Changing gear ratio

[Cutac]

Hello,

I've done some tinkering on the VTS and lost cruise control in fifth gear.
I've put a bit longer fifth gear to keep RPM's lower(~700), but now the BSI calculations are wrong so it won't engage cruise control in fifth(will in fourth).

Can gear ratio for fifth gear be changed using Diagbox?

[GiveMeABreak]

I don't think so - the BSI and the Engine ECU have independent control over the cruise and speed limiter functions - but work together to exchange info.

It's active from 40 kmh and 4th gear on a manual - and takes data from the ESP system too - so I think the parameters are programmed in and are pretty much set up as defaults and can't be changed for safety reasons.

[xantia_v6]

I did wonder if changing the gear ratio would kill the cruise operation, now we know.

The relevant constant is probably programmed into the engine ECU, maybe an ECU repair or chip-tuning company could adjust it, but it probably wouldn't be cheap.

[Paul-R]

It may also be an engine speed thing. The engine ECU may not allow CC if the engine isn't going fast enough.

[Cutac]

According to this, it can be done. I'll try to find the option in the Diagbox and if there is none, I'll call a renowned Croatian chip tuner for help.
https://www.etuners.gr/peugeot-207-rcgt ... ion-guide/

Engine is spinning fast enough, 2500 at 100 kph, 5000 at 200 and so on until 226

[GiveMeABreak]

There you go then - you'll have to get a chip tuner to do it - as it won't be a Diagbox option. Seems easy enough to do though looking at those pics

[EDC5]

That's a really nice mod to make to a car. I've always thought that most cars could do with a longer top gear!

[Cutac]

Yeah, seems like it's a few clicks and a few numbers.

Yup, and especially if you've done the calculations. Did some thorough calculating to find the best ratio, found it as 0.69 instead of factory 0.86, found the needed cogs in a HDi gearbox, swapped it and voila!
Top speed is barely impacted(weather has a greater impact), fifth gear acceleration is slower, but car is much quieter on the highway. In spirited driving I never, ever exceed fourth gear so fun factor is not hurt.
It's just that I've lost CC and between 60 and 80 kph there's a gap. 70 is a bit too high for fourth(around 2600 rpm), too low for fifth(around 2000 rpm), but I manage.

[Cutac]

Dug through Dbox, didn't find anything. There is a menu inside ECU which says is for when fitting a new ECU. That I don't dare to open .
Anyone ever opened that?

[GiveMeABreak]

Wise move - that's for coding a new engine ECU to the BSI!