my Punto Sporting MK1 1998 is having a strange problem. When i drive in my
town, were we have a speedlimit of 30 km/h, i drive at 2000 refs/m
in second gear and than its if the engine has a problem with the fuel cut
off system. I don't do anything with the throttle, but the car starts
bucking like it is short of fuel. When you make more revs, say 2500 the
problem is over.This problem has shown in all the gears round 2000 refs/m.
I know that the fuel cutoffsystem comes in when you take your foot of the
throttle and gives fuel at 2000 refs/m.
I think the problem is due to that fuelcutoffsystem. Although someone told
me it could be, that the throttlevelvehousing is dirty.
Has anybody an answer for this problem?
Totally remove the throttle cable so the throttle can be freely rotated by
Gently move end stop to end stop (especially at the nearly closed end)
feeling for any drag, snatching etc.
The other possible cause is that the ECU which is self adaptive has got
itself all confused and needs retraining.
The sequence (from memory) is as follows:
1) Disconnect battery for 30 minutes
2) Reconnect bat.
3) Start car and allow to idle till fan cuts in 3 times
4) Rev car at a steady 3000 rpm for five minutes
5) Release throttle and allow engine to idle for 1 or 2 minutes
6) Switch off
Please report back how you get on.
Initially for your case you can skip the throttle cable removal and manual
operation of the throttle plate. Go straight in at step 1. Only 30 minutes
Reading the info again I should add that step 3) starts with a cold engine
so steps 1 & 2 can be done overnight. Steps 3 to 6 could take up to 30
i have followed your instructions, and it looks very prommissing, because i
have driven for a few miles now at 2000 refs. and the engine
responded normaly on the throttle and the engine didn't buck at all.
The only thing i want to try now is drive a few miles, when the engine is
cold again.(because with a cold engine, it was the worst)
I'll report back again then.
For now: thank you, o great Fiat wizzard.
i have driven with the car this afternoon (starting off with a cold engine).
I must say the car is much better now, although he bucks a little (when
the engine is cold), but not as much as before, because before i had to
push down the clutch to stop the car from bucking.
That is completely over now. I hope it stays this way.
Well when you get time you can unhitch the throttle cable and check for the
smooth operation of the throttle plate. Also a gentle air clean of the idle
solenoid actuator followed by a quick squirt of WD40/other light oil won't
go amis. Also a little WD40 around the throttle plate spindle can only help
Reasoning: With active mechanical idle control onto the throttle plate
linkages (as opposed to air bypass methods) then any snatching will result
in the actuator pushing harder to overcome excessive stiction and then when
overcome will go into overdrive resulting in rapid backoff and so the cyle
I need not add that clean air filters and spark plugs in good condition help
to reduce other air/fuel combustion problems that could otherwise add to the
problems of other systems.
I will check the smooth operation of the throttle plate, in the near future.
My car gets a check up every year at my local Fiat dealer, and than the
sparkplugs are replaced and the airfilter also if necessary.
Thank you for the information and explanation.
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