How safe is "limp-home" mode?

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Beck - 14 Mar 2006 20:25 GMT

My Dads volvo (1993 240e) has had a stalling problem for ages now. One
journey it will work fine, but if he does another journey quickly after
(like popping into a shop) then the car stalls on the way home, could stall
2-3 times even only going a couple of miles.

We have replaced lots of parts and the final part to try is replacing the
air mass meter (diagnostics do indicate 1.2.1 air mass problem).

Looking on this website...
http://www.vlvworld.com/indexframe.html?VolvoRepairManual/Section_2_5.htm

It says if the car runs okay while the AMM is disconnected, then it needs
replacing. If the car runs with it disconnect it is running in "Limp Home
Mode". basically what I would like to know is how safe is it to run the car
in limp home mode? Wondering whether it would be alright to use the car for
a couple of days without the AMM attached just to see if it runs okay.
Thanks.

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M.R.S. - 15 Mar 2006 00:27 GMT

> My Dads volvo (1993 240e) has had a stalling problem for ages now. One
> journey it will work fine, but if he does another journey quickly after
[quoted text clipped - 14 lines]
> okay.
> Thanks.

Volvo 240s have a limp home mode? I highly doubt that...

It may be limping, but I don't think they intentionally did anything (unless
it's stated in the manual) for this to occur.

Modern vehicles that use bus systems are capable of doing this, under very
special circumstances.

I would not drive it around with the AMM disconnected, could affect
catalytic converter in the end... super heat it.

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Michael Cerkowski - 15 Mar 2006 06:11 GMT

> > My Dads volvo (1993 240e) has had a stalling problem for ages now. One
> > journey it will work fine, but if he does another journey quickly after
[quoted text clipped - 25 lines]
> I would not drive it around with the AMM disconnected, could affect
> catalytic converter in the end... super heat it.

They do indeed have a "limp home mode" - just do a search on "AMM"
here. It's not wise to use it for long, though, as the car tends to run
rich, and will foul the plugs and the expensive O2 sensor in pretty
short order.

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Beck - 15 Mar 2006 14:50 GMT

> They do indeed have a "limp home mode" - just do a search on "AMM"
> here. It's not wise to use it for long, though, as the car tends to
> run rich, and will foul the plugs and the expensive O2 sensor in
> pretty short order.

Thankyou both for the replies. Have ordered an AMM should be here tomorrow.
Its only second hand but it does come with 3 month warranty. Cannot afford
a new one. lol
Anyway hopefully this will fix the problem. We have replaced so many parts
trying to find out the problem, there comes to a point where the car would
have to go in and see if mechanics can sort it out.

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