number_one_c55

Hello everyone, have a bit of a strange issue.

Have a E55 120,000miles, the issue I am experiencing is during an overtake at highway speeds. 5-4 downshift at moderate throttle the car feels like is hesitates and or feels like something in the drive-line is temporarily binding.
Would also be inclined in saying performance doesnt feel the greatest anymore. Car has had some work done to it which I will list below. This is just a recent development.

Couple other symptoms which I will note that may lead me to think it may be a torque converter issue would be, on real cold mornings it feels like the torque converter will not disengage - the car will lug over at 800rpm while driving down my street. Once transmission is warm its not an issue.

I am starting to think the stator in the converter is failing.

I have taken the valvebody apart, done a trans service, nothing really abnormal noticed.

Work Done:
VRP 76MM Pulley
Colder Spark Plugs
K&N Filters
Trans Service
RaceIQ Tune
010 IC Pump
VRP Heat Exchanger

Car performed well in stock form as well as with all the performance modifications up until the last week or so.

ta72

iTrader: (1)

If your maybe thinking about a High stall converter, i have one listed. Upd 3000 high stall. $550 shipped.

number_one_c55

Appreciate the reply but I’m in Canada where our money is on par with Monopoly money in terms of value.

I have a S55 that I’ll part out that May donate it’s converter to the cause.

GinDistiller

Do you have a scan tool? I'd first look at things like fuel trims, rule out an issue with the engine. I had thought possibly I had a torque converter issue as it felt like it was locking up more than it should, but think I have narrowed it down to fueling issues when the car is under heavier load (i.e. the scenarios you outlined), looked at my fuel trims and they are nearing 15% long term which is way out of range. I have newer IAT, front o2s, plugs are not that old, and no specific cylinders are showing as rough (which I would assumed would happen should I have a bad coil pack). Fuel pumps and filters done 2 years ago.

So basically I'm leaning towards a vacuum leak, and that might make sense for you as well if it just showed up out of the blue. If I'm in comfort and give it moderate throttle from a stop, the torque converter slips like it should.

Following to see any updates!

PieRat

Good advice to check fuel trims always wise to keep an eye on them with a elm327 scanner which can be had for very little money and paired with an app on your smart phone.

The tune can be out of whack for LTFT (long term fuel trim) during light throttle or idle. Sometimes when you get email tune it need adjustment so if it's bad try reach out to raceiq for an updated one.

number_one_c55

Hmm interesting, didnt even think about fuel trims. When I first got the car I had an issue where the manifold on drivers side was cracked. Removed it and had it welded up. Wonder if I have an exhaust leak pre primary 02 sensor. Were currently out of town will check once I'm back home with the car.

number_one_c55

Sorry forgot to mention car also has 550cc injectors.

Exotic-metal55

We can make custom stall converters for you to match your power and mods, so that you keep the stall just under peak Torque. With our boosted cars, it is best to have the converter matched to your mods. We have been custom making Converters for the 722.6 for 8 years now. It was one of my favorite mods on my car!