It seemed to slip in by the back door a decade or two ago didn`t it? not really noticed as state control as the focus was on the technological problems caused by emission regulations.
Bottom line though is that the state seems to have introduced a severe control over a drivers civil liberties.
Hard to believe that `safe mode` has to be so severe, from an engine preservation perspective.
I suppose though, if any more power were available in safe mode, some drivers would not get it fixed and just continue to drive it under reduced power.
It just seems to be accepted that it`s `normal` to have cars that drop to a fraction of their normal power when a problem occurs with the emission system, with all the risk that entails in the outer lane of a motorway for example.
Is it really true that an engine and systems are not robust enough to default to a stored map giving for example 75% power for a few minutes before dropping further in order to get safely out of harms way?
I`m not convinced that driver safety is getting first priority with these systems.
What are your views?
Edited by oilrag on 15/09/2008 at 10:01
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Better than cutting out completely?
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Yes. But I just feel we have all `taken the King`s shilling` with these systems. Given the computer processing power that`s available now, I just expect better.
A microscopic speck of dirt on the MAF and its as though Atilla the Hun has just rammed a large kebab down the inlet manifold.
Does a tiny speck of dirt on the MAF justify a full, instant, no warning, belly-flop in the outer lane? On the one hand, these systems are blamed for being far too complex, but on the other there seems to be one level of catastrophic response regardless of the severity (or minor nature) of the problem.
Edited by oilrag on 15/09/2008 at 12:24
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My Mondeo once went into "limp mode", less boost, needed an injector reprogrammed.
My previous such experience was a Vectra that when ino back-up mode due to a crank sensor failing, it apparently reverted to using a cam sensor instead, set itself a 1200rpm idle and a rev limit of 4500rpm, I thought it was quite clever, the alternative would be to be stranded or have another 2.5 ltr 24v V6 in the boot ready to burst into life in an instant.
EDIT: IIRC it was in fact my 2.0 SRi that suffered the cam sensor failure, the V6 was (relatively) trouble free.
Edited by cheddar on 15/09/2008 at 12:34
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That does sound clever Cheddar.
Mine settled for 40mph max on the Motorway near Leeds
;)
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Is paranoia taking over completely?
I am quite sure that it is up to the vehicle manufacturer as to the level of power available in 'limp home' mode - and it probably differs according to the fault detected. There is no 'state control' here.
Presumably the manufacturer programs the ECU so that the potential for damage to other engine components (e.g. to a catalyst) is limited.
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Understand your comparison with ''the Kings shilling'' there OR, simple answer, don't buy the modern junk, mind you that seems to be the situation at the moment anyway.
Many car buyers like all this gadgetry, they seem convinced that they need auto wipers and headlights and automatic climate control, isn't all so lovely, what i wonder is how we managed to stop or control our cars before electronic brake assist and a myriad of anti yaw (whatever that may be, the Tornado probably had it) and ASR/EBS and the like half of which i have no idea the meaning or use of, and certainly do not want, nor likely to buy either.
4x4 drivers who couldn't possibly mount the kerb at Aldi, probably involuntarily, without hill descent control, the whole caboodle is frankly laughable.
Did you know its now apparently fashionable to shop at Aldi or Lidl, they didn't have the common sense to go there before some guru told them to, and they let these people vote, thats why the same crew keep getting in then..;)
5 years later its all going wrong, and they then find no one wants to buy their complicated automatic everything machine, so to compound the folly they go out and buy another even more complicated, and change makes too because the advert/Clarkson or similar told them it was the bees knees.
I remain convinced that the makers have gone down this technology road to take the cars out of the home mechanics and small garage domain, and to make sure they have a fair to middling chance of being scrap at 7 years old anyway.
The limp mode is just one of many devices to squeeze the motorist into convincing themselves they need to renew and upgrade and to get a vehicle thats just that little bit more clever than before.
Remember though, there are some incredibly thick drivers out there, topping up the oil when the oil light comes on being one example, the makers are doing the usual and catering for the lowest common denominator.
Regards all.
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I reckon cars are better in pretty much every respect than what they were 20 years ago. And that includes reliability. I've had a string of Japanese cars and never had a problem, even though they've had complex things like climate control, EBA, ABS and multiple airbags.
I also think that 'limp home' mode is there to get me home when something goes wrong with the car, and with minimal chance of damage to engine or emission control system. Maybe I'm 'incredibly thick', but to me it seems the guys who engineer these things know what they are doing and have done a pretty good job so far. I also think (maybe naively) that 'the state' has nothing to do with limp home mode and its just some useful lines of software put in there by the programmers. Mind you, I've not been wearing the metal foil hat these past few days, so maybe 'they' have finally got to me......
Of course there are complexities I wouldn't buy into (like CR diesel).
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I was thinking more along the lines of emission control regulations and the consequences of allowing cars to have more power in limp mode, even if briefly, to get out of dangerous situations.
So i`m postulating that sometimes, power in limp mode is being determined more by state control - emission regs - rather than in totality, safety concerns for the engine.
After all, what is there to stop an engine with a faulty MAF flagging a warning, but continuing to run relatively normally - defaulting to the same parameters as before the fault- other than falling foul of emission regs.
It seems on some cars you can just unplug the MAF - at least for a while- to restore normal power, however the ECU is coded to default straight into limp mode instantly, regardless of driver safety.
Sure, some faults would warrant an engine shut down or default to limp mode. But there seems to be a whole raft of more minor issues which cause an instant - no concern for driver safety- drop into limp.
Surely a much more flexible program could be run regarding limp, even if the consequences were a breach of state determined emissions for a brief period.
But to do that, regulations would have to change.
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have a fair to middling chance of being scrap at 7 years old anyway.
Can't quite see that myself - since electronics started to take over in a big way in the 90s it seems cars last longer and are more reliable... when I started driving in the mid 70s a 7 year old car in decent nick was unusual to say the least, nowadays there are lots of cars 10/12 years old in excellent condition, including their electrics! Computers in cars used to be a bit hit and miss, I'd suggest that today they are very reliable... there may be the odd duffer but most are good.
Edited by b308 on 16/09/2008 at 10:53
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I'd really want some chapter and verse before accepting that state control was in play here.
Limp mode is invoked when the ECU detects a fault code. As Screwloose and others will tell us the code is not a diagnosis, just an indication. The same code may point to more than one possible fault with differing consequences. Given the risk to expensive bits, cats being the most obvious, it's not surprising that designers err on the side of caution.
I've had the Xantia (110HDi) go into limp and the effect seems to be to limit the engine to 3000rpm. Reaching limit rpm in acceleration is like hitting a steep hill, but using the gears carefully it's still possible to maintain a motorway cruise of 65/70. If limp cuts in over 3k rpm the loss of speed is relatively slow and undramatic in an M/way lane 3 scenario, though I guess it could cause some sphincter clenching in a marginal A road overtake.
Edited by Bromptonaut on 16/09/2008 at 21:51
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