99 honda accord 4cyl, rough/uneven idle, stalled in the past


My v4 99’accord with 152K miles had stalled a few months back.
*the idle was rough/uneven…
*in stop-and-go traffic sometimes when i would hit the gas pedal,
engine would almost skip a beat or two, and sometimes stall…

the car shop changed the ignition switch…
they cleaned out the EGR valve which had plenty of carbon build up.
after cleaning out the EGR valve the idle was much better…

but over time the idle has gotten worse. i fear another stall is around
the corner. any ideas? is the EGR valve bad?

another thing i noticed while test driving in the parking lot,
i stop and start again by applying low but uniform pressure on the gas,
the engine picks up, then drops, and then picks up and drops a few
times before the car finally picks up speed…



Do you have a “check engine” light illuminated? If so, have you had the codes read? It is helpful to post any diagnostic codes here so everyone can help you troubleshoot your problem.


no CEL, no codes…
the one time it stalled, all the lights on the dash came on and went off…
car started fine after the stall…


It could still be the EGR. When you step on the gas, in normal operation it creates a vacuum that signals the EGR to allow exhaust gas into the fuel mixture. It’s done to cool the combustion process in order prevent to much nitrogen containing pollutants to be formed during accelerations. Usually this is disabled if the engine is cold. Does this problem occur even if the engine is cold?

One thing you might ask your mechanic is if he can temporarily disable the EGR to see if it fixes the problem. If so, you know you just need a new EGR (and probably the EGR ports cleaned out of carbon deposits.)

There’s other stuff that could cause this same symptom too. With no diagnostic codes current or pending, if the problem isn’t the EGR, its going to be tougher to diagnose. Anything allowing unmetered air into the intake manifold could produce this symptom; i.e. a brake booster diaphragm split, faulty PCV, etc. Usually that would produce a “lean” code though.

Here’s what I’d do if I had this problem on my Corolla. Besides reading out the codes and a visual inspection of the workings, especially looking for air leaks, I’d replace the EGR and PCV with new ones, and clean out all the ports. I’d clean the throttle body of deposits and make sure the IAC was clean and working correctly. If there was any routine engine maintenance that was due (according to the maintenance schedule) , like new air filter, new fuel filter, new plugs, valve clearance measurements, timing belt, idle rpm setting, etc , I’d do that.


Sounds to me like the IAC needs cleaning.


thanks for the replies…
the stall has happened twice, once at the lights after i had gone about a mile…
another time the engine was not cold…
the car shop will probably want to replace the EGR…
I had the PCV swapped a few months back (engine oil levels kept dropping)…
(what is a “lean” code?)
I am due for timing belt as well…
i’ll post back with more info
thanks again…


This is a “lean” code:



If you didn’t have a check engine light and no codes, why did you ask about the lean code?


car shop says EGR valve is failing open…
gotta replace it…
hope that fixes it.
thanks for all the suggestions!


I thought the only V4 Honda made was for a motorcycle.


Sssssssshhhhhh, don’t burst their bubble. :wink:


Given what you say, your mechanic’s suggestion of replacing the EGR makes good sense to me. Best of luck.


How much oil are you burning? If you’re using excess oil, that could be carboning up the EGR valve. It could also carbon up the plugs. And the valves It could cause all sorts of idle problems.

And if the oil burning is caused by a simply worn out engine, you’ll never get it running right. Has anyone done a compression test?