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From: Ashton Crusher on 20 Mar 2010 04:58 92 Ford Explorer 4.0L OHV V6 130K miles, 10K on double plat plugs, nearly new plug wires. O2 sensor was replaced about 40K ago Sometimes Runs rough when first started. Not just first start of the day, but even when warmed up and then shut down for 15 minutes it will often run rough initially like one cylinder is missing. Roughness usually goes away after it's warmed up but lately it's started to have a bucking/missing/popping under light acceleration. Giving it more gas usually smooth's it out. It will run on up to redline and shift into the next gear and has no problem running up to 90 mph. So unlike what I think of as the typical 'worn out plug" misfire that shows up at high rpm and high load, this show up at medium rpm light to medium load. It has not turned on the check engine light Any ideas? Things I'm thinking it might be.. water in gas bad gas bad injector(s) bad coil
From: PeterD on 20 Mar 2010 09:03 On Sat, 20 Mar 2010 01:58:58 -0700, Ashton Crusher <demi(a)moore.net> wrote: >92 Ford Explorer 4.0L OHV V6 130K miles, 10K on double plat plugs, >nearly new plug wires. O2 sensor was replaced about 40K ago > >Sometimes Runs rough when first started. Not just first start of the >day, but even when warmed up and then shut down for 15 minutes it will >often run rough initially like one cylinder is missing. > >Roughness usually goes away after it's warmed up but lately it's >started to have a bucking/missing/popping under light acceleration. >Giving it more gas usually smooth's it out. It will run on up to >redline and shift into the next gear and has no problem running up to >90 mph. So unlike what I think of as the typical 'worn out plug" >misfire that shows up at high rpm and high load, this show up at >medium rpm light to medium load. > >It has not turned on the check engine light > >Any ideas? > >Things I'm thinking it might be.. > >water in gas >bad gas >bad injector(s) >bad coil You've replaced the cap/rotor? One real possibility is moisture in/on the cap/rotor causing a mis-fire, when the engine warms the moisture evaporates, then re-condenses when the engine cools. (OK, I hope this engine does have a cap/rotor!)
From: Scott Dorsey on 20 Mar 2010 09:11 Ashton Crusher <demi(a)moore.net> wrote: >Sometimes Runs rough when first started. Not just first start of the >day, but even when warmed up and then shut down for 15 minutes it will >often run rough initially like one cylinder is missing. > >Roughness usually goes away after it's warmed up but lately it's >started to have a bucking/missing/popping under light acceleration. >Giving it more gas usually smooth's it out. It will run on up to >redline and shift into the next gear and has no problem running up to >90 mph. So unlike what I think of as the typical 'worn out plug" >misfire that shows up at high rpm and high load, this show up at >medium rpm light to medium load. Check the fuel pressure regulator. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis."
From: willy on 20 Mar 2010 09:12 On Mar 20, 9:03 am, PeterD <pet...(a)hipson.net> wrote: > You've replaced the cap/rotor? One real possibility is moisture in/on > the cap/rotor causing a mis-fire, when the engine warms the moisture > evaporates, then re-condenses when the engine cools. > > (OK, I hope this engine does have a cap/rotor!)- Hide quoted text - > > - Show quoted text - It isn't, "the moisture evaporates, then re-condenses when the engine cools." These are noted for vacumm leaks at the plentum, blown head gaskets and fuel pressure problems. All of which will cause your symptoms. You need to diagnosis it, instead of guessing.
From: willy on 20 Mar 2010 11:23
On Mar 20, 10:56 am, lugnut <lug...(a)roadkill.net> wrote: > On Sat, 20 Mar 2010 01:58:58 -0700, Ashton Crusher > > > > > > <d...(a)moore.net> wrote: > >92 Ford Explorer 4.0L OHV V6 130K miles, 10K on double plat plugs, > >nearly new plug wires. O2 sensor was replaced about 40K ago > > >Sometimes Runs rough when first started. Not just first start of the > >day, but even when warmed up and then shut down for 15 minutes it will > >often run rough initially like one cylinder is missing. > > >Roughness usually goes away after it's warmed up but lately it's > >started to have a bucking/missing/popping under light acceleration. > >Giving it more gas usually smooth's it out. It will run on up to > >redline and shift into the next gear and has no problem running up to > >90 mph. So unlike what I think of as the typical 'worn out plug" > >misfire that shows up at high rpm and high load, this show up at > >medium rpm light to medium load. > > >It has not turned on the check engine light > > >Any ideas? > > >Things I'm thinking it might be.. > > >water in gas > >bad gas > >bad injector(s) > >bad coil > > I think I would go with Scott's tip. If the Fuel PR is > leaking, it may flood one or two cylinders while the engine > is dead. It may take a few seconds to clears the plugs when > restarted. IF the vacuum line has fuel in it, that would be > an indicator of failure. > > Be sure to check around the coil secondary tower for loose > or dirty connection, coil wire failure, etc. Another > consideration is the ignition control module. > > Lastly, do not start to just throw parts at it. If you do > not find fuel in th FPR vacuum line, get the fault codes > read along with the exact text from the screen. Post them > bac here and someone is likely to be able to give you some > decent advice (as well as some total bullshit). > > Lugnut- Hide quoted text - > > - Show quoted text - He said it doesn't turn the light on, so there isn't going to be fault codes. |