rough idle again

[JS567]

I have a 95 blazer 4.3 w vin. with in the past year and a half I changed the egr valve because it was running bad. After that it ran good. Then 2 months ago the it started doing the same thing, changed the cpi and it ran good again. Now i drive and when i stop it almost stalls and runs really bad. also the exhaust really smells bad. Then the ses light comes on. This only happens sometimes. its not a constant thing. I was going to go to autozone to have the code read but the light goes off and then it runs good. any suggestions?? The cat was changed at 78000 and it has 87000 miles

[rlith]

Did you change the nutkit when you changed the CPI??? You mention bad smell...Like rotten eggs? Could be a clogged cat... Even though you changed it, if you are running too rich, it can reclog the cat... BTW, even though the SES light is out, there is a code stored.... at 87k your 02 sensors (all 3 of them) are due to be replaced... Edpecially if this is causing a rich condition...

Your CPI could also have gone bad again... Pull the upper plenum... Look for signs of washing. (where one side is cleaner than the other) If the driver's side is washed, then your nut kit is leaking (causing a rich condition), if the passenger side is washed then the CPI failed and you should be able to replace it under warranty. When was the last time you switched out your cap/rotor/plugs/wires? Have you pulled any of your plugs to see if they're fouled? (Again, this would indicate a rich condition)...

[JS567]

Just came from autozone code was PO1406 any ideas where to start?

[rlith]

well, there is no po1406, it will either be p140 which is a bad 02 sensor (bank 1, sensor 2) or po406 which is a malfunctioning EGR.... So which number is it?

[JS567]

It Was P1406

[JS567]

How Hard To Take Off The Egr And Clean It?
I Want To Save A Few Dollars And Do It My Self.

[rlith]

Fairly easy, 2 10mm bolts... Also a note about your particular code from an online shop... Essentially though despite what it says below, pull the egr and clean it with a wirebrush and carb cleaner, make sure the pintle is clear..

As is so often the case, several factors can cause poor EGR performance. Carbon buildup may be cause the pintle to stick, leading to a code P1406. In this case, cleaning carbon buildup off the pintle will clear up the problem, at least temporarily. To help address this issue, GM has reprogrammed the PCM in an attempt to “knock off” excess carbon, using quicker pintle movements designed to reduce carbon buildup. If the only cause of the P1406 code was carbon buildup, the PCM can be reflashed (reprogrammed) at a factory dealership. In fact, all the P1406 codes that arrived in our lab had already had the reflash performed.

However, some EGR valves seem to stick due to normal wear. In these cases, cleaning the valve will not improve the pintle response time, and the valve must be replaced to prevent the P1406 code from reappearing.

Due to the intermittent nature of this problem, clearing the code could appear to be a successful repair. It may take several test drives before the EGR valve finally sticks, and sets a new P1406 code. Technicians must learn to be wary of simply clearing a code and shipping OBD II equipped vehicles. Our research indicates these vehicles will be back, with the identical complaint.

[crank182]

Yeah for 95 and up it is OBD2, and yes there is a code 1406, the code failure is EGR Valve pintle position circuit failure, so you were right on it for the EGR valve, and yes it is easy to clean, just some carb or break cleaner and a wire brush, try not to get too much spray on the vaccum diaphram, it has a chance of dryrotting it. Good luck.

[rlith]

Originally Posted by crank182

Yeah for 95 and up it is OBD2, and yes there is a code 1406, the code failure is EGR Valve pintle position circuit failure, so you were right on it for the EGR valve, and yes it is easy to clean, just some carb or break cleaner and a wire brush, try not to get too much spray on the vaccum diaphram, it has a chance of dryrotting it. Good luck.

Only some 95's have ODBII (first implementation, ECM located under the hood, distributor is side post mounted) Some have the dreaded ODBI.5 which es enhanced ODBI (ECM located under the hood, distributor is top post mounted)

[vballfun]

I've had the same problem.. where the SES comes on for about a day.. and then goes away.. and while it's on.. it rough idles.. almost to stopping. and has happened for the past year and half every 4 or 5 months and I usually notice it right after filling the gas tank. So I've always thought I was getting some bad gas cause it would go away by next tankful. But now It happend again and I got it to autozone in time and had the same code (among others) p1406 (and p0134 (O2 sens), p0172 rich mix, p0300 random misfires, and p0401 egr flow insuff.) So.. looks like I'm gonna try cleaning mine up as well.
Tim