Hi guys.
After reviewing the forum on EGR valve P codes, I purchased a screened gasket set from Amazon and installed the obvious one today after cleaning the valve. Have not driven it yet, as I am waiting for the code to reset after disconnecting the battery for awhile.

My question is this:
Two gaskets came in the package. I am now left with the one that is about one and a half inches wide and 4 inches long. It has a raised domed screen (not flat like the other). The package instructions indicate nothing regarding its use. Is there an application on my 1999 Blazer for this? What is this gasket for?

I have a new EGR valve installed in Florida with about 6,000 miles on it. Noticed my gas mileage drop and some hesitation at times, now here in Minnesota. Carbon chunks in the pintle made some sense to me. Hence, the project.

Thank for the help - AGAIN!!

 

Disconnecting the battery does not reset anything. It will turn the SES light off only if there are no hard faults present, but the code will remain in memory regardless. If a problem is detected while a monitor is running, the light will come right back on again, and set a code in memory.


The triangle shape gasket is the one you need. The oval shape gasket is not used on your engine. Carbon chunks could be due to Winter blend fuel used in Minnesota, (not used in Florida). Summer blend fuel doesn't arrive here until later in March.

 

Thanks Captain.
I was suspicious of the fuel, especially since my driving has been also fairly short trips. I will see if I can get Auto Zone to recheck & reset the codes. If it reoccurs, I'm not sure which is the next logical step, since there are other things a p0404 can mean, I guess.

 

When it comes to DTC's, keep in mind that the first one retrieved must be diagnosed & repaired, then all of the memories cleared, and a drive cycle performed with no failures, before any subsequent DTC's can be diagnosed. Any codes that are retrieved after the first one, can be caused by the first one.

 

Ok Captain. That is VERY helpful. Thanks for the follow-up.

Another question:
In your opinion -
What is a realistic MPG for a well-tuned 1999 Blazer with standard tires (Cooper AT) driven in a normal fashion at posted highway speeds??

Thanks

 

I have a 98 and an 04. Both have 3.42:1 gears. The 98 has the NV233 2 speed selectable transfer case with open differentials. It will consistently get 23+ mpg on the freeway. Been as high as 24 point something. The 04 has the NV236 auto 4WD and limited slip differential, (considerably more drag). That one consistently hangs right around 21 mpg on the freeway. 65 to 70 mph using cruise on both of them. Both of them around town suck, usually 14 to 17mpg, on a good day. Depends who's driving, wife ALWAYS gets better mileage than I do


I'm real fussy about how they run, and it takes some "tweaking" with the scan tool, but everything is bone stock on both of them.

 

WoW! I feel lucky to get 14 mpg and I've done everthing from new spider, plugs & wires, distributor, fuel pump, fuel filter, Egr valve, air filter, tires, etc.

How do I know if I have a NV333 or NV336??

 

NV233 has 3 buttons on the dash switch, NV236 has 4 buttons.

 

Then I have a NV233 and should be getting a lot better gas mileage.

Since I cleaned the EGR valve and replaced the gasket with a new screened one, the Blazer seems to be running better(less stumble/hesitation). I still have to get the P code cleared. Can you think of anything else I might be missing in order to get better gas mileage? Assuming I don't get any other P codes.....

 

There are a ton of things that affect fuel mileage. Although it will monitor many things, and alert you of a malfunction, the OBDII system is not the only cause for crappy mileage. It's a good start if the SES light is off though Fuel delivery system, camshaft retard, wheel alignment, tire pressure, brake drag, transmission torque converter not locking up, incorrect crankshaft position sensor relearn data, front axle must be disengaged in 2WD, vacuum leaks in the HVAC & 4WD systems, etc etc. Plus a bunch more, that's just a start.