0300 code I dont know if this is related to the six litre tune up or not but I did this tune up a few months ago and lately my engine has been idling rough. Today is the second time it has thrown a p0300 code (multiple cylinder misfires) since I did the tune up and it never did this before. I read another thread that someone had misfiring codes and it was an issue with regular plugs and there problems were fixed going back to the motorcraft. I had removed the original platinum motorcraft plugs and put in cheap autolites and regapped like the 6 litre recommends. not sure what to do now. just figured I'd just wait and see what you guys have to say before I go and spend more money on plugs. oh and also I used the MSD replacement coil in the tune up which I later read some people had some problems with. __________________

02-28-2010, 10:56 AM	#2
miesk5 I used to know this stuff Join Date: Oct 2003 Location: USE FORD PARTS, let da ZONE handle ice scrapers Posts: 4,599 iTrader: (1) Bronco Info: 96 XL 5.0 E4OD, Man Xfer/Hubs miesk5s Garage	yo 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 Causes; A code P0300 may mean that one or more of the following has happened: Faulty spark plugs or wires check each wire for connection integrity first. Ensure that routing is ok; Look at that VECI Label on top of radiator; look at the spk plug wire routing diagram carefully. Spark Plug Wire Routing & Firing Order TSB 94-04-10 for 87-93 5.0 & 94-96 5.0 & all 5.8 - engine miss, spark knock, buck/jerk, surge and other driveability concerns Source: by Ford via Steve83 Test coil before pulling plugs to inspect again and re-gapping to save your time & $ http://www.msdignition.com/page.aspx?id=3206 Re-gap Plugs Faulty coil Faulty oxygen sensor(s) Faulty fuel injector(s) Burned exhaust valve Faulty catalytic converter(s) Stuck/blocked EGR valve / passages Faulty camshaft position sensor Defective computer (not likely) 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. by obd-codes.com __________________ See our Big Bronco Technical, Parts Sources & Technical Service Bulletins Links site 96 XL 5.0 E4OD, Man Xfer/Hubs Our SF Site THANKS to ALL WHO SERVE! Last edited by miesk5; 02-28-2010 at 11:02 AM.. Reason: spAllAng

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p0300 code

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02-28-2010, 11:03 AM	#3
miesk5 I used to know this stuff Join Date: Oct 2003 Location: USE FORD PARTS, let da ZONE handle ice scrapers Posts: 4,599 iTrader: (1) Bronco Info: 96 XL 5.0 E4OD, Man Xfer/Hubs miesk5s Garage	I added the MSD Coil Test Link and included doing the EZiest and cheapest DIY testing/inspections first based on probable Causes for da Code

02-28-2010, 11:42 AM	#4
96 FSB Registered User Join Date: Jun 2006 Location: Babylon Long Island NY Posts: 471 iTrader: (0) Bronco Info: 1996 Bronco Sport pkg lifted 96 FSBs Garage	Hey thanks for the reply. I have already read the code possible causes. the msd coil i am using is just a factory replacement and not that msd-6a box in your link. today Im going to pull the egr and have a look to rule that out. Its not that old either. This seems to be more of a problem when the engine is warming up. once its up to temp it dont seem to be an issue.

02-28-2010, 02:45 PM	#5
miesk5 I used to know this stuff Join Date: Oct 2003 Location: USE FORD PARTS, let da ZONE handle ice scrapers Posts: 4,599 iTrader: (1) Bronco Info: 96 XL 5.0 E4OD, Man Xfer/Hubs miesk5s Garage	ok Do you have the Ford Bronco Electrical and Vacuum Troubleshooting Manual (EVTM), Powertrain Controls and Emission Diagnosis Manual (PCED), Service Manual CD from Steve83 or E Bay? If not, suggest you get one..best under $20.00 thang you'll ever get to repair the Bronco!

02-28-2010, 07:04 PM	#6
96 FSB Registered User Join Date: Jun 2006 Location: Babylon Long Island NY Posts: 471 iTrader: (0) Bronco Info: 1996 Bronco Sport pkg lifted 96 FSBs Garage	well I pulled the egr off and it seems to be clean and working just fine. I put it all back and go figure it ran good, atleast for now anyway. tomorrow we'll see what happens when i warm it up again. Im kinda hoping someone with a 96 that has done the 6 litre tune up would chime in. have you did this 6 litre tune up?? I need to find out how to test the coil output and what it should read.