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Discussion Starter · #1 ·
@ the auto to manual guys,

my car runs fine with automatic ecu and manual transmission, except one thing:

When cruising on the autobahn, constant speed (for example 140 or 170kph) and holding this speed for a while (>10min), the car will suddenly slow down for 1-2 seconds. Its rather infrequent, but today it happend 3 times on a 1hour trip. It feels like hitting the rev-limiter, just a bit longer and harder. Or like the transmission gets "stuck" for a second.

Anyone else made that experience?
Maybe that is a function from the AT transmission control?

I can`t imagine, because the ECU input (AT indicator) is wired to Neutral permanently.
 

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Podiatrist
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22,260 Posts
@ the auto to manual guys,

my car runs fine with automatic ecu and manual transmission, except one thing:

When cruising on the autobahn, constant speed (for example 140 or 170kph) and holding this speed for a while (>10min), the car will suddenly slow down for 1-2 seconds. Its rather infrequent, but today it happend 3 times on a 1hour trip. It feels like hitting the rev-limiter, just a bit longer and harder. Or like the transmission gets "stuck" for a second.

Anyone else made that experience?
Maybe that is a function from the AT transmission control?

I can`t imagine, because the ECU input (AT indicator) is wired to Neutral permanently.
The car is governed at around that speed 145mph or so.
You are probably hitting that.
 

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Podiatrist
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He said "140 or 170kph"
Ah. Misread on my part.

It's not a transmission issue. They don't get stuck.
My guess is the throttle body and ECU are doing something tricky. Possibly 02 sensor reading based.
 

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Discussion Starter · #6 ·
Thx for your input,

Yeah, it happend in a speed range of ~80-110mph (140-170kph), constant rpm. Yesterday there was no problem at all driving the same route again (like every week).
First i thought there is an issue on the transmission vent valve (thought i did some damage when the transmission went in) but then i realized that is just an air vent. Perhaps both couldn`t cause a "stuck tranny" :lol:

I also guess it has to do something with the TB, or something like a fuel cut. But it kicks in very hard, so i don`t believe it`s just a faulty (engine) sensor.
If it is an electronical problem, it has to be something from the ECT part of the ECU, maybe because of some inputs which aren`t connected any more.

The car was running great when the AT was in, and 99% of the time it also does very well with the MT.

And seems like i`m not the only one having this trouble
 

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Discussion Starter · #8 ·
any particular reason you didnt want to move to a manual ecu/harness?
Not really... The IS300 was never sold as a 5-speed manual on the european market ...so it is hard to get MT parts and they probably won`t be plug&play (there are also some wiring and electronic differences between Euro and US-models) ...but that wouldn`t be such a problem.

Just wanted to ask if somebody knows to fix the problem without changing the whole engine ECU :)
 
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