big acceleration problem Continental GT 2005
 

Bonjour, ce n'est pas un problem facile.

First thing to do is check if the transmission control module (TCM) is wet or the contacts are corroded. Not sure on the Bentley, but on vag vehicles often it is located under the carpet.

Bon chance

Yes the TCM controls the gearbox. Monitors and adjust all the import dada from the various other modules. I'm not sure where it's located. As stated earlier usually under the carpet which means susceptibility to wetness. This would be the first step before going any further.

The transmission control module is inside the transmission itself, attached to the valve body.

The TCM is located in the transmission on a ZF6HP26A61. It is the Mechatronic unit. It has a round data plug/connector and is located on the leftside of the transmission at the pan level.

I'll also suggest you look at your MAFS (especially the main MAF, engine rightside). On P1857, Load signal error, the engine load that the transmission uses for gear shifts comes from the MAF. If the MAF gets lazy/slow or flaky it cannot signal fast enough during downshifts or at its limits. This SOMETIMES is the issue with P1857, but not always.

If you do find the Maf is the issue, it is better to replace both MAFS (leftside and rightside) at the same time.


Back to the TCM, you can see the round connector in this pic below the stamped steel bracket

https://cimg7.ibsrv.net/gimg/www.6sp...576e59b9d5.jpg

Haha...treed me again Johnny....

:D hilarious :D

Good info. Go under the car and make sure the contacts on TCM are good. Apply a little dielectric grease to the contacts .

Start with the easy stuff move on to the more complicated. Indeed lazy MAF sensors can be a contributor.

MAF = Mass Air flow Sensor. There are two. One on each downtube below the air filter boxes and in the air stream to the turbochargers. One is a 5 wire, the other is a 4 wire. On Bentley, the MAF connectors are known to fail too. I had to replace both of my connectors. If a signal wire is intermittently failing on yours, that could possibly be causing the P1857.

This is a pic of one of the two MAFS. Located underneath the air boxes.

https://cimg3.ibsrv.net/gimg/www.6sp...55af8fa2c1.jpg

By 4 minutes! You're just faster at the draw than I am.....LOL

Yes, looking back at your first post. I am guessing when you said new flowmeter those were the MAFS. Are the new parts replacements from an attempt to fix this problem, or did they preempt this failure?

If you're sure the MAFS are good and are confident about the connectors, then there is a possibility that, because you're seeing an ABS warning, there is a speed sensor related issue. The trans TCM is receiving speed inputs along with engine load. These must be in a preset range for any given condition for the TCM to respond to commands such as upshifts and downshifts. If one of the inputs is out of an expected range such as the speed doesn't match with an expected load range, the fault is set.

I did a little researching and in the case of an Audi (with the same VAG power management protocols), the ABS unit needed replacement. Sorry if that is actually your issue.

As Mr. Applebaum suggested, check integrity of all connections. Please include in that, the MAF connectors. In my case, I was getting an intermittent MAF out of calibration, Address 11 (leftside MAF). It turned out to be an intermittent connector failure, a known VAG cars defect. The actual terminal spring ends in the connector fatigue and do not allow enough tension on the spade terminals in the MAF. Here is a pic of my old ones. Maybe if all else fails, and you run out of options, check these, but they're very difficult to diagnose as a static continuity check will show them OK.

https://cimg7.ibsrv.net/gimg/www.6sp...d4e2a05472.jpg
These are my old connectors. The five wire at the top is the failed connector. It is the secondary side/leftside (address 11); the lower one is the four wire from the primary/rightside (address01). I replaced both sides with an upgraded parts replacement.