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Occasional hiccup on my L-series.

903 Views 8 Replies 5 Participants Last post by  grahamw48
I have just joined the forum, so hello everyone ! ;)

My car is a 420SLDi Turbo, 1997 with 111,000 miles.

I bought the car in August 2003 with 62,000, and it has never let me down.

She's just passed her test again, no probs (and 30,000 since the last one)

For a while though, once or twice a day it will 'hiccup', especially at higher revs. A hesitation, nothing more, then ok.

I know nothing whatever about modern fuel management, so it's a case of keeping the bonnet shut in hopes it will go away. :indiff:

Any ideas ?

Engine-wise, all belts have been changed last year, fuel filter changed, and regular oil and filter changes. Nothing else though.
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i was going to say something to do with fuel filter till u said had been changed
Hi and welcome to the forums :) It seems to be a few more "L-series probs" of late lol!
Only just sorting mine out :lol:

You say it hesitates slightly, as if to go any faster if you push it?


Stu C
It's just like the engine is trying to cut out - kind of jerks a couple of times,
then settles down again.
Sometimes the engine light will come on.
Other than that, she starts and runs fine.
Wire chafing perhaps? A common problem by all accounts
yeh, I have this happening as well sort of.

At about 1800rpm in 3rd and 4th, if your holding the revs the car kangaroos/jerks until you either press down or let off the throttle.

Any ideas??
If it is at cruising speeds maintaining constant RPM then check the EGR (exhaust gas recirculation) valve. Try unplugging it and seeing if the problem goes away. If it does then leave it unplugged!
Just a matter of checking all the sensors on the engine really. Try the EGR sensor and the MAP (manifold absolout pressure) sensor on the bulk head. Get them from a scrappy and see what happens, if not then try other connectors and wiring and start the process of elimination. Only just cured mine, but only after the same "checking for wiring faults and sensors" process.

Hope you find the cause though!


Stu C
Thanks all.

Looks like a rooting around session. :cool:
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