P0300 random misfire on 98 exploree V8
jerryls
08-12-2005, 07:01 AM
I get a P0300(random misfire code. The engine starts fine and idles fine. While driving it stumbles occasionally. I have about 80K miles. I suspect the plug wires, but they appear to be in pretty good shape. I hate to change them if that is not the problem. Any ideas what else causes this code?
exploded99
08-13-2005, 01:47 AM
Ideas, yes. But you will probably want to hook up to a scanner that can do real time readings.
Coil packs can cause missing, but the PCM will usually identify the cylinders - it won't be random
Plugs and wires would "normally" cause misses on the same cylinders - not randomly across several cylinders which is what the computer sees when it sets random misfire. I would expect this to show up at idle as well. But if its been a long time since you fed it plugs, it can't hurt.
Could be as simple as some water partially plugging your fuel filter or a pretty dirty fuel filter.
Or it could be occasional low fuel pressure from your fuel pump.
Cam position sensors can give that code - they get weak or dirty. Ford has a TSB out on late 90's vehicles about cam position sensors causing missing, etc. etc. And oxygen sensors might be involved. A dirty Maf is pretty common and could cause the problem,
A good real time scanner can look at how your oxygen sensors are performing, as well as a multitude of other readings. Also, there are several settings stored when the p300 code is set that can be analyzed to see what might be causing your problem.
FYI - Bosch makes a pretty decent set of wires for 62 bucks that accept all the little metal heat shields off your original wires. Takes some time to do the wires - they run through some tight spots.
If it were mine, I would probably do the tune up thing- plugs, wires and a fuel filter, as well as clean the MAF and idle air control valve. Run a can of gas dryer thru it, and if it still did it after that I would go ahead and get the diagnostic done.
Oh yeah, I ran a can of BG44K thru my fuel system at 58k, and it really helped out the performance of my V8. Pretty good stuff. $22 a can at NAPA or Advance auto, but it really works.
Good luck!
Coil packs can cause missing, but the PCM will usually identify the cylinders - it won't be random
Plugs and wires would "normally" cause misses on the same cylinders - not randomly across several cylinders which is what the computer sees when it sets random misfire. I would expect this to show up at idle as well. But if its been a long time since you fed it plugs, it can't hurt.
Could be as simple as some water partially plugging your fuel filter or a pretty dirty fuel filter.
Or it could be occasional low fuel pressure from your fuel pump.
Cam position sensors can give that code - they get weak or dirty. Ford has a TSB out on late 90's vehicles about cam position sensors causing missing, etc. etc. And oxygen sensors might be involved. A dirty Maf is pretty common and could cause the problem,
A good real time scanner can look at how your oxygen sensors are performing, as well as a multitude of other readings. Also, there are several settings stored when the p300 code is set that can be analyzed to see what might be causing your problem.
FYI - Bosch makes a pretty decent set of wires for 62 bucks that accept all the little metal heat shields off your original wires. Takes some time to do the wires - they run through some tight spots.
If it were mine, I would probably do the tune up thing- plugs, wires and a fuel filter, as well as clean the MAF and idle air control valve. Run a can of gas dryer thru it, and if it still did it after that I would go ahead and get the diagnostic done.
Oh yeah, I ran a can of BG44K thru my fuel system at 58k, and it really helped out the performance of my V8. Pretty good stuff. $22 a can at NAPA or Advance auto, but it really works.
Good luck!
jerryls
08-21-2007, 02:14 PM
Changed plugs and wires did the trick
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