Hi all. When I start my Bongo and am idling in Park, waiting for kids to sort belts out or whatever, the revs creep up from just under 1000rpm to 2500rpm I'm not sure exactly how high they'd go if I let it continue. If I change gear they drop back down, but if I go back into park without moving off they pop straight back up again.
Having had limited driving experience I'm sure this isn't normal but if it is sorry to waste your time! If it's not normal any ideas what's happening? Foot is off pedal when this happens and I've even checked the pedal wasn't stuck by gently pulling it upwards. No movement felt.
Thanks for any help, and hopefully it's not a stupid question lol.
Revs increasing when idling - might be normal??
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Northern Bongolow
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Re: Revs increasing when idling - might be normal??
petrol or diesel
Re: Revs increasing when idling - might be normal??
Diesel sorry should have added that
Re: Revs increasing when idling - might be normal??
its normal though dont recall mine going quite that high,it should go back to normal once warm or you touch the throttle
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Northern Bongolow
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Re: Revs increasing when idling - might be normal??
what age of diesel is it as there are 2 basic differences.
if you think of a diesel as a basic engine that when started will just run at a set speed when warmed up, then add in the controlling sensors you can then think of how this is achieved.
when cold the bongo will start and run slower than the ecu has determined it should, the rough aim is about 900 revs, to acheive this is has 2 solenoids that pick up the revs to this point and no more, when a certain temp is obtained these turn off and the engine runs happily at tick over usually just about 900.
there are other sensors that tell the ecu what is actually happening. the crankshaft speed sensor and cam shaft sensors relay speeds back to the ecu to confirm all is in limits.
i would check the cold start solenoids are not stuck on, this would have the effect similar to the old days of leaving the choke out making the engine race, it could be that the vac pipes are melted to the solenoids and or are sucking flat holding up the vac, check the wires to the sensors for the crank etc, even test the sensors, the diesel crank sensor is known to get oil pooling behind it and random events can happen, simply remove one 10 mm bolt that holds in in place, let the oil drop out or wipe out the socket, then wipe the face of the sensor then refit.
when the engine is warm check that the sensor on the end of the throttle cable is being pushed in, or is still wired up or is operating, this is a simple plunger switch that is pushed by the throttle cable end when the cold start solenoids come off at about 50 degc.
does the bongo start at normal revs then gradually rise to the stated 2500 revs and stay there indefinitely. at 2500 revs the turbo is about to kick in
if you think of a diesel as a basic engine that when started will just run at a set speed when warmed up, then add in the controlling sensors you can then think of how this is achieved.
when cold the bongo will start and run slower than the ecu has determined it should, the rough aim is about 900 revs, to acheive this is has 2 solenoids that pick up the revs to this point and no more, when a certain temp is obtained these turn off and the engine runs happily at tick over usually just about 900.
there are other sensors that tell the ecu what is actually happening. the crankshaft speed sensor and cam shaft sensors relay speeds back to the ecu to confirm all is in limits.
i would check the cold start solenoids are not stuck on, this would have the effect similar to the old days of leaving the choke out making the engine race, it could be that the vac pipes are melted to the solenoids and or are sucking flat holding up the vac, check the wires to the sensors for the crank etc, even test the sensors, the diesel crank sensor is known to get oil pooling behind it and random events can happen, simply remove one 10 mm bolt that holds in in place, let the oil drop out or wipe out the socket, then wipe the face of the sensor then refit.
when the engine is warm check that the sensor on the end of the throttle cable is being pushed in, or is still wired up or is operating, this is a simple plunger switch that is pushed by the throttle cable end when the cold start solenoids come off at about 50 degc.
does the bongo start at normal revs then gradually rise to the stated 2500 revs and stay there indefinitely. at 2500 revs the turbo is about to kick in
Re: Revs increasing when idling - might be normal??
Thanks for those replies. It's a 95 diesel.
The bongo starts running at 900 revs, then immediately starts to creep up. If I just leave it to carry on it will eventually go back down to 900-1000 revs, just before it hits 2300 usually.
I shall check the solenoids as suggested, thanks so much for the extensive information!
The bongo starts running at 900 revs, then immediately starts to creep up. If I just leave it to carry on it will eventually go back down to 900-1000 revs, just before it hits 2300 usually.
I shall check the solenoids as suggested, thanks so much for the extensive information!
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Northern Bongolow
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Re: Revs increasing when idling - might be normal??
lift the drivers seat and flap up and then start it up and watch what happens to the fuel pump arm/cable. on the driver side top of rocker cover are 2 solenoid switches that have thin black vac pipes coming from and to them, follow these pipes down the back of the fuel pump to the silver diaphragm on the side of the fuel pump, see if you can spot a melted or trapped pipe.
its only a 10 min job to check the crank sensor as said above, both these things can affect the revs.
its only a 10 min job to check the crank sensor as said above, both these things can affect the revs.