I have had power loss and backfiring in my car the last month, and
having taken it to a garage they have replaced the plugs( which
obviously were not changed at the last Merc service) and it was
obvious one had been tracking for quite a while. While it has
improved the performance, it is still not quite right. Less backfiring
, but still there, especially at low revs when trying to accelerate,
and a definate loss of power when trying to accelerate from low revs.
High speed travelling seems to be fine, once on the moterway all if
Could the tracking have damaged the coil?, and if so is it easy to
I would do all the basic checkup before doing more major works... first...
how is your timing? What is the condition of the spark plug wires... you
need to use a ohmmeter to measure each wire... they should be between 1000
and 1300... and all wires should be near each other except the ignition coil
Take out your distributor cap... clean the brass contacts inside where there
is black marks... clean it until you see brass again... same for the
rotor... on the edge and the center.
Run fuel injection cleaner for one tank... and then run Marvel Mystery Oil
on the second tank (read label for amount to put in).
Never mind. Just share my experience. That kind of loss power sounds like
the air leak after the air mass sensor. Check all the duct first, if there
is a leak it causes intermittently loss of power.
The guy at the garage sprayed around the engine while it was running,
and found no air leak. The spray enters the leak and runs the engine
quicker and so can detect where the leak would be, or so he said.
I don't know how the guy could find out there was a leak on the air inlet
duct of a normal aspired (non turbo or supercharged) engine by spraying some
kind of funny powder. What you need to do is to do it yourself: check the
throttle body for any broken or deformed duct. You may also loose the duct
clamp and remove the ducting for inspection.
This kind of power loss happens on most older W202 1993-1995. BTW could you
specify what vehicle you have. 190E? or C180
Also this kind of power loss is quite common after changing spark plugs,
because in order to access the spark plug cover, the ducting on top of the
engine must be undone first. Poor workmanship contributes this kind of power
loss and gave me 3 easy jobs (piece of cake) in last year.
Keith :) E14 4NS London
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