Technical ENGINE WONT REV ABOVE 2750rpm

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Technical ENGINE WONT REV ABOVE 2750rpm

treetop

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Hi everyone I am new to the forum. I hope someone may be able to help. I have a 2011 Motor home on a Ducato X250 2.3Lt 130 bhp. When I start the engine , whether the engine be hot or cold, it wont run above 2750 rpm unless I depress the clutch after start up, then everything seems OK. It does this whether I start the engine with the clutch pedal depressed or not. The engine is not making excess smoke of any kind and I can hear the throttle valve closing a few seconds after engine stops, the vehicle is regularly serviced and it is not showing any fault codes. Every 6 months I put forte diesel system cleaner in. Can anyone offer any advice and suggestions as to the problem and a possible cure. Thanks for reading this post, I hope someone can help.
 
This is the behaviour of the 2.3Lt engine with a partially opened throttle valve.
The valve is closed by a solenoid when the engine is stopped, after a few seconds the power is cut and a coil spring opens the valve. The spring is in a narrow chamber between the valve body and the (rotational) solenoid under it. The presence of rust can prevent the valve to open fully.

I don't think the clutch pedal is part of the equation: waiting a few minutes probably has the same effect. To confirm this, remove the 2-pole plug from the solenoid, start the engine, depress the clutch pedal and once the engine runs normally, switch it off. The engine now takes more time to stop. Then start again: if my diag is correct, the engine will rev all the way without delay.
 
Thank you CDK for your reply. I will try as you suggest ,the selenoid valve you talk about would that be the one that controls the vacuum to the egr valve situated just below the windscreen scuttle? Thank's again.
 
Hello again CDK or would the selenoid you mention be the one on the throttle valve which is difficult to get to between the rad and valve body? Thank's again.
 
Nope, the solenoid is situated directly under the throttle valve. It looks like a black electric motor.
 
Thanks CDK I'l take a look.this morning I started the vehicle without depressing the clutch and allowed it to run for twenty minutes until the temperature gauge was at normal running temp unfortunately the engine would still only run at 2750rpm. I depressed the clutch and bingo all is fine, I will try you suggestion but I think that I may disconnect the negative lead on the battery and clean the various connectors including the ones below the left hand headlight which I'm told can cause problems.(That is unless anyone think's that this could cause more problems).Any thought's would be welcome,Thanks again.
 
The clutch issue is peculiar....is there an electrical switch on the pedal arm for the cruise control or something? If so you could try disconnecting the leads to it or connecting them together (depending whether it's NC or NO)
 
Yes Crossingkeeper the vehicle has cruise control pressing the clutch or brake de-activates it,after start up and the first depress of the clutch (cruise control off although I haven't tried with it on) the vehicle will run and rev as normal. I think it must be a communication problem hence the thought about cleaning the connectors. Just at the minute it's tipping it down here and the vehicle is outside when it stop's I'l go out and remove the clutch pedal switch I can then put my multi-meter on to see if it's N O or N C . I'm just a little worried about the ECU I don't want to damage anything. By disconnecting the battery earth will this be sufficient to prevent any damage? Thank's for your input.
 
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