Code 300: Random misfire

Code 300: Random misfire

Postby longyard [OP] » May 15th 2011, 12:44am

Anyone know the most likely cause for this issue? Just showed up today.
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Re: Code 300: Random misfire

Postby Phantom » May 15th 2011, 3:20am

Distributor cap is what I hear that is most common , the short design limits ventilation , make sure you get a high quality cap and rotor preferably with brass terminals and there are vents in the distributor housing that have screens that get plugged up and need to be removed but there are other causes as well
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Re: Code 300: Random misfire

Postby NY Safari TONKA » May 15th 2011, 5:01am

What was the last things done to the van?... :shrug:
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Re: Code 300: Random misfire

Postby longyard [OP] » May 15th 2011, 5:45am

NY Safari TONKA wrote:What was the last things done to the van?... :shrug:


Just completed:
1. power steering pump
2. Water pump
3. Fuel pump
4. All new fuel lines
5. New harmonic balancer
6. New radiator
7. Upgraded alternator to 200amp
8. New idler and tensioner pulleys
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Re: Code 300: Random misfire

Postby longyard [OP] » May 15th 2011, 5:48am

longyard wrote:
NY Safari TONKA wrote:What was the last things done to the van?... :shrug:


Just completed:
1. power steering pump
2. Water pump
3. Fuel pump
4. All new fuel lines
5. New harmonic balancer
6. New radiator
7. Upgraded alternator to 200amp
8. New idler and tensioner pulleys



Oh... and I upgraded the sparkplugs to NGK irridiums. I've driven the van very little, and so am not very familiar with it. Really today is the first drive I've taken in it since I drove it home two months ago (100 mile trip, no issues.) I should note that it was very humid, and sometimes rainy, today, which lends credence to the distributor cap theory.
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Re: Code 300: Random misfire

Postby gillbates » May 17th 2011, 3:44am

I had the same problem whenever it rained. Changed the cap and rotor but it still kept refusing to start in wet conditions. One day when it wouldn't start I pulled the dog house and cranked it. I heard an electrical clicking. When I looked at the engine while cranking it I could see a little lightning bolt shooting across the top of the coil. I replaced that and was good to go. I'm not saying you need a new coil, but I think it would be worth it to pull the cover and crank it on a day when it won't start.
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Re: Code 300: Random misfire

Postby longyard [OP] » May 17th 2011, 4:08am

gillbates wrote:I had the same problem whenever it rained. Changed the cap and rotor but it still kept refusing to start in wet conditions. One day when it wouldn't start I pulled the dog house and cranked it. I heard an electrical clicking. When I looked at the engine while cranking it I could see a little lightning bolt shooting across the top of the coil. I replaced that and was good to go. I'm not saying you need a new coil, but I think it would be worth it to pull the cover and crank it on a day when it won't start.


Thanks Gill. I'm going to get a new coil to add to the new distributor cap I bought. Is it hard to change the coil? Thanks. Bill
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Re: Code 300: Random misfire

Postby Leeann_93 » May 17th 2011, 4:14am

Nope, easy-peasy.
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Re: Code 300: Random misfire

Postby longyard [OP] » May 17th 2011, 5:28am

Leeann_93 wrote:Nope, easy-peasy.


Sounds like I know what I'm doing this weekend!
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Re: Code 300: Random misfire

Postby NY Safari TONKA » May 17th 2011, 6:46am

Ok look here make sure your timing its god chk complete w/Tach....if problem still CHECK YOUR CRANK SENSOR :wave: ...Let us know how it goes....You can chk the voltage on the sensor (at connector Pink or Lt Green wire) w/key ON car off should have about 11.5 Vlt...if any chk blown fuse + wires...
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Re: Code 300: Random misfire

Postby longyard [OP] » May 17th 2011, 12:25pm

NY Safari TONKA wrote:Ok look here make sure your timing its god chk complete w/Tach....if problem still CHECK YOUR CRANK SENSOR :wave: ...Let us know how it goes....You can chk the voltage on the sensor (at connector Pink or Lt Green wire) w/key ON car off should have about 11.5 Vlt...if any chk blown fuse + wires...


Okay. Can you tell me if timing the beast is as simple as lining up the marks on the timing cover and the crank balancer? Those are the only marks I see.
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Re: Code 300: Random misfire

Postby gillbates » May 17th 2011, 11:41pm

I don't think there's much you can do with the timing on an 01 as the distributer only goes in one way. It's not like the good old days when you could loosen it and move it back and forth. Damn computers.

If you do change the coil, and you still have the original, you have to drill out the rivets that connect it to the brace. The new one will come with bolts and nuts. But like I said before, while that was my issue it might not be yours. But pulling the cover and cranking it while it's in non-start mode may (or may not) help you find out.
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Re: Code 300: Random misfire

Postby NY Safari TONKA » May 18th 2011, 5:08am

Can you put up a pic (distributor area) to see for sure what systm you have if EDI (no timing)...if HEI (timing)...I blv after 1995 was the EDI...the misfire it signal by the Hall Effect
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Re: Code 300: Random misfire

Postby longyard [OP] » May 18th 2011, 5:43am

NY Safari TONKA wrote:Can you put up a pic (distributor area) to see for sure what systm you have if EDI (no timing)...if HEI (timing)...I blv after 1995 was the EDI...the misfire it signal by the Hall Effect



I've got a 2001 and the distributor doesn't look like any HEI I've dealt with before. I don't mind replacing parts on a vehicle that's got all it's original stuff after 130K and long exposure to salt on the roads from upstate NY. (I'm down here in NC.)
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Re: Code 300: Random misfire

Postby rev_les » May 19th 2011, 2:46am

The timing is non-adjustable. One other area to look at is the distributor gear itself, these motors are notorious for eating up distributor gears.( I have 3 of these vans, and I've had to replace the gear on 2 so far). If you see ANY groove worn in it, replace it.
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Re: Code 300: Random misfire

Postby NY Safari TONKA » May 19th 2011, 5:38am

Ok Im looking back at what you have change vs old school mech.... :doh: ...when you get a code P030x its at one of the cyldrs...but a P0300 its on ALL... :?: ...What moves in all cyldrs?...SO THATS THE ANSWER FOR YOUR PROBLEM ... :screaming: ....ANYONE!!! for a VICTORY BANANA DANCE :banana:
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Re: Code 300: Random misfire

Postby NY Safari TONKA » May 21st 2011, 4:50pm

:banghead: ...DON'T...Parts to chk for this problem = Vac Leak...Your Fuel Pump or Your EGR..IF After AFTER MAKING A 100% SURE ALL ARE WORKING if problem still let us know

:banana: ...Remember code P0300 its at ALL CYLDRS = FUEL/AIR MIX :banana:
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Re: Code 300: Random misfire

Postby rev_les » May 22nd 2011, 6:33am

...........There are numerous causes of a P0300. It's more than likely ignition related. :2:
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Re: Code 300: Random misfire

Postby NY Safari TONKA » May 22nd 2011, 6:17pm

Would you say, when it is ignition related its P0300x (x=cylndr #) ... :confused: ...But when its P0300 (code comes by itself not with other P0300x) ITS A RANDOM MISFIRE....Bcs its MISFIRE thats where people say it ignition related :think:

All IN A CAR THAT WONT START ITS IGNITION RELATED :rofl: =NO IGNITION NO BOOM! :eek:
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Re: Code 300: Random misfire

Postby rev_les » May 23rd 2011, 5:00am

It can be fuel related, but more often than not, it's ignition related. Go buy yourself a factory service manual. If the engine runs and the fuel pump is not up to correct pressure, one symptom people usually mis-diagnose is that they have a transmission problem. This ISN'T your dads Oldsmobile.
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