[rjc]

Hi, I came to a dead end with this. P1404 EGR Closed Position. Stuff I've done to this.
I've tested EGR Checked OMH between pin A and E and I show just under 9 OMHS, (specs. between 8 to 9 OMHS). I do have 12 volts on pin E. I back probed Pin C and reads .9 volts (specs between .6 to .9 volts). I took EGR off and pushed pin in and that to is with in specs.

I would reset light, blazer will run about 40mi. then check engine light back on.
Intake is not plugged. I had it apart and was hot tanked.

wondering if EGR may still be the problem. maybe the solenoid in EGR if it has one is slowly going out? Anyone run across this issue in the past?

Any help would greatly be appreciated

 

[oldeerslayer]

P1404 CHEVROLET Meaning
The Powertrain Control Module (PCM) determines that the EGR valve is stuck open if the actual Exhaust Gas Recirculation (EGR) position and the learned closed EGR position vary by more than a predetermined value. The PCM tests for a stuck valve when the desired EGR position is at 0%. The PCM commands the EGR valve to 100% during certain driving conditions in order to clear a possible restriction from the EGR valve if the PCM determines that the valve is stuck open. The PCM retests for a stuck valve when the desired EGR position returns to 0%. A failure timer increments if the stuck EGR valve condition is still present. This DTC sets when the timer reaches a predetermined value.
In other words, when the PCM tests the valve position it should be reporting closed and it's not doing that, based on the voltage the PCM is receiving. Either some carbon build up is keeping it from closing completely or the valve is bad. Crud in there is a very common problem.
Have you scanned the system and done a freeze frame when the EGR is supposed to be open (cruising fully warmed up) and closed? Try testing the wiring by disconnecting the EGR. It should read closed.

 

[rjc]

Thanks for getting back, I have not done a freeze frame all I have is a Innova 3100 OBD2 Diagnostic tool. Ill see if I have that features to do that on the EGR. EGR bit pricy and wanted to make sure before I purchase one.

I am in the market on buying a good home diagnostic tool that can do more. Any recommendation? I was looking at the Innova 7111. I almost bought the Launch 129X but worries me not having support from the US even after reading good reviews.

 

[rjc]

I went ahead and replaced the EGR with a new one, I will drive around this evening and see if it made a difference. I'll let you know. Thanks

 

[oldeerslayer]

Finding a good scanner that will work on these old vehicles is getting hard to do. I use a BAFX bluetooth adapter from Amazon and the Torque Pro app from the app store. Less than $30 total and they'll do just about anything a scanner can for an older OBD2 vehicle. I also bought Car Gauge pro so I could read cam retard angle of the distributor. Either Torque didn't show it or I couldn't find it.

 

[rjc]

Ran the blazer this evening and check engine came back on. I've noticed driving it in town slower speed is when light is most likely to come on. I read somewhere that recommended to disconnect battery so computer would reset and relearn system. Is their a procedure to learn?

BTW Thanks on info on scanners

 

[oldeerslayer]

Got to get a code to know why SES light comes on. New EGR should be returning to 0%. Disconnecting the battery is an old school way to reset the ECM. It won't hurt to just take the negative cable off for 1/2 an hour. I'm sure some things will reset.

 

[rjc]

I give that a try. Thanks

 

[rjc]

well did all that I could and light still came on. code is still p1404. replaced EGR, disconnected battery for about an hour and still no change. One thing I did noticed today at about 50 miles and hour I noticed the rpm surged like a misfire but no other code came up,

Also when I replaced EGR with a new one today, When I started it up it ran a little rough and threw 2 codes p0300 and p0301 misfire.. I changed out for another one and it acted like original one I took out, Anything else I should look at?

Thanks

 

[oldeerslayer]

You got me stumped.

 

[rjc]

me too, what's chances PCM going out? Also noticed if I rev up and let go idle drops low like its going to cut out.

 

[oldeerslayer]

There's always a chance the PCM is bad, but it's no very common. Those black box ones were pretty reliable.
If you feel like throwing more money at it, spareecm has a good rep on here and they guarantee them.

S10 1999 2000 4.3L Engine Computer PCM ECM 16263494 99 -Programmed to your VIN # | eBay

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Or you could find a 99 or 00 one (not from a 2.2) in a JY for $25 and put your vin's program in it with a Tech2. If you're lucky you might find one in a 99 Blazer with the same code as yours. Yours has a tag and the last 4 letters at the top are the program, like CMUD or CDND or ?

 

[oldeerslayer]

Asked a knowledgeable friend about your P1404 and he told me there is a TSB out from GM. It's not that the PCM is bad, but it needs to be recalibrated to prevent false P1404's. I've attached a PDF of the TSB.
While searching for it I heard mention on the innerweb that there could have been a recall in which case the dealer would do it free. No proof that it's not an urban myth or wishful thinking, tho. The TSB does apply to 98 and 99 S and T vehicles which includes your Blazer.
here is a real in depth explanation of the issue:

P1404 – Exhaust Gas Recirculation Closed Position Performance (Buick, Cadillac, Chevrolet, GM, Pontiac, Saturn) – TroubleCodes.net

www.troublecodes.net

 

[rjc]

Thanks for the information. Pretty informative. I'm to a point now I just want to run vehicle and not worry about the light. I don't think I want to throw anymore money into it. Has not effected the run ability.

Thanks again

 

[oldeerslayer]

Since it could be a false code there's no reason you can't ignore it. You just get used to the SES light being on and you won't know if a new code pops up.
You might want to call your local dealership and see what they'd charge to simply update your PCM to the latest program, which I'm sure would include the EGR recalibration.

 

[rjc]

I was out earlier and SES light was blinking then came solid. code was still 1404 and p0300 random misfire. This just doesn't want to stop.