My little diesel fiat panda is having problems, every so often when you start it the revs wont go over 3k, you can put your foot fully down and there is only the slightest response, after a while however it starts working normally again...just wondered if anyone had a clue what it could be so I have some idea when I take it to the garage and they try and tell me something ridiculous...
Technical Revving problems
- Thread starter Gabriel2k
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Technical Revving problems
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Some cars will prevent over revving a cold engine straight from start up, but this doesn't usually apply once in gear and moving.
My Diesel Jag won't sit there cold and rev past 2000 rpm until I put in it gear and drive.
So if it's a driveability issue it maybe your problem is a sticking turbo actuator arm.
A turbo will spin faster the more exhaust gas passes the blades, so the more you rev, the faster it spins and so on.
To prevent over boost, the exhaust side has a little bypass or wastegate, this should open when the turbo starts to reach it's safe maximum boost.
(the Panda Multijet has this wastegate system, though other turbos can have variable blades instead of a wastegate, but they are operated and work in the same manner)
The wastegate is worked by a vacuum (though some manufacturers now use electronic motors) that operates an arm in the turbo, this arm (actuator) can stick with soot and jam the wastegate in a closed position.
Some reckon it's because you need to boot it more often!
If this happens (it's fairly common) the ECU will detect too much boost in the intake side of the turbo when accelerating (that's why it often happens when you floor the pedal) and will trip the engine into limp mode (restricted performace) to safeguard the engine.
This will usually be accompanied by an engine management light on the dash and will all usually reset when the igntion is switch off and back on again, as it then doesn't detect the fault until next time it's accelerated and you start all over again!
Often the fix from a dealer is to replace the turbo, but the actuator can be worked manually or even cleaned out to free it off.
My Diesel Jag won't sit there cold and rev past 2000 rpm until I put in it gear and drive.
So if it's a driveability issue it maybe your problem is a sticking turbo actuator arm.
A turbo will spin faster the more exhaust gas passes the blades, so the more you rev, the faster it spins and so on.
To prevent over boost, the exhaust side has a little bypass or wastegate, this should open when the turbo starts to reach it's safe maximum boost.
(the Panda Multijet has this wastegate system, though other turbos can have variable blades instead of a wastegate, but they are operated and work in the same manner)
The wastegate is worked by a vacuum (though some manufacturers now use electronic motors) that operates an arm in the turbo, this arm (actuator) can stick with soot and jam the wastegate in a closed position.
Some reckon it's because you need to boot it more often!
If this happens (it's fairly common) the ECU will detect too much boost in the intake side of the turbo when accelerating (that's why it often happens when you floor the pedal) and will trip the engine into limp mode (restricted performace) to safeguard the engine.
This will usually be accompanied by an engine management light on the dash and will all usually reset when the igntion is switch off and back on again, as it then doesn't detect the fault until next time it's accelerated and you start all over again!
Often the fix from a dealer is to replace the turbo, but the actuator can be worked manually or even cleaned out to free it off.
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Does this happen with rain? I had similar symptoms till I duck-taped up a screw-hole under the windscreen wipers just above the engine. Water had been getting in there and the engine took a bit of a lull before eliminating it, and taking off... I believe a few others have used some pond liner or sealant for this purpose.
Try that before going through new turbo, etc. Bit cheaper!
And a regular good boot when the engine is warm to clear its throat is recommended too.
Try that before going through new turbo, etc. Bit cheaper!
And a regular good boot when the engine is warm to clear its throat is recommended too.
