Engine Overrun

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Rob 90

Active Member
Posts
93
Location
Suffolk
My 2.5 NA when warm does not instantly reduce revs when letting go of the accelerator.
It revs high for about 5 - 10 seconds which does not seem allot but sounds worrying and it effects engine braking when slowing down. I have checked the cable etc and this is not sticking. Also just changed engine oil / filter / removed and cleaned out sump, dipstick showing correct level.
I have read that over run can be caused by the engine running on by burning the engine oil as fuel, but this always seems to end in the engine not able to be turned off and seizing? Does anyone have any suggestions?
 
Couple dumb questions:
1. how much oil is it using?
2. How bad is it breathing out the valve cover?
3. Does it do this if the breather from the valve cover is disconnected from the air intake?

Were it me I'd get it hot, then get under the hood and rev it and see what it does while examining it. If it does stay over-revved, Rev it then disconnect the fuel solenoid on the injection pump - pull the wire. if it still stays revved then dies it is running on its own lube or something else I'd suspect - if it dies right off then it's an oddity in the injection i'd think.

just blue-skying here - not certin but this seems a good test.
 
Check that it's idling on the governor and not the 'throttle' arm. On mine, some ham-fisted individual had adjusted the idle speed by winding up the lower stop on the throttle arm, rather than the actual idle governor, and the idle governor was itself set too low to compensate. As a result, the fuel never really shut off when you lifted off the pedal and gave similar symptoms. Set everything up properly and the response immediately improved.
 
Thanks
  1. It uses hardly any oil probably top up a little at about 3000 miles.
  2. Get a bit of mist out of the rocker cover breather
  3. Breather from rocker cover is just a pipe that goes down side of engine, not connected to air intake?
Will try revving and removing fuel cut off test and try setting up checking throttle idle settings and let you know if this gets any results.
 
Checked through all above and it turned out it also was idling on the throttle arm, it was not even reaching the lower stop. Adjusted the cable which dropped it slightly and also lowered the tickover on the idle governor. This has done the trick, easier to change gear now as it reduces revs quicker.
Also sounds better on a slower tickover apart from the window rattle (MOD sliding windows) which is probably why the tickover had been set high ?
Cheers.
 
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