Hi Folks....... This is driving me crazy. On a cold start, the idle
surges. You can watch the tach bounce up and down for about 45 to 60
seconds, then the car runs smooth as silk. Some days it does it, other
days ....nothing. The dealer can't fix it unless it's doing it !!!!!!

I've changed the fuel filter...... installed a new idle air control
valve.....ran several bottles of fuel system cleaner through it. It
still intermitently surges. Oh yeah, I also cleaned and checked the MAP
sensor and the Air temp sensor ( all in the same housing). Nothing !!!!

No codes are ever set! Would good is OBD II ?????? I'm wondering.....temporary vacuum leak .... but where ?????

 

A high idle is common with fuel injected cars when it is cold or after an over night sitting. I'm not sure what you mean by surges, but as long as it returns to a smooth idle after abit of time, I would not worry about it. It is perfectly normal on start-ups. The IAC acts like a choke when the air is cold, so naturally it needs more fuel to compensateuntil it reaches anoperating internalair temp that is good for normal combustion to occur.

 

The surging, ( something like lightly tapping up and down on the gas pedal )will actually propel the car slightly if it is in gear. This never occured in the previous 4 yrs. that I have driven the vehicle. Once again I am at the mercy of an intermittent drivabilityproblem.......!!!!!!!! If it would stall, orsurge continually,I could get someone to find what the culprit is.[img]smileys/smiley26.gif[/img]

 

first of all your iac is not a choke 2nd your problem is the upper and lower intake orings they get get hard and when you first start the car they cause avacleak which is unmeterd air causng the iac to try to compensate thoe orings are avaiable at your dealer if you have some tech backround then you can proqably due it yourselfif not have a diffrent dealer due it since they should have fig this out since its a common problem hope this helps let me know also when the eng gets warm the seals soften up thats why the problem dissappears

 

I'm sorry....... but you lost me on the upper and lower O-rings ????

Located where ???? Can these rings heat up to a point of change that
quickly, even they are a little hard,.....we're talking at most 30
seconds, 45 seconds when it's real cold .

 

there located below the intake manifold which is the plenum between the 2 valve covers and yes they will expand and shrink that fast

 

It still feels like a fuel delivery problem to me. What if the fuel system is losing some of its pressure, and rapidly builds it back up within a few seconds of stratup??? This could probably only be found if pressure readings were taken before startup ???

 

I never called the IAC a 2ndchoke WWEB.(What about the first choke?) No chokes, no joke!You may need a valium and a nice nap. Try to analyze the person with the problem and if they are going to understand your jibber jabber or it just confuses them more. Try nice or don't write, even if you are Mr. Know-it-all.