7 replies to this topic

[Robanzac]

Can anyone tell me what is experienced when you go into "limp home" mode.

I am assuming that limp home is triggered by a failure of a sensor that talks to the MEMS and that when this happens the MEMS assumes a default setting for that failed sensor to make the best of a bad job.

So, what is experience when a sensor fails?

Failures could be:
O2
Map
Throttle position
Water temp
Camshaft position.
Crank position.
and others I can't think of just right now.

Actually, thinking a bit further, output failure should also probably be included, which would be injectors and spark firing failures.

[edjohnson]

cant speak on mpi minis, never owned one.

But limp mode on my polo is as follows;

"ticks over" slightly irradically betwwen 1800rpm and 2100rpm, but drives ok.

Need to disconnect battery to reset ecu, even iif problem is solved.


ed

[The Matt]

My Pug 306 did this too.

Erratic idle, low power. Got home and did a battery reset, all was fine and has been since. Phoned up Peugeot and asked them what had caused it and they didn't know.

[Dev]

do a battery reset.

should be fine. if not let us know.

interesting this one.

[Bass Man]

Phoned up Peugeot and asked them what had caused it and they didn't know.

'course they didn't 'kin know, this is Peugeot we are talking about!!!!

[Dan]

AFAIK limp mode is the same whichever sensor has actually failed but the car will only use limp mode if it can actually detect the failure of a sensor. Some types of failures (such as the coolant temp sensor being coated in limescale or corrosion and so reading wrong) can't be detected and these will give different symptoms. Sprocket is the man to ask.

Edited by Dan, 02 February 2007 - 05:45 PM.

[The Matt]

Sprocket is the man to ask.

Yup, definitely, though there is a section in FAQ on *thinks* might be SPi systems actually

[Robanzac]

There is actually nothing wrong with my MPi, I am just curious to know what they do when a failure occurs

On other injected vehicles I have had there is usually a dash warning light or something similar that lets you know something has gone astray with the engine management.
You may not know "what" has failed (you need to read fault codes for that) but at least you know that something hanging off the ECM needs attention.

The Mini, however has no such dash warning light.
Do any of the other MEMS vehicles have a dash warning?

Maybe I should just go for a drive and disconnect a few of the sensors to see what happens.