99 Accord Has Me Stumped

For almost a year I have been struggling with a recurring problem that appears to be triggered by sustained driving on the highway. It has come up
three times now and I thought I had it fixed after the second episode so I don't know what to try next.
It's a 99 Accord LX 4 door 4 cyl 5-speed, 184,500 miles (lots of highway driving).
The problem is after the engine hits operating temperature, it cannot idle at the bottom end -- when you slow down it just drops off to zero RPMs and dies unless you feed it gas with the clutch down. It first happened during an all-day drive last summer. I had just changed the oil, filter and air filter for the trip. To try to fix it, I replaced the spark plugs and the PCV, ran some injector cleaner through, and replaced the coolant and the ignition coil. That seemed to help a little and the car stopped dying so much but still ran uncertainly at low RPMs. Then I took another long drive (this time a warm day in December) and the same problem came back. This time I switched out the ignition wires, distributor cap and rotor. Lo and behold the car seemed almost back to normal. I have driven it up to 50 miles at a time without incident. But this weekend my son drove over an hour on the highway (warm abient temps, too) and sure enough, it started dying again.
There are no trouble codes being activated. I'm looking for a good idea on what to try next and this group is a great help. Thanks in advance for your suggestions.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I am no expert, but I suggest you look at ignition and fuel (filter, timing, plugs, module). When was the last time you tuned it up?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks, Spam. The fact that it always waits to start dying until heating up suggests to me that something electronic is happening that causes the computer instructions on where to set low idle get interrupted somehow. The ignition, timing and idle all work perfectly fine while the car is warming up. Also, they have been working fine on short trips for the last few months. The problem only re-occured after a longer drive at high speeds.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Maybe you should monitor the reference voltage going to the Throttle Position Sensor(TPS)and the TPS output voltage.Perhaps the ref V is dropping(it's source is the ECU),or the TPS output is changing (bad TPS)and telling the ECU to lower the idle....to a point where it will not run properly. Take a "cold" reading on the reference V,then another when the engine starts to stumble. You'll have to backpin the connector.
Or maybe the igniter (in the distributor)is the problem;perhaps altering the firing of the coil once it warms up.
--
Jim Yanik
jyanik
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks, Jim. Your suggestions sound promising.
Would high or low voltage out of the TPS trigger a trouble code? (I haven't had one with this problem.)
The igniter also sounds like a possible answer, especially given it's closeness to the hottest part of the engine. But replacing it will be a $130 gamble. Is there any way to test the igniter?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
John Smith wrote:

yes. it's written up at tegger.com. but if the vehicle runs at all, it's unlikely to be the igniter.
bottom line, if working on the distributor scratched the itch, and it seems to have, keep poking about with that. suggest removal, cleaning, and thorough inspection. read all of tegger's write-ups on ignition problems.
also, make sure you use denso or ngk plugs.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

--
Jim Yanik
jyanik
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

--
Jim Yanik
jyanik
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jim Yanik wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload


Since the igniter contains an IC to adjust the "dwell" time of the transistor that is the actual power switch,it's possible for that IC to get flaky at a high temp,or even at a narrow temp range.With electronics, "either works or it doesn't" is not always true.
also,doesn't the igniter feed back data to the ECU,thru the tach output?
--
Jim Yanik
jyanik
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jim Yanik wrote:

the added complexity compounds the problem, not mitigates it. ever had computer componentry flake on you? one minute it's there, next it's gone. pow.

no, the ecu relies on the sensors in the distributor for rpm input. if you think about it, the tach line is just a phased version of the ecu's own output - not much good for ecu feedback purposes.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jim Yanik said the following on 6/13/2007 12:01 PM:

Engine) that turned out to be a gummed up throttle body. There were no engine failure lights, the idle speed would just drop to zero.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
John Smith wrote:

[low revs cause vibration which can make the switch contact "noisy". always return the key to the "run" position by hand, don't rely on the string to return it fully. and make sure you have no other heavy objects on the key ring.]
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jim, You're right. I had the recall service done at the time it was announced. Thanks.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    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.