And now it’s time for topical subject – chip tuning. As this blog is dedicated to petrol engines and even till N54/55 BMW manufactured only atmospheric petrol engines, so now – about chip tuning of atmospheric petrol engines.
Chip tuning can have several tasks, but let’s start with most popular (the one, you usually think, when hearing “chip tuning”) – increasing the power (torque) of the engine.
Increasing the power (torque)
Who does not want, that his/her car would drive brisker? And, if this can be done, “only” using the computer and pressing “several buttons”?
Unfortunately, the possibilities to increase the power (torque) of atmospheric petrol engines are very, very limited. The reason? The air, sucked in cylinders (accordingly – the air, which can be used to burn the fuel) is in such amount, how much can flow in via inlet manifold, and it’s not possible to increase this amount only via computer. The throttle is completely open in kick-down mode – it’s not possible to make it “wider”.
At the expense of what the power can be increased, and what is the benefit?
Chip-tuning companies are promising the increase of power for several (to 5) % for atmospheric petrol engines. This increase is reached by:
- earlier ignition and larger allowed detonation. Both parameters I merged into one section because they are directly connected. Using high-quality petrol (with higher octane number, for example, E98), the ignition advance angle can be increased (light up the fuel mixture earlier – for burning process to start to work closer to top/0 point of the cylinder) and to increase the efficiency of fuel burning. Unfortunately, the consequences are well known – detonation (avalanche-type fuel burning process) – this vibration damages the engine. Allowing “harder” burning of the petrol, several % of power is gained, at the same time shortening the work life of the engine. Moreover, if for M series engines the manufacturer left higher possibility of “tuning”, then for N series engines – DME not only takes action (delays the moment of ignition) in situation, when it detects significant detonation, but the virtual “fuel quality” is measured non-stop, when working much closer to the detonation threshold (it means, the engine “adapts” accordingly the petrol filled). Because of this reason, the real benefit of chip tuning of N series atmospheric petrol engines will be tiny;
- forcing the engine to work with the enriched fuel mixture. The idea is simple: in kick-down mode, the fuel mixture in cylinders is made richer. Yes, part of fuel amount will not burn, but the total consumption of air, present in the fuel mixture, will be guaranteed. Additional bonus – cylinders will be cooled much better, the threat of detonation will be decreased. Unfortunately, also, in this case, the increase of power is close to 0. Already till chip tuning of a third person (it means, leaving the factory), the BMW engines are working in a kick-down mode with Lambda till 0.80, which means – the mixture shortly is very rich, and additional fuel will not give any benefit;
- more efficient usage of the engine’s auxiliary systems (for example, VANOS). Unfortunately, for more efficient use of VANOS (one of the main problems – when the car accelerates, the performance of this system differs from static performance mode), very complicated measurements on Dyno stand are required – usually, for stage 1 (most simple – typical) such operation is not performed;
- increasing the max RPM. Without replacement of certain engine parts (valve springs, etc.), such tuning can lead to damages of valves and pistons of the engine, when they “meat”. Additionally, this “improvement” doesn’t increase the torque of the engine, just allows to torture it by higher RPM.
There, using all, mentioned in first two points, “as if” the increase of torque and power for several % is gained. Will the user feel it (the increase)? Of course, no!
Can this increase be measured by Dyno stand? Actually, it’s quite cumbersome.
Here is an excellent entry:
In this entry, the guys are checking the relative changes in readings of the stand (exactly what we are interested in – changes “before/after”). As we see, many factors (tire pressure, the tension of fixing cables, the flow of cooling air) are giving similar changes like a benefit of the chip tuning! It means – the measured benefit of chip tuning is VERY dependable of measuring conditions.
People, who learned physics, will say – measurements of power have to be repeated for several times, sequentially modifying the software: ”old/new/old/new”, etc, not changing the conditions of measuring!
Yes, they are right, but… This also is not possible, because we have to give time for the engine to create new adaptations (it has to be driven within several conditions) – both fuel mixture, knock sensors, etc. Unfortunately, such “driving” cannot be performed on Dyno stand, because (air flow, resistance) conditions are strongly different from real life condition. In turn, if the car will drive for a longer time, creating adaptations, the principle of quick comparison “old/new” will be disrupted.
With this I wanted to say, that, unfortunately, such small (several %) increases of power/torque is not possible to measure correctly with equipment, usually available for chip tuning companies. The results are not plausible, because the engine is not adapted correctly (if the measurement is performed directly after chip tuning).
How the chip tuning companies reach “more impressive” results?
First – better result “on the paper”. Simple, but efficient way: in measurements after increasing the power, indicate smaller calculated losses of car’s rolling part (gearbox, differential, etc.). Or, for example, other temperature, air (atmospheric) pressure – simply “cheat” a little. Using such techniques, we can get missing percents in the graphic (if the measuring doesn’t succeed directly after performing the chip tuning).
Second – better “boost”: the changed reaction of DME to the position of the accelerator pedal. Simply saying – the “active zone” of the accelerator pedal is compressed in the starting part of the accelerator pedal movement. Accordingly – pressing the pedal for 10%, previously DME considered, that the pedal position is 10%, but after “tuning” – that the pedal is pressed for already 20%. In such way as if the more aggressive performance of the car is reached, feels like more power. Of course, nothing has changed in kick-down mode, but in the first moment, when you receive the “tuned” car – wooow, it feels like real boost! Yes, later you will discover, that it’s very hard to drive comfortably in the city, but somebody will oppose – “the car now has so much power, that even the lightest touch of the accelerator pedal makes it scud”. Of course, it’s just an illusion.
Short summary – for N series engines, the chip tuning of the atmospheric petrol engines has a very little effect – close to 0. But – there is one exception.
N53B30U0 (160 kW version) is first/only BMW E series engine, which has concept “power class” (later popular for F series petrol turbo engines).
N53B30U0 (160 kW) has following differences from N53B30O0 (200 kW): inlet manifold without DISA (200 kW version has 2 DISA valves) and other software of the DME. For 160 kW version, the DME software:
- don’t perform management of DISA valves (they are not intended);
- don’t open the throttle in full in kick-down mode;
- in kick-down mode Lambda stays close to 1.00.
It makes sense to perform the chip tuning for N53B30U0 to increase the torque. Performing the chip tuning, DME software is commanded to fully open the throttle and create enriched (max power) fuel mixture in kick-down mode. Yes, the effect can be felt (several chip tuning companies promise the increase of torque from 270 to 300 .. 310 Nm; an increase of power from 220 hp to 240 .. 250 hp), but the result subjectively significantly lags behind the 200 kW (272 hp) version.
If you want to get full power from your 160 kW version, the shortest way – engine rebuild to full 200 kW version! The benefit is impressive!
The other types of chip tuning
In parallel to the power increase, the chip tuning can have also other tasks. For example:
1. Switching off the control probes (control of the performance of catalytic converters).
This “improvement” was topical for older M series engines. If the vehicle had to correspond exhaust norms of Euro 2, the control of the CO catalytic converters could be turned off (to avoid the error messages regarding the performance of CO catalytic converters). Unfortunately, also from such type of updates, I have seen NONE, which would be done correctly. I’ve seen scenarios, when after the “improvement”, DME continued diligently to heat up (non existing) CO catalytic converters (and increased fuel consumption due to insufficient performance of CO catalytic converters); there were also scenarios, when even the control probes are heated (obviously, just the appropriate error messages were deleted from error message map). Cars with N series engines have to correspond to norms of Euro 4, which means – CO catalytic converters have to perform their task in reality, and this “improvement” part (I’m only glad of it) is not topical. Needless to say, that regular chip tuning “specialist” had heard nothing about the topic, that the control probes are also performing trim of the wideband probes – it’s a good thing, that for these engines the “switching off” the control probes is not topical. It would increase the amount of incorrectly performing engines.
2. Programming off the EGR.
There is myth between car users (not even taking in account, what brand of car or fuel type they are driving): the ”bad” EGR valve collects fuel dirt and oil leftovers from the exhaust, the EGR valve itself is contaminated with them, the power of the engine is decreased, the fuel consumption increases – it only does evil! And that’s all – in the name of ecology! So, several chip tuning companies are offering a service – turn off the EGR valve.
I say – this “improvement” only does bad to the engine.
- I’ve seen many engines with mileage of 200 .. 400.000 or even more km, for which the EGR or inlet manifold never been cleaned, but – they are clean, no cleaning necessary. So how about carbon residues, you will ask? Actually, ususlly they are not carbon residues, but oil burn! How the oil got into the inlet and also exhaust? In the inlet, oil gets due to damaged CCVV valve! In the exhaust – also, if the seals of the valves are damaged, or the piston group is worn out. The first conclusion – if the engine is in normal (not even talking about good – the no such problem would be present) technical condition, CCVV valve – works, EGR and the inlet manifold will have no problems with residues!
- correctly working EGR reduces fuel consumption! How? By partial load, the EGR is opened, and cylinders are filled with a mixture of air + exhaust gasses. Replacing the air with non-burning mixture (exhaust gasses), DME can open a throttle for more amount and in the same time – reduce the air shortage in the inlet manifold: reduce pumping losses. The same, what the Valvetronic and Stratified charge do. Valvetronic/Stratified + EGR = even more economical car!
- using EGR, the exhaust is heated much quicker, and again – the fuel is saved! While the CO catalytic converters are not heated up (temperature sensors and control probes don’t confirm their correct performance), the VANOS of exhaust is in position, which forcibly heats up CO catalytic converters (but the efficiency of the engine is lost), the fuel mixture can be enriched (Lambda around 0.98). EGR reduces the amount of fuel, which is used, to heat up the CO catalytic converters.
And in addition to all – EGR ensures a longer lifetime for:
- spark plugs, ignition coils. If EGR works, as it’s supposed to, the temperature in burning camera is optimal, the spark plugs are self-cleaning. Instead, if the spark plugs are not self-cleaning – they are clogging, the load to ignition coils increased – their lifetime is reduced. Additionally, of course, if the spark plugs are working in inappropriate conditions, the engine will start to shiver sooner or later (misfires will appear);
- the exhaust system, CO catalytic converters. Only when the exhaust system is heated to an optimal temperature, it will work correctly. If the temperature is too low, the exhaust system is quickly clogged with oil products, sulfur. The turning-off the EGR is a most efficient way to damage the exhaust system.
If your car has problems with contamination of EGR or inlet valve, solve the cause, not fight with consequences! Damaged CCVV will continue to contaminate the inlet manifold and damage the exhaust system also after switching-off the EGR! Switching-off the EGR will only make the situation worse – the damaging process of the exhaust systems speeds up. Switching-off the EGR has NO positive effect!
Additionally – correct deprogramming of the EGR for N series engines is not possible! EGR affects many (several tenths) of management and adaptation maps, which means – programming off the EGR, fundamental changes have to be done also in many important management maps (for example: throttle/Valvetronic; air mass meter; ignition angle; fuel mixture/Lambda, etc.). Of course, no one is doing that, and as a result – the engine works in incorrect modes; shivering and other side effects – guaranteed! My experience only confirms everything, as mentioned before. I’ve seen the adaptations, which are performed for “deprogrammed” EGR (how the non-existing component can perform adaptations?), and never-ending problems with shivering engine. After such “improvements”, the car owners invest several thousands of EUR in the repair of the engine (replacing injectors, ignition coils, spark plugs, etc) without success!
And, when finishing the topic about EGR: no, it doesn’t decrease the max power/torque of the engine, because in case of large inquired torque it is… completely closed! It means, its affect is 0!
3. At last – the “deprogramming” of the NOx sensor for the N43/53 series engine.
Yes, everyone, who has learned, how to read the configuration of ECU with NCS, has noticed, that DME of MSD80/81 has checkbox “NOx sensor”. So the “most knowledgeable” chip tuners are ready to “code”, it means, “turn off” this sensor. Unfortunately, such “turning off” is equivalent to the situation, when/if the sensor is damaged. Such “tuning” is characteristic with:
- the engine switches off the Stratified charge, the fuel consumption grows;
- the engine doesn’t perform cylinders individual adaptations, increased vibration is observed, increased CO/HC (problem to pass TI);
- usually the error messages regarding fuel trim, Lambda probe trim, misfires are following (the period of replacing the injectors starts – without success);
- the NOx catalytic converter is damaged (its desulphation is not performed), CO catalytic converters are damaged (due to an inappropriate temperature of the exhaust system).
And finally – one nuance, which has to be taken in account, when performing “improvement” of any type – after such “chip tuning” there will be no possibility to correctly update the software! It is very important especially for N43/N53 series engines, which initial software releases of DME had many fails (which lead to shivering of the engine).
Even more – mostly these chip tuning companies are using old (initial) versions of DME software as a template, which means – after such interference: the engine will work incorrectly even if all components will be in perfect technical order. I receive many complaints, in which is mentioned – after “chip tuning” (especially typical, when rebuilding N53B30U0 to O0 version – not replacing the FR of the car, and after “deprogramming” of EGR or NOx sensor) the performance of the engine is unsatisfactory, but – there is even no possibility to increase the Integration level of the car.