1997 Lumina 3.1 EGR Code 0401

[Myxlplyxxx]

I recently got that NASTY code 0401 on the ODBII scanner which is (EGR insufficient flow) Ive tested the unit and it checks out fine but, the passage to the intake from the EGR was Clogged and caked with stuff u only see in HORROR movies.... I cleaned it out and had the car code cleared.... after a longer than usual period of time(about 20 miles this time) the code came back (SES Light)... any Ideas??? Try cleaning it again??? What is the best stuff to use to clean it??? really dont wanna pull the throttle body to do it so and ideas would be well welcomed.....

Thnx MYX

[cadgear]

Sure its the same code?

The PCM does a flow test on deceleration from at least 50mph at less than 1% throttle angle. It then commands the EGR to a percent, and monitors the MAP for a change in pressure based on how much the EGR is commanded open.

Double check the valve itself to see if its stuck from carbon or anything else. Another idea would be to check the EGR pipe for exhaust pressure when running. Just pop the valve off and see if you get the unmuffled exhaust.

[bound2luvu]

Originally Posted by cadgear

Sure its the same code?

The PCM does a flow test on deceleration from at least 50mph at less than 1% throttle angle. It then commands the EGR to a percent, and monitors the MAP for a change in pressure based on how much the EGR is commanded open.

Double check the valve itself to see if its stuck from carbon or anything else. Another idea would be to check the EGR pipe for exhaust pressure when running. Just pop the valve off and see if you get the unmuffled exhaust.

I am having the same problem with my 1997 chevrolet lumina, I have bought a new egr valve and installed it and had the the code light turned off (service engine soon) and within 1 day the service engine light came back on, with the same egr code, so I took the egr valve back to the automotive place and they replaced it with a new one, and the new one has been installed and wouldn't you know it after a few hours same thing happens again, the service engine soon light came back on with the same code message, can someone please help me, this is driving me crazy, I am not a mechanic so any help would be greatly appreciated. Ty

[cadgear]

Ensure the passage itself from the valve to the manifold is not plugged with carbon. What sort of mileage do you have on the car now?

Some carb cleaner (brake clean works too) and a guitar/piano/bass string will work wonders on that passage.

[MS99XLS]

I've tried unsuccessfuly to take the EGR passage appart for cleaning, can anyone tell me what would be the easiest way to do it? I can detach it from the upper side, no problem, it's the lower side I just can't get done. Is there a special tool or what's the trick?
Any help will be greatly appreciated !!

[cadgear]

What year?
If it's the 95+, you just gotta be patient with the string/wire/whatever and keep the throttle plate blocked open, clearing as much carbon from the intake as you possibly can (not good for the chunky stuff to be sucked into a cylinder).
Earlier years is just a straight-through, not L-shaped. You should have less/no problems with that model.

[richtazz]

Double check the vacuum line supplying the MAP sensor. A crack or leak in that line will cause a bad signal to the MAP, which can cause an EGR insufficient flow code. It's more common on the 97-up 3.8's that have the MAP on top of the PCV housing, but if your EGR passages are clear, it's another thing to look at.

[MS99XLS]

Thanks for the response.
Maybe I didn't express myself correctly, what I need is to detach the EGR passage from the block, I can detach the top end but haven't been able to figure it out how to detach the bottom end. How have you guys done it in the past? What tool have you used? By the way, its a 95 Lumina (car, not a van). Thanks.

[cadgear]

The 'bottom end' if I recall is cast into the upper intake manifold. You can't take it off unless you take the whole UIM off, and even then you're at the mercy of nimble fingers and deilcate cleaning.

If its just you, and you have no way of blocking the throttle plate open, take the TB off and attack the problem that way.

I know, inconvenient. But hey, its brilliant engineering, right?