tortis

this is a 99 accord I4
egr valve is new, cat. is new, 1st o2 sensor is new.
what else could make it throw this code?
i don't see where i can get to egr ports to clean them. i am at a loss here.
thanks for any help.

Turbowa

You will have to remove the intake manifold and clean out the ports. The main one from the head to the valve. Then take the maifold apart and clean out the second set of runners for the egr valve. There is alot of carbon that builds up in those 2 places. You may even need to drill out the main port some. Also clean out the port in the head.

tortis

is there any preventive measures to keep this from happening again. seems like this is a repeating problem.
man i don't want to take this car apart days before a major road trip.

tortis

all ports are clean. cleaned the connector that sits under the egr valve, and sprayed carb cleaner into the egr valve which was pretty clean.
i did find the clamp that connects the air intake to the throttle body a little looser than i like it. check engine light is off for now.

Mr Yamada

tortis

Thank You Mr. Yamada Sir. will take the TB off tomorrow and clean the that port.
thank you again.

tortis

You will have to remove the intake manifold and clean out the ports. The main one from the head to the valve. Then take the maifold apart and clean out the second set of runners for the egr valve. There is alot of carbon that builds up in those 2 places. You may even need to drill out the main port some. Also clean out the port in the head.

with Mr. Yamada's pic i see what you are talking about. thank you.

tortis

that area between the throttle body and intake was totally blocked. super thick black gunk. pine tar heroin thick. scraped and cleaned the bottom of the throttle body and cleaned the port in the intake manifold.


Modified by tortis at 2:59 PM 8/11/2008

tortis

well turned off the CEL, drove it 15 minutes CEL back on. autozone checked it and P1491 pops up. i just undid the negative battery cable, instead of the fuse, hopefully it just didn't clear out.


Modified by tortis at 3:00 PM 8/11/2008

tortis

alright, cel is on. P1491.

i am open to any ideas. i hate having my *** kicked when the opponent (the car) is trying to help. it has to be something simple.

AWest

I know this is an old post but I was wondering if you ever fixed your egr problem and if so how? I am in the same boat. Cleaned and replaced everything and I still get the P1491 code. Any thoughts anyone?

low'98

Same here. '98 Accord 2.3 4cyl VTEC. New EGR, New O2 sensor, Cleaned TB, upper IM. Removed tons of black gunk. Still throwing P1491.

AmunRa

Any Replies????

gcondo

I too am in this boat. Could it be a battery voltage issue? Vestigial data in the computer's memory that only dealers can erase issue? After cleaning the carbon/tar out of the EGR valve & port/plenum (P0401 code) I had been starting the car by first putting the switch to the on position, waiting for all the bings and flashing lights to cease, then starting. I probably did this for a week each time, but then forgot and just started the car. Only after that did the CEL rear it's ugly head and before that a maintenance required light (unrelated?). Bad EGR?

brakedrum

If the passages are clear, and the EGR valve itself passes the vacuum tests, then you have to delve deeper.

The EGR control solenoid which is inside the control box on the firewall. On my year it is a kind of triangular shaped black box with hoses and wires attached to it. It's above the fuel filter and you have to unbolt the box to open it and get at the things inside it. That may differ on newer Accords.

There is a test for the EGR control solenoid to determine if its functioning properly, but too complicated to explain here. Of course, since this is emission systems stuff, it's not going to let us off easy, so to round things out, there is also a constant vacuum control (CVC) valve inside the control box that's also involved in monitoring and controlling exhaust gas recirculation. Speaking of that solenoid, I have actually parked my car after fairly long drives and heard it make a distinct "pop" as it returns to position after doing the EGR thing.

The codes, P0401/P1491, Insufficient Flow/Insufficient Lift, are vague. One would think it would be impossible to have one code without the other. The mystery is inside that control box.

Best suggestion is to get a repair manual and read the EGR section a few times and then grab a multimeter, pump-type hand vacuum tester, etc. and delve in and test that whole system.

gcondo

Thanks, breakdrum. I don't know why but the light went off on it's own. All I did was snug up a couple vacuum hoses that seemed snug. My EGR doesn't have hoses to it. Maybe it was the Seafoam left in the tank working to clean things. Now if it would stay off.

brakedrum

If your EGR valve has no hoses attached, then it can't operate when the EGR solenoid applies vacuum to it. Obviously the Lift Sensor that crowns the EGR valve would not report mission accomplished to the ECU. A CEL is guaranteed in that scenario. If your EGR valve has been blocked off, then it sounds like the ECU is still looking for it and will place that code and illuminate the CEL every time that EGR solenoid applies vacuum and gets no information back. Blocked off, of course, means no EGR flow at all.

hondamark35

i'll second that. getting the good one (Helms for around $60-75 used) pays for itself pretty quickly.

i looked through the troubleshooting procedure for P1491 briefly and it's pretty long, heavy use of the multimeter and starting the engine and running at certain RPM... but the results of most of the testing seems to lead to either a bad ECU or an open or short somewhere between the EGR and the ECU. If you can get your hands on a known good ECU, try swapping it out and see what happens. Also check all the wiring as well as you can for any looseness, breaks or other damage.

gcondo

This model ('02) does not have a place to attach a hose to the EGR. CEL is still off. Thx.

momsminivan

For Tortis!
if you have gone thru and cleaned the EGR, Cleaned out the ports and checked the Vacuum lines heres how i got my light off afterwards.

unplug the power to the egr, turn on the ignition and the light should be off.
Turn the engine one for a sec, then turn off.
replug your power to egr and you should be set.

Worked in My Moms Honda minivan LOL

useraale

Tortis did that work for you? I have the same problem

96odysseyjdmf22

can we get an update on what happened if possible?

budduz

I have the same problem right now w my 98 Accord LX. What do yall think of instead of removing the throttle body, I drill straight down through the TB into the EGR channel and clean it out that way? When I'm done, I'll tap it so I can screw a bolt in there and have easy access if I ever need to clean it out again.

Let me know what you think?

budduz

And I also have 1491 coding and the EGR works. I took the egr off, ran the car and the EGR is responsive to throttle changes. However, there is no suction from the EGR port into the intake manifold so it must be clogged. I sprayed some carb cleaner in their, let it soak and was able to remove some gunk with a guitar string but I wasn't able to get through all the buildup and reopen the channel.

MAD_MIKE

If your car is the four cylinder, the easiest way to clean the EGR port is to remove the upper plenum from the lower plenum, and remove the EGR valve.
Clear out the single port going up into the plenum down to the EGR.
Gasket is about 5 bucks.

If the V6, you will need to remove the upper plenum from the lower plenum to clear out the port.

I would not do any drilling or tapping, that is much harder than simply removing the upper plenum and clearing out the port properly.

Check out the FAQ at the top of the page, think post 20 in the how to clear the EGR is where the 98-02 how to starts.