Ok Captain. I plan on getting the SES code reset today. I have a new fuel pump, as well as items previously listed. I don't think I have any of those other issues, but I would probably need a "real" mechanic to check that stuff out.

Do you think that taking the vehicle to a good shop would likely help much? I mean, it's not really like in the "old days" when the mechanic could actually "tune" the carbs and tweak the timing, etc. Right?? Or, is there actually equipment or devices that can adjust or fine tune things like on-board computers or software?

Perhaps, things will improve when the summer fuel blends arrive.

Your thoughts are always appreciated Thanks.

 

There are some things that can be tweaked, but they require a high end scanner, and someone that knows what to look for, what to do, and how to do it. Several members here have gone to the dealer for some of these tweaks and the dealer is unaware of them. Just depends where you go. Who ever you have look at it, needs to be very familiar with this engine. If you can get your hands on a high end scan tool, we can walk you through the "tweaks", they are not difficult at all. Autoenginuity makes a very good software program for laptops.

 

Sounds like I have to do some detective work for a 4.3 guru around here. I'll work on that. i got the Po404 code cleared yesterday and so far, so good.
thanks for all the good advice.

 

The EGR sensor circuits are monitored continuously, but the flow is not. The SES light will remain off until the EGR monitor runs, completes, and detects a problem with flow. If you perform the General Motors Driving Cycle it will force the monitor to run its tests. Each step outlines what things are tested in it.

 

Well, Capt.--
My SES light is back on again, so I guess cleaning the relatively new EGR valve isn't the solution. Maybe, it's defective. Is there a simple way to check it, other than swap it out.

I intend to run through the Drive Cycle Instructions you provided. Do I have to clear the code again before I do that, or can I just run the procedure, then have the codes read??

Also, assuming the EGR valve is good, what do think might be the next likely thing to look for? O'Reilly Auto provided a print-out of 6 "Possible Causes" and 25 "Reported Fixes", including PCM failure. I thought you might have an opinion of what might be most likely, as the vehicle seems to be running well otherwise

Thanks again for your response.

 

Post the DTC's in the order they were retrieved.

All memory files must be cleared before doing the drive cycle. It must be done with a scan tool capable of accessing all memories. The auto parts store scan tool is not capable of this. It will clear pending, and current files only, not the history files, which need to be cleared as well.


I get such a kick out of those print outs PCM failure is so rare on these things. Don't get yourself in a tizzy, chances are slim to none that the PCM is faulty.

 

Captain, I'm trying to get 3 monitors to reset after doing a valve job. Is this why they will not reset even though I am doing the GM Drive Cycle several times?

 

Very helpful Captain. Looks like I might end up going to a shop, but will consider buying the Autoenginuity scan Tool. But having the tool doesn't mean "I" can fix the problem.

 

The PCM continuously monitors several circuits, (MAF, MAP, BARO, TPS, EGR, ECT, IAT, O2 sensor, etc etc). The monitors test the operation of the "systems" and each one is tested only under certain driving scenarios. The purpose of performing the drive cycle is two fold: #1. It forces all of the monitors to run and complete their tests. #2. If no new DTC's are set, that will tell you if you have made a successful repair to a specific problem. If you don't clear all of the memories before the drive cycle, you have no way of knowing which are old DTC's and which are new. Gotta start with a "clean slate"


If all of the monitors don't run and complete during a drive cycle, there's only one explanation..... you didn't perform the drive cycle exactly as outlined The steps do not need to be performed in order, but each individual step must be performed exactly as written from start to finish. At the end of each step, it tells what monitors will run during it. Some systems require more than one step too. If you only need 3 to complete, you only need to do the steps that affect those particular monitors.

 

Thanks for the great explanation. Things make much more sense now, especially the Drive Cycle procedure. I will try to get a good shop to clear the codes and go from there. It is starting to warm up a bit here in Minnesota, maybe 60 degrees, so I am hoping to tweak a few things on the Blazer during this balmy weather.