1990 Accord LX Misfire Problem

Hi All!
My 90 LX just developed a misfire problem today and Im hoping someone may have some insight.
1990 Accord LX, 5-Speed, 127k miles.
Im no pro mechanic, but Ive done most of my own work on my cars and
motorcycles for the last 25 years. I definitely know my arse from a 12 point, 3/8" drive, Snap-On Flank Drive, deep socket.
Anyhow, heres the story... I replaced my radiator last week due to a small crack in the top tank. While I was at it, I also replaced the radiator hoses and the thermostat. I was very careful to put everything back in as it was supposed to be and the job turned out ok... no leaks and the car ran fine.
Today, when I was getting off the freeway, (highway, for those of you outside CA) I felt the car misfiring/skipping, like it wasnt running on all 4. It was not a totally constant misfire, through all RPMs and loads. Most noticably, it did it at low to mid RPMs, under medium load. The idle would fluctuate from normal to misfiring. I could get the car to buck pretty good at part throttle, 3rd gear, accellerating moderately. The car started back up ok after making a few stops too. No check engine light.
I already took care of the obvious and changed out the cap, rotor, wires, and plugs, but no luck. All wires and hoses in the areas I worked on were also double checked... everything was connected and tight.
When changing the spark plugs, a couple of them were only finger tight, but no signs of compression burn-by or anything like that. I gapped the new ones at .044", used some copper anti-sieze on them, and torqued them properly. Also possibly worth noting... there was some oil on the plug boots down in the holes and also a little bit in the very bottom of the distributor, but not really enough to worry about.
So, the car continues to misfire.
Is there anything obvious that I may be missing?
What sensors are in the area of the lower/rear radiator hose that I may have knocked into and possibly should re-examine?
Any other thoughts?
TIA! -Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
OK, nevermind... Im a moron.
After figuring out what was the water temp gauge sensor, the water temp for the ecm sensor, and thoroughly checking all the wires and connectors around there, I noticed that with my head close to the valve cover, I could hear a faint clicking sound when the engine was stumbling at idle... plug wire!
I had just replaced the wires about a year ago and probably havent put more than 6k miles on the car since then, so I really thought they were good... good enough to disregard them as the culprit and good enough to say I had changed them ;)
Cylinder 4 plug wire was arcing through the plug boot, down at the plug. I was able to pull the upper part of the boot back and see the pretty light show down in the hole. I put a few wraps of Super 33 electrical tape around the boot, put it back in, and the car runs fine. Ill be buying a new set of wires tomorrow.
I really thought the problem had something directly to do with the radiator swap!
Sometimes the obvious is just not obvious enough.
"Heathen" wrote: > Hi All! > > My '90 LX just developed a misfire problem today and I'm > hoping someone may have some insight. > > 1990 Accord LX, 5-Speed, 127k miles. > > I'm no pro mechanic, but I've done most of my own work on my > cars and motorcycles for the last 25 years. I definitely know > my arse from a 12 point, 3/8" drive, Snap-On Flank Drive, deep > socket. > > Anyhow, here's the story... I replaced my radiator last week > due to a small crack in the top tank. While I was at it, I > also replaced the radiator hoses and the thermostat. I was > very careful to put everything back in as it was supposed to > be and the job turned out ok... no leaks and the car ran fine. > > > Today, when I was getting off the freeway, (highway, for those > of you outside CA) I felt the car misfiring/skipping, like it > wasn't running on all 4. It was not a totally constant > misfire, through all RPMs and loads. Most noticably, it did it > at low to mid RPMs, under medium load. The idle would > fluctuate from normal to misfiring. I could get the car to > buck pretty good at part throttle, 3rd gear, accellerating > moderately. The car started back up ok after making a few > stops too. No check engine light. > > I already took care of the obvious and changed out the cap, > rotor, wires, and plugs, but no luck. All wires and hoses in > the areas I worked on were also double checked... everything > was connected and tight. > > When changing the spark plugs, a couple of them were only > finger tight, but no signs of compression burn-by or anything > like that. I gapped the new ones at .044", used some copper > anti-sieze on them, and torqued them properly. Also possibly > worth noting... there was some oil on the plug boots down in > the holes and also a little bit in the very bottom of the > distributor, but not really enough to worry about. > > So, the car continues to misfire. > > Is there anything obvious that I may be missing? > > What sensors are in the area of the lower/rear radiator hose > that I may have knocked into and possibly should re-examine? > > Any other thoughts? > > > TIA! -Joe
--
Posted at author's request, using http://www.AutoBoardz.com interface
Articles individually verified to usenet standards. Visit URL to contact
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Heathen wrote:

Get either Honda OEM plug wires or NGK. I've had good experiences with both on other models. OEM wires are typically good for about 100K miles. The oil in the distributor suggests that the distributor seal is starting to fail. The seal is not available separately but an inexpensive repair might be to find a decent looking used distributor (you'll probably want to swap over your current ignitor and coil). In addition, the oil in the bottom of the spark plug holes could be a problem if there's enough to get on the new plug wires. Fixing this problem requires you to remove the rocker arm assembly and replace the seal rings between the head and the cam towers. This diagram, http://tinyurl.com/ykhxjv , is for a'90 LX 4 Dr with AT and the part I'm referring to is #19. You should do all four of them and also replace the cam seal and the distributor o-ring as well. You can access a copy of the factory service manual at http://tinyurl.com/ykq4gl (though I wasn't able to locate the section for removing the rocker arms). One of the more prominent tips is to not remove the cam tower bolts from the rocker arm assembly when you remove it from the cylinder head. This keeps the assembly together and prevents mixing up the rocker arms so they stay associated with the same cam lobes. Another tip for success is to use just a bit of ultra grey silicone at the four corners of the rocker arm assembly to ensure that there isn't any oil seepage from between the outer two cam towers and the head.
Eric
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Eric wrote: In addition, the oil in the bottom of

         Take the valve cover off and replace the gasket AND the seals between the cover and the spark plug hole in the head. Leave the rocker arm alone. Parts for the gasket and seals should be together in the valve cover gasket kit.     I agree that silicone sealant should be used at the right angle turns where the valve cover meets the head. You may see where the factory assembly used it when new.     I have seen the oil at the bottom of the spark plug wire cause the miss that you first described. bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Eric wrote:

most unlikely it's that seal - change the "b" seals that come with the rocker cover first - they are the ones that usually leak.

those are the ones.

silicone will stop any leakage, but the best sealant in this application is the non-setting type. it's a stiff plastic paste. personally, i don't bother with sealant and the gaskets hold just fine.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
jim beam wrote:

Thanks for catching my oversight. The upper spark plug tube seals should always be replaced first. Replacing these seals will usually fix the oil leak and the lower seals should not be touched unless the oil leak continues even after replacing the upper spark plug tube seals. The upper tube seals are part #4 in this diagram http://tinyurl.com/y5fz89 and they don't need any ultra grey silicone to seal, just make sure that they sealing surfaces are clean.
Eric
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.