wait let me get this strait, your original ecm was bad, and the used one you had was bad also. they tried one of their ecms and it threw an O2 code. so you swapped some computer chips between your ecms and had them reset it and good to go? were they sending you home telling you that you needed a good ecm?

 

No no no...

First, remember that I only paid them for a full diagnostic. Not to actually fix anything.

the original ECM = truck running super rich. could not even be read by the testbook.

The used ECM = truck would not start for them.(It had started and drove with me just fine when I dropped it off and was the ECM in the truck when they started the diagnostic) Was readable but not by testbook... tossing some errors of it's own.

The dealers ECM = truck ran. Dealers ECM has known burned out O2 circuit and can not be used for testing the O2's... (constant 02 code) They never get D1's in, and don't really have a lot of parts laying around for them for testing)

There conclusion was both ECMs where bad (but in different ways) and that the O2 sensors should be replaced due to the massive over-fueling and subsequent loading up they would have suffered from it. (and age) They drove the truck over to the waiting area on their ECM, then put the original one back in. Let me again say, that they never used the actual testbook laptop as it would not read the ECMs and ended up using their handhelds for everything... I need to find out exactly what handhelds they where using cause it was able to do everything...

I had to get it home, and had seen how much better it ran on the used ECM, so I swapped them. (And changed plugs with a set I cleaned on the spot cause the truck refused to start after they shut it off).

All the swapping of the ECMs in and out durning the testing locked out the truck security system. Meaning you could turn the key and nothing would happen. turn it again and it might turn over but not fire... etc.

I swapped the EPROM's thinking that would be enough, but it's not. So, it needed to be reset via the testbook and matched.

I'll take some pictures of the inside of the original ECM and you will clearly see why I did not want to put it back in. Green corrosion, dirt etc... From the outside it looked fine...

After the reset and matching, the used ECU was reading fine, and the truck fired right up and drove home fine. (The dealer had not done this step, under the assumption that the ECU was no good). It was only becuase of my wanting to put the used ECM into the truck for the drive home, and taking them both apart on the spot to try and manually unlock the security system that finally prompted them to try and completely reset the ECM. (I was doing all this work right in front of the service bay with the mechs watching...)

Even the mechanic commented on how it was a great Idea after the fact and he had not thought of it... We talked for some time after Good guy over there btw... keep in mind, that neither the mechanic that worked on the truck, a second mechanic that was assisting nor the service manager thought the security system could be locking me out. "It just doesn't happen"... Well, it does...

I've seen the 02's myself... even cleaned them once already, using a torch and brush. By now they are again full of soot and buildup just like the plugs where getting. I also have no idea how old they are. Swapping in 2 new ones in the front will do nothing but good. I'll be driving the truck some today, pulling a trailer etc, and will see if it tosses any CEL.

Ordered a full set of D90 springs from Will Tillery last night to fix the massive lean the truck has. Other parts ordered and on the way for the 02 sensors, fuel system etc.

 

No clue what's going on. Glad you got it working IF it's working. One side note is the truck should NOT run if the ecu and alarm ecu do not match.

 

Correct. It would run like crap with the original ecu, ran at first with the replacement, but then stopped working (locked out) But ran again with their test ecu... ??? Anyways, it seems to be working great. I just did a 2 hour round trip in it pulling my trailer to go and get a big wooded bunk bed setup. It's still a little rich, not blowing smoke rich, but o2 sensors need to be replaced rich.

Went though about 8 gallons of fuel. Can't really be totally accurate there, cause I can not fill up the tank, but I had a quarter tank, put 10 gallons in and when I got home I was above where I had put the 10 gallons in.

google maps says-
I-59 N and I-24 E
57.6 mi

so say 120 miles round trip total, and around 8 gallons of fuel... thats about 15 mpg...

Livable, but should do better with the new o2's. It's just rich enough right now where it kind of burns your eyes to drive it...

I attached a few picture of the load...

 

Congrats my man, looking good! I can now feel at ease with the '97...

...and heck, 15MPG?!?!?! Take that and run!

 

LOL... it's getting sooooo close... Some o2s, the d90 springs, the fuel filler and vent tube, and the rear quarter and door window gaskets. I'm honestly thinking about taking it down and reshooting the white paint on it and having all the little dings fixed...

It's looks pretty good as is, I actually got a couple different thumbs up on the drive today... and yes, they where thumbs....


But, no, wife hates the headers and the flowmaster 40... says it's too damn loud for her. Wants the other one back... So now I'm hunting for something else for her again...

 

Sounds great. Happy t ohear it wasn't so major after all. What a story.