2-3 flare fixed!

[Larry Phillips]

I think I've got my transmission shifting correctly again, and I didn't even take it to the shop. I don't think this is the same problem that everyone else had. This problem was related to the cracked elbow on the vacuum tube. The only thing I can guess is that the vacuum leak (it was a pretty big leak) was so bad, that the EEC was using all it's memory trying to compensate, that it "forgot" how to properly shift the transmission. The problem that Jade was having was that on take-off, she would shift 1 to 2, then she would attempt to downshift into 1st as a passing gear, then hit 3rd. Now this would occasionally happen in differant gears, and depending on how slow I was going, I could actually get it to hold first gear a bit before shifting to 3rd. Since the computer forgot how to shift, I ended up having to ratchet shift manually from 1st to 3rd (by having to hold 2nd past it's normal shift point before popping to D). So all I did was replace the cracked elbow. About a week later, I decided to reset the battery, and after 100 miles, the problem resolved itself, and the tranny is shifting nice and firm again through all 5 gears. I'm still keeping a watchful eye on it though.

 

[Brandon Hovater]

Good to hear Larry!

 

[rob chaw]

Awesome...... Dude you lucked out BIG TIME.....

Good thing you like to tinker with Jade, cause it sounds like you got her all fixed up...

rob



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[Alan Peters]

Larry,



Can I ask where the vacuum tube (elbow) is located? My 03 is slipping a tad and would like to see if your issue was the same as mine?



Big Al

 

[Dominoelover thegamenotthepizza]

Big Al, try this link.

 

[Larry Phillips]

That be the elbow. Big Al, what kind of symptoms are you experiencing? When mine was doing this, the engine ran like crap. The truck bucked at stoplights, idled like it had a racing cam in it, and died at idle, or at stoplights, or when slowing down to turn corners, etc...

 

[Alan Peters]

It bucks in drive and hesitates shifting to third. It idles low around 500 when warm and sounds like its going to die. I cleaned the IAC and throttle body and some change but the shifting issues are still present. Sounds similar to yours. I originally thought it was engine computer related but now wonder if the elbow is the problem.



Big Al

 

[Mike Wilson]

The elbow is ALWAYS the problem, or part of it, on our Tracs!



Rear end clunking? Replace the Elbow...



Front wheel shaking? Replace the Elbow!!!

 

[Richard L]

Larry,

I'm glad you found the leak and got the 2-3 flare fixed, although I don't think it had anything to do with the ECU memory. The computer learns your driving style/preferences by just averaging the last settings with updated settings. so it really only stores a weighted average of your prior settings.



It learns this information ratiher quickly, but if you had a vacuum leak, it has been compensating for that for a long time. It is odd that your ECU did not detect a lean condition and give you a CEL? That's usually the first tip off that there is a problem nwith the infamous cracked elbow.



...Rich

 

[Larry Phillips]

Your right, it should've thrown a CEL, and it was bad enough that I can't believe it didn't. I'm still scratching my head about that one. As far as memory I'm thinking memory in terms of RAM. An EEC, shouldn't be that much differant than any other computer as far as operation, and it's a VERY basic computer designed for this task.



Here's the picture of my cracked elbow that I've been meaning to post.



[Broken External Image]:

 

[Gavin Allan]

Actually, I think the ECU stores a "rolling average" of the readings. If the old data didn't roll off at some point, I think Larry's thought about insufficient RAM might be possible.

 

[Richard L]

Gavin,

I'm not sure what you mean by a rolling average. The ECU can store multiple error codes, but it only stores that last learned settings after averaging them it with the previous readings, so it only stores the last average reading.



I think Rolling average is the same as what I am saying. the old reading and the new reading are averaged together, each counting for 50% of the average.



...Rich

 

[Gypsy me]

wtg Larry!