G

Gothmog

New Member
Hi all,
When my 2001 dhse auto is ticking over it will sometimes just drop revs suddenly then pick up again,it never stalls but seems to be doing it more than it used too,im not sure what speed it should be ticking over at but mine sits at just over the 800 mark is that normal ?
Thanks in advance
 
750 + or - 50. Possibly the start of a fuel quantity solenoid problem. Diagnostics may pull a fault out for you.
 
Just had one doing the same, live data showed the needle lift sensor reading dropping to zero. Yet to find out if changing the sensor will cure it as the guy is going to the UK and will get it replaced there if confirmed by the indie he uses.
 
Gothmog said:
Thanks for that,no idea what parts are involved with both those replies as im no mechanic.
Click to expand...


Needle lift sensor is in number four injector, it measures start of injection point. Used by ECU to adjust injection timing for various engine speeds.
Fuel quantity solenoid is adjusted by the ECU to give the correct fuel metering at various engine speeds, manifold pressures and loads. If the crankshaft speed sensor detects a drop in RPM say at tickover, maybe due to a load being applied. The ECU will increase the fuel quantity via the quantity solenoid to return the RPM to a preset speed.
 
I had a similar problem last year and after much head scratching and discussion (and confusion) I decided, on advice from a member on here, to block the egr. Around the same time I had discussed flushing the intercooler and after some advice from wammers, I went ahead and flushed the intercooler and cleaned out the inlet manifold (which was full of sh*t) the port for the pipe to the MAP sensor was almost completely blocked. While I had a inlet manifold off I noticed the electrical connection to the needle lift sensor was not seating properly, so that may have had a bearing on what was happening. After the above work was completed.....no more problem with the revs dropping and rising.
hope this helps.
 
Well took the motor to a local landy specialist yesterday and fetched it back today he has had a peek and says its the fuel quantity solenoid at fault so he wants to send the pump off to a specialist to be recondisioned trouble is its goner cost £1200 to do,anyone know a cheaper option ?
 
Things always seem worse than what they really are, search the net for second hand parts, or try a breakers yard, £1,200.00 for a pump seems a lot, I would also search out reconditioners. Best of luck.
 
Gothmog said:
Well took the motor to a local landy specialist yesterday and fetched it back today he has had a peek and says its the fuel quantity solenoid at fault so he wants to send the pump off to a specialist to be recondisioned trouble is its goner cost £1200 to do,anyone know a cheaper option ?
Click to expand...


Just because diagnostics say fuel quantity fault, does not mean it is always fuel quantity servo at fault, it could and more than likely is, one of the sensors driving it. Did the garage check the fuel modulation? If that is out the pump timing could be retarded due to stretched chains. If the pump timing is out the engine is not recieving the correct amount of fuel at TDC static (incorrect lift on cam delivery valve shut), so at tickover the ECU has to adjust the fuel/timing servos to compensate. Any glitch in the needle sensor or crank sensor will cause the fuel/timing solenoids to lose signal and the quantity lever to be pulled back under spring pressure and reduce the fuel quantity slowing the engine. Also the pump timing will retard. In extreme cases if signal does not return quickly enough or the solenoids cannot react quickly enough and the RPM falls below 500 causing the engine to stall. It is critical to check fuel modulation and if out have pump timing set correctly to it's static setting before any further work is done. Or you maybe throwing money away.
 
Last edited:
Wammers is right, most likely a sensor. I had a similar problem I found when cleaning out the inlet manifold. The multiplug/cable to the Needle Lift Sensor on injector 4 had become loose, almost disconnected, when I pushed it back into place it seemed to solve the problem. I have attached a picture of its location (marked in red) It is under the inlet manifold. Good luck with it.
 

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Many thanks for the replies its realy appreciated,im not a mechanic and at the minute have limited use of my left hand due to a recent op on it so im having to trust in the garages that I take it to and hope they know what they are on with,might be an idea to find a specialist in this area rather than just a landy garage ?
Thanks once again
 
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