lfse

Hey yall,
Just swapped out my vss and i noticed that the vacuum line to the egr valve was cut and had a screw mounted in one end of it (assuming this is to maintain a vacuum?).
I've had my car (91 accord) for about 7 years now and, other than small maintenance issues, have had no troubles. So clearly the cut line is not keeping the car from working. I DO have a code 12 though and am guessing it may stem from this cut line.
Question 1) Why would someone have cut this line? Is it a performance thing or a lazy solution to a larger problem?
Question 2) Why does the car work without this line being functional? Does this mean there's little or no vacuum happening in the egr? What does that mean for the function of the engine? (i guess this is kind of question 1 part 2...)
Question 3) Should i replace the line? Doesn't seem like it should be too tricky... anyone replaced vacuum lines and can give me some tips on it?

All help is greatly appreciated!!

edit: link to pics - http://www.flickr.com/photos/8966384...ream/lightbox/

jdowen2

Seems like previous owner didn't want to replace EGR so just plugged the vacuum. I'm sure that if you reattach it you would have more driveability problems.

lfse

Planning to clean the EGR valve and ports as soon as my schedule allows. Once i do that should i wait and see if my cel clears and, if it doesn't, then replace that line?

Why is cutting and plugging that line a solution to an EGR problem? I'm not totally clear on whether that vacuum line is pushing or pulling through the EGR valve and what effect the absence of that push/pull has on the engine...

h0p3l355dork

A better solution would be to clean the EGR valve/ports and then unplug the battery to clear the CEL. If it doesn't come back, then you know it's resolved.

MAD_MIKE

The EGR not functional will not prevent the car from running. However, you may be experiencing some slight bucking or misfiring ~2000rpm. Being a code 12 is active, this does indicate that the ECU knows of a fault with the EGR system. Verify that your base timing is set correctly. If a previous owner disconnected the EGR valve, and they felt the misfiring afterwards the ignition timing maybe retarded.
My current crapshot theory is that the EGR solenoid or the wiring to it is defective in a way that allows constant vacuum to the EGR valve, when it is undesired. IOTW the person was too lazy to diagnose/fix.
The EGR system is used to dilute the incoming air charge during part throttle.
This dilution of spent/inert gases keeps the combustion temperature down to prevent the creation of excessove NOx. This gas compound reacts in the atmosphere to create acid rain, and damages the ozone layer.
If the line was simply cut, is not damaged(cracking) and can reach the other cut end, locate the appropriate sized coupling nipple from your local parts store and reconnect the two lines. Such as the yellow straight piece in this photo...


The hose size is 3.5mm or 1/8" if you cannot find metric sized hose.

But make sure the hose with the screw in it is the hose that goes to the EGR solenoid. There is a hose that Ts off the MAP sensor and It intentionally has a plug in it for testing purposes. All those items are in that area of that plastic box. Note #16 in the following diagram.


The two wire electrical plug connects to the EGR solenoid.
The three wire electrical plug connects to the MAP sensor.

lfse

This is all very helpful, thank you. Found a thread on the forum outlining how to clean/test the egr vac solenoid so think i'll do that this weekend and hope it's fixable (cursory searches show a new one to be $120-$200... no thanks).
Is it strange that i've been passing emissions tests with this blocked off? If i'm churning out a bunch of excess NOx, shouldn't i have failed something by now... or does it all still feed through the cat and get converted anyway?

Off topic: I SEE FOUR LIGHTS! (JLP makes me nerd out)

MAD_MIKE

It depends on where you are and what kind of testing is done in your region.
Do you have an actual emissions test, or do they pop the hood and just look to see that all the emissions equipment is intact, but not necessarily functional? If they do test emissions output they may not test NOx, and if that is the case, correct base timing may not be verified either. The catalyst if functioning correctly would clean up NOx but not as much as simple dilution through the EGR system.

HAH! I always forget about my avatar. The bottle seems appropriate.

lfse

In TX and i'm pretty certain they do an actual test rather than just a look and see under the hood. Guess the cat's been knocking out enough of the pollutants that it hasn't fouled the test for me (so far...).
Thanks for all the help

MAD_MIKE

Verify what kind of testing is done in your area. Some areas may only test HC/CO, others may test NOx, and the most stringent are not just idle/highidle tests but the 15/25MPH test.
At the least verify that your base ignition timing is set correctly.

Ronster65

FYI....The diagram of that box, which I have seen everywhere is the CONTROL BOX. These are the items inside it. Any one of these can go.

Its in plain sight but if you dont know what your looking for you would miss it.

Passenger side, Attached to firewall, beside fuse box, 2-10 mm bolts to remove it. Dont cut any hoses!!!

The box comes apart with 2 screws. The box is well designed to hold all these components. I can be a bit of a puzzle to put back together but not hard at all.

I went to a wrecker, took one out complete in 2 mins and installed in about 5. MAP sensor is in there but any one of these could be bad. Solved my Rough Idle issue.