Hi,

please help me to figure this out. I own 99 Accord EXV6 sedan 60Kmi on it, no engine mods.
I started noticing that while idling my RPM _sometimes_ drops to about 300,and comes back in 2-3 sec. The same now _always_ happens when I switch gears from P to D or especialy from D to Reverse.
A few days later my check engine light came on.Tryed self-diagnostics counting number of flashes - it did not flash
Went to a shop, they read the code P1491 = EGR valve insufficient opening. They removed the valve, broke the gasket, could not find a replacement, ended up blocking intake and exhaust openings with a piece of sheet alluminum and simply bolted the valve back on top.
Is this OK? How long can I drive like this??

After re-setting the code the light came on again 10mi later.
After all this I still have the rpm drops.

The main question is can this be some other problem with idling?
As far as I understand, EGR valve only opens up at cert. temp and high RPM, so why do I have rough idling drops when EGR is blocked? I dont want to pay around $150 for new EGR just to learn that there is something else is wrong with emission system.

Thanks

 

The egr can provide an idiling problem if it is open at idle, but since they blocked it off that shouldn't be your idle issue, all though make sure they fix that problem because you won't pass smog and your check engine light will never go away since it doesn't see your egr valve opening or closing. As far as the idle dropping there can be any number of reasons for that happening, first thing I would do is go back to the shop force them to fix your egr or tell them your going to the b.a.r. and reporting them for tampering with your emiission systems. Then take it to a smog repear station and tell them to properly check your egr system to make sure it's fuctioning properly because if it is open at idle it will drop the rpms possibly kill the engine or sometimes create a stumble on accell. If that doesn't take care of it maybe you have some dirt on your idle air control valve and it's causing it to stick or something. Does the idle drop and then come back up, or does it drop and stay down?

 

Thanks for your reply!

The idle drops AND then come back to normal within 1-2 sec causing vibration on steering wheel. 95% of the time drop happens when:
1. coming to a full stop or
2. when switching gears from P to D or to R, and from D to R
Another 5% drops happen while idling with gear in D.

And whats is b.a.r. ?

Thanks!

 

The b.a.r. is the burea of automotive repair it's a agency that is out there to protect the consumer if you feel you've been mistreated by an automotive shop you can file a claim with the b.a.r. and they can get your problem resolved.
It sounds to me like your idle control valve is responding, but something else is pulling the idle down. First thing first I would resolve the egr issue because it could be related, but most likely it's another issue, like possible a fuel issue. You can check your idle air control valve by turning on your ac and making sure your idle kicks up a bit. It's not a defieniet test, but it will at least let you know that your idle air control valve is trying to do it's job.

 

Well, I did not have time to run a good test, but it looks like when my A/C kicks in, the idle goes up a liitle, just like it always did, and
when I disconnect IAC valve while idling the RPM goes up and then fluctuate above normal. This IMO means that IAC valve is working. But like you said, it could be an intermittent prob due to durty valve (why? K&N always cleaned properly) or faulty wire from IAC to PCM.
I will remedy my EGR problem first and then we will see

 

Did you ever resolve this? I have a similar problem.