TOPIC: 2007 Chevrolet Avalanche ZLT - 75mph ECU reaction

Hi All,

Had an interesting experience on Monday after another experience over the weekend.

Had to go make a run from Tacoma over to Cashmere, Washington which is 150 miles NE over two mountain passes. Most of the route is a 70mph speed limit but occassionaly you have to push a little more up the mountains.

I got it up to 75mph at 2300rpm (automatic trans) and the ECU picked a map selection that put the engine in V4 mode getting 29 mpg. This was repeatable, during the trip I found that there were several different speed/rpm combinations that the ECU reacted to.

Then on I90 going towards Seattle, the ECU decided to throw a code involving a "MAF/MAP correllation error". Sucker did not have a clue what was happening.

Unfortunately the 2007 Avalanche, Suburban and Escalade all have the ECU from Hell in them.

And I think I am correct on this, because the ECU detected something that required it to take control of the engine to reduce speed it accessed a control module used primarily by the Stabilitrak program which detects road slippage and is supposed to correct for it.

When it threw the code it also put up the "Service Stabilitrak" and "Stabilitrak Disabled" messages. Normally this flags the ECU to reduce speed to get the vehicle under control by accessing the Stabilitrak module. This ECU when it detects any kind of condition that requires reducing speed (in its tiny digital mind) it accesses the Stabilitrak module to control the engine.

Then everything goes wrong. Last time I thought the engine was going to fall out onto the Asphalt the way it was shaking, this time at least I was able to pull over before the crap hit the fan, plug in the scanner and clear the code which reset the engine to normal operation.

GM has not admitted to any problem with these ECU's or the Stabilitrak program and this has also happened in newer vehicles with the Stabilitrak installed.

Anyway the cool part I wanted to point out was the 75mph at 29mpg going up a medium grade.

Karl Fortner
Tacoma, Washington

I had something similar happen on a newer Jeep, Karl. In this case, it was showing the same errors, adding a charging system light, and doing this in the driveway during the low-level conditioning process.

With this vehicle, it was a Personal Licensee who had initially placed The Groove too far from the plate to get any real value. He had rotated the plate to 26% before cutting The Groove which moved The Groove about 3/4" too far into the air stream.

After filling in and regrooving was when the errors came. I regrooved it twice before I discovered the source. It was about .003" of epoxy that had found its way between the plate and the body near the axle undetected. Once that had been removed, all codes cleared and the beast became a beauty!

Of course, I know this is different in operational indicators, but the codes appearing for this little issue in the TB is interesting, as the air flow has nothing to do with the charging system, the ABS or traction control.

Just something to make us scratch our heads and go "Hmmmm..."