Chip Tuning for BMW 745i 3.4 L Motronic Engines

Important note dated June 30 2012: I am in a process of completely updating my chip tuning pages in this brand new 745i Chip tuning web. Here will be new stuff and also quite a lot pictures and other material on my fairly comprehensive work rebuilding my 745i-85 Executive. Right now these pages are still just sraigth copy of the old "Kingshill" pages. I am all the time still supplying the tuning chips for 745i models (some 14 different chip versions by now!)

Best regards Jarmo Havulinna

New notes dated October 11 2012: 1. I have added third 745i Motronic box to the tuning chip list: 0 261 200 025 . These boxes have shown up mainly from Japan and Russia. More about this in the new web pages 2. Finally my 745i Executive is getting there after thousands of hours and dollars. Take a glance of the status. Full story will be in the new web pages. Still quite a lot to be done.

The nice thing about 745i tuning is that the user can select many different levels of performance. One does not have to spend a lot of money in order to get started with considerably higher power and torque levels.

The most economical and easiest way to get started is the Motronic Chip Upgrade. In addition you only need a turbo pressure gauge and a simple valve to restrict air flow to the wastegate control hose (do not bleed the hose for higher boost!!!). More detailed information is in the Start-up Kit and Wastegate sections of these web-pages. This is a good way to start and to get the feeling of considerably higher power and torque. In this set up you schould limit the boost to about 0.7-0.8 bar (300-330 hp/450-500 nm). You can install the valve close to the wastegate or into the cockpit (this is recommended as that same valve can then be used with the adjustable wastegate, if you decide to upgrade). The max. full throttle boost in this set up is about 0.6-0.7 bar giving 0-100 km/h acceleration of approx. 6.3-6.5 s., which is already an exellent figure for any automatic sports car. More importantly, the middle range boost is about 0.7-0.9 bar giving tremendous acceleration in the 60-160 km/h speed range.

This modification to the 745 Motronic computer program allows unlimited increase in power and torque. The practical increase is dependent on several other setups in the car and engine. Typical increase is 100-150 hp together with some modification of wastegate or to wastegate's control system. Power levels of 350 - 500+ HP and torque over 640 nm are possible.

There are many ways to increase boost. You can either have a fixed boost level or a adjustable boost control. One of the best boost control systems for 745's was the Tuoma Perfection adjustable wastegate, but that is not available at the moment and may not be manufactured at all anymore.

The standard 745i 3.4 L engine gives 252 HP at 0.3/0.5 bar boost. Engine cutoff is set to 0,7 bar, which many of the 745 owners have unfortunately experienced.

This modification to the computer program removes the cutoff limit and sets all necessary parameters for unlimited power. The program is dynamic, so performance is optimal at any and no boost conditions. Torque is increased also considerably.

As a rule of thumb this program increases power by approx. 50 HP for each 0.2 bar step:
0.7 bar = 300 HP, 0.9 bar = 350 HP, 1.1 bar = 400 HP, 1.3 bar = 450 HP, etc...
The standard 745 turbo is good at least upto 1.5 bar, but we have not calculated or tested it at higher boost levels.

We have not removed the max. RPM limiter. As you can see from the enclosed performance data the max. power is achieved well under 5000 RPM, so there is no need to increase the RPM limit. This is also a safety and reliability factor for the engine. Once the piston speed increases above 16 meters per second special pistons should be used.

The cost for this upgrade is only about one euro or dollar per HP!
You can buy the EPROM with the modified code for € 205 (about $225). The price includes shipping and handling costs to anywhere in the world.

Note that now you can pay with Money Order, PayPal and all major Credit Cards (using our secure PayPal link) as well as with Western Union cash transfer.

The order procedure is simple:

Check which Motronic hardware/software version is in your car. You find instruction in My Motronic?

Recommended site for additional information and discussions about 745i tuning: .