On Thu, 17 Apr 2008 22:18:43 -0400, "Kevin" <nunya (AT) somewhere (DOT) com> wrote:

No idea about that code, sorry.. but the screen keeps carbon from getting TO the
EGR valve, so it doesn't bind up..

Our 95 blazer would get a "check engine soon" light and idle very badly and have
no power brakes at low RPM..
Had the EGR valve replaced and it the problem went away for a while, then came
back..
I cleaned the little pin in the valve and the problem went away again but came
back..
Steve recommended the Klean screen to replace the EGR gasket and the problem has
been gone for about 2 years..

http://www.sherco-auto.com/klean.htm


mac

Please remove [dot]splinters before emailing

mac davis wrote:
P0404 is EGR Circuit Range/Performance.

Nothing to do with cylinder misfire. That would be code P0304

--
Steve W.
Near Cooperstown, New York

"Steve W." <csr684NOT (AT) yahoo (DOT) com> wrote

Ooooops!!! That would be correct, P0304 is my usual code if the engine
doesn't get "driven" every so often. 8-) I was even questioning myself
while reading the P0404......

On Wed, 16 Apr 2008 22:18:59 -0400, "Steve W." <csr684NOT (AT) yahoo (DOT) com>
wrote:
OK, I verified that the code was indeed P0404. I bit the bullet and
did the top engine cleaning. I went to the GM dealer and tried to buy
TEC. They told me that it is not made anymore and gave me the "new"
replacement called "Upper Engine and Fuel Injector Cleaner" -
#88861802. I rigged up nice little funnel arrangement and slowly
poured the stuff in through the brake booster line.

Ultimately I poured the whole container in there and let the truck sit
for an hour. I started it up and it did the white smoke thing. I
decided to drive the truck rather than smoke out the neighbors. It
did seem to make a lot of white smoke. I also did some driving at
wide-open throttle. I forgot just how anemic the old 5.7 really is.
In any event, I can't tell any difference. . The engine still had
some EGR like symptoms … stumble/surge when you give it a little gas …
just off idle. Otherwise the truck runs OK ... not great … but OK. I
will change the oil tonight ... spark plugs seemed to be OK

Next, I took my previous EGR valve that I had cleaned with carb
cleaner … lots and lots of carb cleaner. I put that in with the Klean
Screen. I also cleared the P0404 code (so the check engine light is
out … for about a day or so). I can already tell that the "cleaned"
EGR valve is no good. The engine still stumbles/surges when you give
it a little gas … just off idle. So … I went to the store and bought
another EGR valve. I already know that when I put the new EGR valve
in the engine will not stumble/surge at all (since I have already done
this … twice before). .

My best guess is that none of this will have any long term effect. In
two months the new valve will be fouled. It would be great if the
cleaning and/or the Klean Screen solves this problem. Only time will
tell.

Thanks,
Dan

On Sat, 19 Apr 2008 16:02:16 -0400, dan (AT) somewhere (DOT) com wrote:


Dan.. I had different symptoms, besides the "check engine soon" light, the real
rough idle and no power brakes at idle, nothing else was effected..
The truck ran fine except at idle, brakes were normal unless at idle, (and after
the first pedal push and release), and the fuel economy was normal..

I took the EGR valve out twice and both times the pin was frozen from carbon..
After putting the Klean Screen in, it's been trouble free for about 2 years
now..
Hope yours is too!


mac

Please remove [dot]splinters before emailing

OK, I put the new EGR valve in. Of course the truck runs correctly
now. No stumble/surge at any RPM. Idle is very smooth. Most likely,
by June 19 the new EGR valve will be fouled.

I believe that my engine is making lots and lots of carbon. This is
obviously what is fouling the EGR valve. I also believe the top
engine cleaning and the Klean Screen are most likely irrelevant. It's
not chunks of carbon fouling the valve. If this were the case, I
should have been able to clean my old valve (i.e., wash the chunks of
carbon out) and the valve would have worked again … but it didn't.

So my theory is that the gasses flowing though the EGR passages simply
foul the EGR valve … within two months. Whether the passages are
clean or not, those "toxic" gasses are going to flow through the valve
causing it to foul. I'm guessing that either i) the engine is
basically worn out or ii) there is something wrong with the way the
intake manifold is installed.

This truck has had a lot of problems (way too many). I bought the
truck new it now has 118K miles. It is pretty much always "broken".
It runs … it's just never right. The "service engine soon" light was
mostly on for the last 80k miles. No matter what I fix … it does not
last and that service engine soon light comes back on within a month
or two. For the most part the truck really never ran right. My wife
drives it most of the time and she does not really notice or care. I
usually hate driving the thing since it usually runs crappy. I went
through the whole random misfire fiasco … too much to detail here.

Anyway, once I got the injectors changed the engine finally ran OK and
life was good (for a few months). But then it started leaking coolant.
Of course it was not the water pump … again … this time it was leaking
coolant from the block, at the intake manifold. So the local mechanic
changed the intake manifold gasket and the leak was fixed. But its
been EGR hell ever since. I took it back a few times … again too much
to detail here.

So I wonder if it is possible to screw up the installation of an
intake manifold and cause all kinds of horrible fumes to flow into the
EGR passages. If this is possible, perhaps I need the have the intake
manifold done again (only correctly this time). In the alternative I
could try to make some sort of bulk purchase of EGR valves (since I
will need 6 of them every year).


Thanks,
Dan

dan (AT) somewhere (DOT) com wrote:
Yes it is possible to screw up the intake gaskets. Do you notice and
white or blue smoke from the exhaust? If your not using coolant or oil
at a rapid rate I would guess the gaskets are OK.

It is also possible that the valve you purchased just failed.

The gasket is mainly to keep chunks of carbon from sticking the pintle
open. The top end cleaner dissolves the carbon and allows it to blow
through the system. It also cleans the valve heads, rings, and passages
where the carbon likes to build up.

--
Steve W.

On Sun, 20 Apr 2008 09:27:02 -0400, "Steve W." <csr684NOT (AT) yahoo (DOT) com>
wrote:

Yep, I'm sure the TEC cleaned the combustion chambers. This is
certainly not bad. I'll bet there was carbon in there. But it does
not really make a noticeable difference when you are driving. The TEC
did not clean the previously fouled EGR valve and I was unable to
manually clean an earlier fouled EGR valve with carb cleaner (i.e., an
entire can of carb cleaner).

I installed a brand new EGR valve and of course the engine runs
"perfectly" … or at least as good as you could expect from a 1999
5.7l Vortec. The truck does not seem to be using fluids or blowing oil
smoke from the exhaust. It seems to run perfectly fine (with a new
EGR valve) … so I am a bit puzzled as to where all this carbon is
coming from. I should probably talk to the local mechanic. He spent a
lot of time on this truck (as did I). I mean, I bought a darn code
reader six years ago just so I could figure out why the service engine
soon light was always on. And I used that code reader a lot over the
years. The local mechanic fixed lots of problems over the years at
very reasonable prices. But this EGR thing has just sucked. He lost
a lot of money trying to fix this truck (cause I kept bringing it
back)… I'll be lucky if he agrees to work on it again (I wouldn't if I
were him).

I took a drive this morning and I actually enjoyed driving the truck.
If you press the gas pedal (even just a tiny bit) you feel some
acceleration. That is, the truck actually responds. Once the EGR
valve starts to go, you just don't feel the responsiveness and often
it is opposite of what you want (i.e., you depress the gas pedal and
the truck actually decelerates or hesitates or surges …). With the
new valve, the truck feels 500lbs lighter … it's like a whole
different vehicle. It can even go up hills without dropping out of
overdrive.

The drivability issues I have with this truck are kinda my fault. The
5.7liter engine was never really adequate for a vehicle this size. I
really knew this when I was buying the truck. I should have bit the
bullet and sprung for the 2500 with the 454 engine. Of course the
2500 is super major overkill for my needs (and gas mileage would
probably be worse than the 5.7l … if one could actually imagine that)
but at least I would have been happy with the power output.

So for now the truck is technically "not broken." Since it is garage
kept, it looks almost brand new. It took it to the car wash, cleaned
up the wheels and tires, cleaned all the glass and vacuumed the
interior. So if I left it in the garage for the next six months and
didn't drive it … it would be pretty and "not broken" for six whole
months. But alas, we are going to drive the thing. I will post an
update when I have something new to report.

Thanks,
Dan