Just wanna say in advance, sorry for the lengthy post and THANKS for any help. I need some help on this problem. I have an 03 Ody with approx. 104,415 k miles. I noticed this problem occurring only AFTER I had my 100k service done includ. timing belt, water pump, cabin filter, drive belts, thermostat, and various seals. I did multiple searches and found multiple threads saying that it could be the IAC valve, EGR valve, power steering switch behind the right front tire, vacuum leak. etc.
-no CEL or TCS lights on
-only when the van is hot (driving for about 45mins - 1hr) I get a high idle around 1000 - 1500 rpms in stop and go traffic, city driving. Then at times it goes away on its own... intermittent.
-its a pain when its heavy traffic cause Im constantly on the brakes cause the van wants to take off on its own or im pressing the brakes harder then usual.
-slowing down and just before coming to a complete stop, rpms spike to about 1200 and the van lunges forward, then rmps settle to 1000.
-when rpms are high (1500-1800) and im parking, when I turn off the engine, it sounds really really rough when its shutting down.
-when Im accelerating and lay off the gas (no braking) I notice the rpms drop dramatically and spike back up then slowly decline. (is that normal?)
-the needle isnt "hunting" up and down rhythmically
-no signs of engine threatening to stall at stop lights or parking lots
Things Ive done so far...
1st time around (worked for about a week then the symptoms came back)
-cleaned the IAC valve with sea foam and qtips and used new oem gasket (when taking apart I noticed that its magnetic in the black electrical box, does it matter what position the flat platform thats on the butterfly is in when putting the electrical part back on?)
-cleaned EGR valve with new gasket.
-poked or probed the PS wire switch with a stick to see if it made the idle respond (turned out ok)
-cleaned under my valve cover (passages were covered in carbon build up: test drove but it seemed like I lost power)
-air dried with a compressor
2nd time around (again, worked for about a week then the symptoms came back)
-cleaned the IAC valve (this time I used carb + choke cleaner) also, I was able to get the butterfly to rotate a complete 360* both ways. The first time, I felt restriction rotating it so I stopped and rotated the other way then stopped. I had restriction under the "bridge" or that part that I cant get to.
-cleaned EGR valve with carb + choke cleaner
-both air dried with a compressor
3rd time around (worked for a few days)
-checked for broken or frayed wires on the PS switch (none)
-cleaned with electrical contact cleaner
-used di electric grease
a few questions...
-when clean, if my IAC valve is bad, would I still get the same intermittent symptoms or would it be more severe and constant?
-when clean, if my EGR valve is bad, would I still get the same intermittent symptoms or would it be more severe and constant?
Id just hate to spend a few hundred of dollars to do process of elimination when none of them are the problem.
Thanks again for any help, info, advice on this troubling problem that just wont leave me alone.