Engine remapping

[garymac]

I was speaking to an independant about my C250 turbo diesel and he suggested, at a cost of approx £400, that the engine be remapped.

I was basically told that after remapping there would be more power, but is this the only advantage?

How does this remapping thing work?

 

[Shude]

How does this remapping thing work?

The ECU is programmed from the factory to take into account petrol, oil and air quality, service schedules, emissions, performance and consumption.

If you are willing to use the best oils, the best fuels and service the vehicle regularly then some of the engine software parameters can be adjusted to make the margins slimmer and squeeze a little more performance and possibly a little less fuel consumption out of the engine.

TD engines benefit from software tuning more than some others simply because the turbo settings can be adjusted and these give big gains in power/performance.

 

[Richard W]

Basically as Shude has said the engine is de-tuned by the manufacturer to take into account the variety of fuels available in the world, the emissions regulations and so on. Because they take the lowest common denominator when doing this there is quite a large 'tolerance' level built-in to many of the boost and fuelling parameters. The well regarded tuners will amend some of the fuel and boost 'maps' in your car to take account of those tolerences and subsequently release more power that the engine is quite capable of delivering.

Just to expand a little further a map is a table of values for a particular function that tells the engine what to do for a specific load/rpm level. So for example - if the throttle is wide open and the revs are at 2500 then inject a given amount of fuel to continue the acceleration to the next point on the map which moght be 2550rpm and so on. There are quite a few maps to take account of different scenarios such as light throttle, cruising etc and for when there isn't a map the ECU can guess a value in between.

Most re-maps are safe in that they don't put the engine under too much stress. If they did then the built-in 'alarm' systems would put the engine into 'safe' mode. i.e. low boost to enable you to get to a garage. There are examples of tuners who do stretch things and reach those limits which can be frustrating, but you'll find that most of the reputable guys don't have any issues.

Be aware that any re-map will invalidate a manufacturers warranty and you may have to revert to their own warranty if a problem does arise.

 

[garymac]

Thanks for that - cleared that one up

 

[Dieselman]

Be aware that the mapping/chipping causes the ECY to inject more fuel, which in turn will cause the combustion temperatures to rise dramatically.

Fuel quality for a diesel engine is not the reason manufacturers leave a tollerance, it is more to do with engine logevity and exhaust gas temperature. This may not be an issue if you never drive up long steep hills laden or tow but it could be.

Before fiting a chip I would want to know what the EGT temperatures are as if they are too high serious damage may ensue.

 

[Richard W]

Before fiting a chip I would want to know what the EGT temperatures are as if they are too high serious damage may ensue.

True the EGT will rise, and it's definitely something to consider but the more reputable tuners do give warranties and I'm sure that they will have done some research to make sure the whole tuning package works well and doesn't affect engine longevity too much. The E60 has different tuning packages dependant on the fitment of a particle filter - that's the lengths that these guys go to to make sure their products are suitable for long term use - after all if they were likely to suffer from massive warranty issues I'm sure they simply wouldn't sell them.

I'm fairly certain that if things were outside the tolerances too much then either the engine's own sensors would restrict things to bring temperatures back down or it would simply go into 'safe' mode.

I know of tuned diesels that have done 150k+ without any ill-effects. (mine's done 105k miles...... )

The crucial thing is don't try and save money by buying from some no-name tuner on eBay - it's worth researching and making sure it's a reputable company with decent warranty backup and a good heritage - Superchips, Revo, DMS, Alpin spring to mind.

 

[R2D2]

I Superchipped my C200 and had no bother at all. HTH

 

[Dieselman]

I Superchipped my C200 and had no bother at all. HTH

That's because it didn't do anything but advance the timing a bit.

Diesel tuning injects more fuel so temperatures rise considerably.

 

[Dunx]

I think my car ('97 T210 E300TD) was chipped by a previous owner (I presume) as there was a bhp test printout from Well Lane Turbo Centre(??) in the glove box that showed a peak of 208bhp @ 4853rpm. Max torque is around 290 @ 3000 rpm when I bought it. I thought the max output of the 606.962 engine was around 170bhp.

I have a couple of questions regarding this...

1. Is it possible to return the car to a pre-mapped state?
2. Should there be a rev limiter, as I have been able to rev the engine to around 5200rpm (briefly) under load without hitting any limiter?

TIA

Duncan

 

[Dieselman]

The E300 TD should produce 177Bhp in standard form.

The 208 figure is a typical chipped figure.

Your car was hitting the governor at 5200rpm. You won't feel it as it just backs the fuelling off to hold those revs, unlike a petrol engine tends to cut the fuel so becomes jerky.