Hey guys, this post is for a 1997 Honda Accord LX:

Today I went to Schucks and used their emissions test,
it came up with the code P1491 so I went on the website and it said:

P1491
EGR Valve Lift Insufficient Detected

How can I fix this problem? I'm not even sure what this part is or
does but I'm always down to gain more automotive knowledge.


ALSO, the CAT - EVA - O2S buttons were flashing as well. Just guessing, but the CAT = Catalytic Converter (I know why this is lit up)
and the O2S = an o2 Sensor, but I'm not sure which one.

The question I had about this was what does the EVA stand for?
And how might I go about checking/fixing this?

Please let me know if any of you have some ideas.

Thanks!

 

EGR valve stands for Exhaust Gas Recirculation valve. This valve is used to direct part of the exhaust gases back into the cylinders via the intake valves. This reduces the amount of NOx that comes out of the exhaust pipe. Unfortunately this leads to buildup of carbon deposits in the intake manifold near the inlet valves, or the EGR valve itself gets stuck over time.

EVA is the fuel evaporation canister: fuel vapors from your fuel tank are stored in a little canister and on regular intervals this canister is emptied via the intake system. The fuel vapors are burnt along with the rest of the fuel.

So both EGR and EVA are systems which are supposed to make our engines a little more friendly to the environment.

 

Search for EGR in the Accord FAQ section

 

The '96 and '97 Accord F22B2 has had (at least I've seen) repeated problems with P1491 caused by a faulty lift sensor; which is incorporated in the EGR.
I've had them fail in all manner of ways; my favorite was one which had a fixed value high, causing the ECM to fail to ground regulate the EGR solenoid.
It originally tested as a bad ECM. Fortunately I had a known good used unit and used it to diagnose the thing. The customer avoided the cost of an ECM.

What you're going to need is a scanner that can display the sensor's voltage. I found this particular problem once I noticed the value was fixed, regardless of what was happening.

P

 

Thanks Danny/P Adams. Would this be effecting the idle at all? I just replaced the valve cover gasket/spark plug o-rings because oil was leaking into one of the spark plugs. It fixed the leak, gave it a little more power getting up hills, but it didn't fix the idle problem.

I will be sitting at say a stop light, A/C is OFF, the engine will be idling normally around 500 RPM. Then randomly dip down to 100-200 RPM and almost kill the engine, then it catches itself and returns to the normal idle.

 

Checking and cleaning the EGR valve may well solve your low idle problem. Don't forget to clean the EGR ports in the intake manifold as well: these too get clogged over time. As accord_raffi pointed out the Accord FAQ has plenty of information about cleaning the EGR valve and ports.

Good luck and keep us posted about the results (I had similar problems on Acc '99: low idle and engine hesitation to rev up from idle).

 

I would suggest cleaning both the throttle body and IACV (Idle Air Control Valve) before you attempt to clean the EGR.
You're idling too low; you should be sitting steady at 700rpm, with slight recoverable variations whenever the A/C or the cooling fans turn on.
It sounds like the throttle plate's crud-ed up and the entire idle air flow is now being handled by an overworked IACV.

The procedure to address this is discussed in the FAQ thread at the beginning of this sub-forum.

P