Rover 25 (1999 - 2005) - 02 1.4 16v engine misfire

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Tue 15 Apr 2008 23:04
02 1.4 16v engine misfire - giamburrasca
My partner drives a W-registered Rover 25 1.4 iS 16v with around 70k
on the clock.

It starts normally each morning, but within 300 yards to three miles,
the engine loses power drastically, misfires and will not respond to
the throttle. Occasionally, she can coax the car through this in 10
seconds or so, but usually it involves pulling over and listening to a
very noisy shuddery engine note that rights itself after a minute or
two.

This problem has defeated the motor trade up to now, including a Rover
Main dealer (as was). Running diagnostics either shows nothing amiss
or refers to faults that are not pertinent to this model. Spark plugs
and fuel filter have been replaced, and the fuel lines flushed, to no
avail. The only significant work undertaken on the engine prior to
this problem occurring, was to replace a blown head gasket at 55k.

It has been suggested that the problem may be with the ECU and that a
replacement would cost about £400.

Do you agree, and if so, do you have a view on the viability of such
an investment, given that the rest of the car is sound and has just
sailed through its MoT
Or do you have another theory?
Thanks in advance.

Slightly re-formatted, the OP was directed by HJ here

Edited by Pugugly on 15/04/2008 at 23:49

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Tue 15 Apr 2008 23:57
02 1.4 16v engine misfire - Screwloose
Another theory - sticking valves.

Attach a vacuum gauge to the breather stub on the inlet manifold and watch it as it warms at idle from cold - should be steady as a rock around 20" Hg; any sudden change, worry.

Useful to have a fuel-pressure tester attached at the same time; in-tank pumps have been known to be temperamental too.

Edited by Screwloose on 15/04/2008 at 23:58

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Wed 16 Apr 2008 22:22
02 1.4 16v engine misfire - scrapmetal
Front oxygen sensor, done loads.
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Wed 16 Apr 2008 23:01
02 1.4 16v engine misfire - Screwloose

That's another distinct possibility; though, at 300yds, it would need to be combined with a faulty coolant temp sensor sending it into closed loop too early.

I'm surprised that they haven't tried a coolant sensor already.
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