SSSquid Tuning custom M60B40 chip about to install

[Legoman]

I have just purchased a custom chip for my M60B40 from SSSquid Tuning and was wondering if anyone has already done this and can perhaps give me their opinion?

The chip I have ordered is a custom job to fulfil my particular esoteric requests rather than the standard job from his website, but nevertheless, it should be roughly comparable to a standard stage 0.5 tune if anyone else is running that in their M60B40?

I wasn't particularly looking for any great increases in power/torque, rather my #1 priority for wanting a custom chip was to get rid of the DFCO code that shuts down the injectors on closed throttle overrun. I don't like the hard step from idle speed powered drive to full-on compression engine braking when trying to drive slowly on the cusp of a closed throttle. It makes for undignified and unpleasant driveline shunting and transmission backlash wear with the constant back and forth between going too fast and going too slow with no happy middle ground possible without force holding low gears. As such, SSSquid has made me a custom chip which does away with the DFCO by moving its action way up the rev range where it will never be noticed, stage 0.5 mild tune for stock engines, 95 RON/91 AKI fuel use and retaining the stock 6,500rpm rev limit.

Just wondering if anyone else with an M60B40 has tried the SSSquid chip and can report on whether they noticed any difference? I'm not expecting miracles and to be honest will be perfectly happy if just the DFCO code has been disabled.

[Legoman]

Thought I'd answer my own question since no-one else has obviously tried this chip before. I've installed a DFCO disabled custom chip in my E32 740iL's M60B40 today and taken her for a long test drive. No other changes at all. Nothing. Completely bog stock engine. This car is exactly as she rolled off the production line with the only change being the wheels + tyres as you can see from the photo. For reasons of tyre availability it was necessary to make a change to 16" from the OE 15" and so I did this as close to factory spec as possible by putting E38 wheels on. The rubber is Continental which is also what the car came with brand new. So this is probably the closest, most unmolested original specification E32 740iL you'll ever come across. Even the rear SLS suspension still works without leaks and has not been converted to standard shocks. You would be hard pressed to find a more perfect test bed to do a before/after comparison between a stock BMW chip and a modded chip than this car.

The car's 26 years old and it has never been easier or driven smoother than it does now. Absolutely incredible. Right from the get go straight from first fire up after installation it was instantly obvious things were going to be much better. The idle is sewing machine smooth.

The DFCO is gone completely too. I actually have to adjust my driving style a bit now because it's just so much easier, I don't have to be so gentle and careful with my throttle movements to try and drive around the problems caused by the standard tune. If I want now, I can be a binary footed, ham fisted rock-ape with the mind of a rabid babboon in driving style and the car will just take it all in and smooth out my worst efforts at throttle control and make me look like a hero chauffeur instead. It really is that good.

I can't say there's a lot more power or torque, because this is the mildest version tune for this bog stock engine, so that's to be expected, but the car is definitely more enthusiastic and willing at any speed. I'd say there's just enough more power/torque to bring the car's performance back to what it was with the lightweight 15" style 5 wheels it had before I loaded it up with the very heavy Style 61 E38 wheels with Continental SSR run-flat tyres she has now. There was a noticeable dulling of performance when I did this wheel/tyre swap, and that has now been counteracted again with this chip.

So outright performance was never the goal here and for sure it's not going to frighten anyone or worry your Ashley & Martin, but the increase in smoothness is very welcome indeed. As an added bonus fuel consumption is well down now that there isn't big dumps of fuel going into it each time the injectors are switched back on again after a DFCO interruption. Fuel consumption on the stock chip began with a 13 and got dangerously close to 14. It now begins comfortably with an 11 and down the freeway this afternoon, I saw 9.7 l/100km

I have never, ever seen a single digit fuel consumption figure on this car before. It really is so different that an adjustment of thinking about what you do with your right foot is required. I don't need to be anywhere near as careful and tentative now as I had to be before trying to avoid the DFCO cutting in.

If interested, this procedure is exactly what I did to swap the chip.

[CamE32]

Can you elaborate on what DFCO does?

[Legoman]

Can you elaborate on what DFCO does?

Sure, happy to. It stands for Deceleration Fuel Cut-Off. I'm not claiming that to be an 'official' designation for it, it's just what it was referred to as being on a very early 90's chip I had for one of my cars that disabled it and advertised that feature as being one of its selling points in accompanying paperwork/brochure.

It's that part of the ECU programming that switches off your fuel injectors completely when you're coasting with your foot off the accelerator whilst the engine is still being driven by the rear wheels connected through the transmission. This can either be for a long time such as descending a long downhill mountain road or for a very short time such as rolling up to a red traffic light intersection. As the engine approaches normal idle speed, the injectors are switched back on again to prevent a stall.

This behaviour does a few things. It saves a bit of fuel to make the consumption figures a little bit better because when the injectors are switched off, the engine is using no fuel at all. By using no fuel, it also saves a bit of exhaust gas emissions, which makes legislators happy. Thirdly it increases the amount of engine braking available because it effectively converts the engine from being an engine into becoming a positive displacement reciprocating piston air pump driven by the rear wheels. Think exhaust brake on a large truck. All of these are good things. Nobody will argue against lower fuel use and lower exhaust emissions (at least I would hope not). Greater engine braking is also good because when your car is connected to a ZF 5HP30 programmed to shift up to the tallest gears as quickly as possible and hang on to them for as long as possible too, there is pretty much bugger-all engine braking in overdrive 5th gear anyway.

Unfortunately there's a price to pay for all this goodness (there's always a price to pay) and that is it creates constant back and forth driveline snatching and shunting when needing to drive right on the cusp of having the throttle cracked open or closed by constantly converting the engine between being an engine and becoming an air pump. This wears out all the joints and couplings in your transmission and helps to create backlash in your expensive gearbox's gearing. It also may make your passenger's head bob backwards & forwards and makes your econometer needle in the bottom third of your speedometer gauge swing about wildly from one end to the other.

If you are lucky enough to live in one of the shrinking parts of the world where there isn't a set of traffic lights every 300m, where there isn't massive traffic congestion and where the speed limits aren't seriously being looked at getting lowered to 30km/h by the local authorities, then you probably never find yourself having to drive constantly for long periods of time right on the very cusp of the throttle being cracked open the width of a tally-ho fag paper and then slammed shut again straight after for fear of triggering the next speed camera. If this is the case for you, then you will in all likelihood never be annoyed by the intervention of the DFCO enough to bother looking into fixing it. Unfortunately for me, I live in a place where all of these driving conditions exist almost all of the time. Driving a car that was conceived and designed in the 1980's for the prevailing driving conditions of that time in a country with unlimited speed limits where the car competes against domestic airlines for passenger travel options, does not translate well into 2018 with 30km/h speed limits and speed cameras at every single traffic light intersection.

The DFCO is thus effectively a very early attempt at a stop/start solution of engine management to reduce both fuel use + exhaust emissions. The technology didn't exist back in the E32's time to actually have a proper stop/start system such as is common today in lots of modern cars (thank god). The DFCO was about as close as they could get. In terms of fuel use, it effectively does 'stop' the engine while coasting by converting it into an air pump instead. Unfortunately it does this at the expense of driveability, smoothness and refinement.

Even if you can't feel the intervention of the DFCO through the driver's seat via the driveline shunting, you can watch it happening with your eyes via the swinging needle of the econometer in the bottom third of your speedometer gauge. Get the car up to speed or drive to the top of an incline with the gear lever in 'D'+Economy mode, then take your foot off the accelerator and coast while watching the econometer needle. The needle will swing wildly to the left and completely disappear altogether behind the black face plate of the instrument cluster. This is telling you the DFCO is active, your engine has now become an air pump driven by the rear wheels, the injectors are switched off entirely and you're burning precisely zero fuel. In terms of l/100km economy, the milage is now instantaneously zero l/100km. In terms of mpg, your economy is now infinite mpg or ∞ mpg. This is the exact opposite of sitting with the engine idling and your foot on the brake. In that condition the milage is ∞ l/100km or zero mpg.

With a chip that disables the DFCO, the engine runs as carburettor engines ran back in the days before Motronic engine control. ie. the engine will always get at least idle fuel no matter what. This means the engine always remains an engine and never becomes exclusively only an air pump. There is still engine braking available of course, just as there was in automatics with carburettors and fuel injection before DFCO code implementation, because idle fuel is nowhere near enough to cancel out all compression engine braking, however there is slightly (almost imperceptibly) less. In theory at least, fuel consumption will also slightly increase since the engine is now wasting idle fuel on overrun. In reality however I can report the chip I'm using has actually improved average fuel consumption from 13.8 l/100km (17 US mpg) to 12.6 l/100km (18.7 US mpg). I attribute this improvement to the more efficient tuning of the chip as a whole more than counteracting the effect of disabling the DFCO.

It's worth noting that the published average fuel consumption figure for my car according to the owner's manual should be 11.9 l/100km (23.74 US mpg), which comprises an average of driving at 120km/h and an 'urban driving pattern'. In my case where I live, I can never, ever under any circumstances do 120km/h. I would be fined off the Earth, my car confiscated for 'hoon driving', impounded and possibly crushed while I am forced for watch. The maxmium speed limit here is 100km/h and it is very strictly enforced by robo-cameras everywhere. The suburban speed limit here is 50km/h (31mph) and if you try to squeeze that up to 60, you will again be fined off the Earth. There is a current push here to reduce this deadly 50km/h down to 30km/h. The published 'normal' fuel consumption figure for my car in an all-urban driving environment is supposed to be 17.5 l/100km (14.9 US mpg). I have never seen fuel consumption that high, not even while towing a trailer, so I consider my real world figure of 12.6 l/100 (18.7 US mpg) considering the artifical road and legislative conditions I have to drive it, actually pretty good.

I hope that made sense.

[unity]

I actually like the feature. Since it disengages at lower speeds its not an issue around town for me. And when I drive very hilly terrain, its nice on downhill runs. I have a 7 though, maybe the V12 handles the cut-off a little more smoother too combined with the massive weight of the vehicle. It reminds me of the Benz I once had (91 560SEL), it had a "sensor" in the transmission that would basically give engine braking when going down hills. Quote from Wiki: "...topographical sensor that monitored the vehicle's position (whether on an incline or decline) and gas pedal position. The result was an extraordinary capacity to "hold back" acceleration when coasting downhill and to maintain the S-Class' position without using the brake pedal after coming to a complete stop on a steep incline."

[Cactuar]

Great read. Is that feature also on the 735's?

Envoyé de mon SM-T700 en utilisant Tapatalk

[Legoman]

I actually like the feature. Since it disengages at lower speeds its not an issue around town for me.

Unfortunately for me, the speed limits where I live are so low and the gearing in the car so high (to be able to do 240km/h on an autobahn), the reality is that in 2018 I am constantly driving right at that lower speed where the DFCO is on the cusp of disengaging. With the DFCO active, there is enough engine braking that you immediately start going too slow and dropping below the already pathetic speed limit, so you crack the throttle open and then immediately you're now going too fast and will have your photo taken for the fine. There is no happy middle ground where you can make the car just maintain one slow speed constantly. The only way of doing so, is to force hold a lower gear to make the engine rev high so then you can keep your foot on the throttle all the time. But doing this defeats the whole fuel saving aim of the DFCO code and also defeats the purpose of owning an automatic car to begin with. Unfortunately with the early implementation of the DFCO code in old BMWs, the effect is completely binary. The injectors are either all on or they're all off and switching between the two is not ramped in any way. It's a vertical step. ON-OFF-ON-OFF. There is no such thing as half on, half off, or progressively on followed by progressively off.

And when I drive very hilly terrain, its nice on downhill runs. I have a 7 though, maybe the V12 handles the cut-off a little more smoother too combined with the massive weight of the vehicle.

Actually the M60B40 is heavier than the M70 V12 (175kg vs 155kg) and we have the same 100l fuel tank too. I also have the double-glazed windows and most (but not all) of the luxury electrical gizmos of the V12. With the new chip, I now have closer to 298bhp which compares fairly well with the V12's 300, so by most metrics, you'd have to say the two cars are fairly well comparable. I don't think number of cylinders comes into it because they don't behave the same way as a flywheel does. Certainly there is more rotating mass when the engine is being an engine, however the same is true when it becomes an air pump. It's more of engine when being an engine, however it's also more of an air pump too when the injectors are switched off. In theory at least, this fact could make the step even worse and more noticeable in a V12 than it is in my V8.

I don't have much in the way of hilly terrain where I live, however I did take the car yesterday afternoon on a 90min drive up into the hills behind the city specifically for the purpose of coasting down the longest hill we have access to. It's by no means anything to write home about, but it is steep enough to have a weighbridge for trucks at the top, a 40km/h speed limit for vehicles exceeding 22.5 gross tonnes and an arrestor bed for vehicles at the bottom that have suffered brake failure. The normal speed limit is 80km/h. I wanted to test the amount of engine braking still available even with the DFCO effect disabled. I was happy to find the engine braking is still as effective as before and for all intents and purposes unnoticeably different. The car was able to maintain a steady 80km/h with no pedal use at all except for two steeper than average sections where a little bit of brake was needed to avoid an overspeed up to 90. These same two sections however also require a touch of brake in any other car too, whether it be manual or auto, DFCO enabled or disabled, so really and truly, there's no difference.

[Legoman]

Great read. Is that feature also on the 735's?

I'm afraid so yes. It's on all Motronic controlled BMWs regardless of model right from the earliest E28 through to everything in your dealership window right now including all the ///M models. I don't know about the motorcycles and I have no personal experience of models before E28, so I can't comment there.

I have heard that there are some special-purpose cars that can be ordered with a number of modifications from standard to suit their jobs. Things like hearses, ambulances, heads of state vehicles, security limousines etc. which come with all sorts of things like special low speed camshafts, extra exhaust mufflers, special suspension, deactivated nanny-nag warning chimes for things like seat belts etc. and also have the DFCO code adjusted to prevent activation at slow speed.

You can imagine that having your funeral hearse unable to keep perfect pace with the procession of mourners up to the steps of Westminster Abbey for the burial of a monarch and then having it go ding, ding, ding, ding constantly as the doors were held open by the footmen, would not go down well. Unfortunately, where I live the prevailing speed limits are a lot like a funeral procession.