2.5L diesel engine stalls at idle or low RPM

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DesertRanger

New Member
Posts
10
Location
Lapid, Israel
A new problem developed soon after fixing few shorting leads of the transmission loom and after changing the diesel filter base and hose connecting the filter to the fuel injection pump (FIP) input. It is possible that the timing of the problem occurrence and the fixing and replacement of parts is purely coincidental.
What happens is that after 10 or 15 minutes of driving from cold start, while stopping at a traffic light or parking, the engine stalls completely without warning. No faults are reported. I took a look at the filter and things looked fine , however the fuel hose connecting to the FIP, near the securing nut, was covered with a thin black layer of what seemed like burned oil.
I opened the connection, checked the swage gasket and nut, retightened the unit and drove it until same thing happened again.
Occasionally there are sudden losses of power at highway speeds but the engine recovers quickly. It does seem that I have a air/fuel mixing problem or some sort of sensor problem that happens at low RPM but it is difficult to find the cause without an error message.
Searching the past threads on this issue I could see that I am not the only one who has had this problem but it seems rather limited in terms of frequency of appearance. Any help is really appreciated as always.
 
I'm not sure if this helps but what you deiscribed in your post was very very similar to the syptoms I had just before my injector number 4 packed up. My p38 is an auto so very very hard to stall. But would stall at traffic lights and jolt when doing motor way speeds.. Have a look at your 4th injector and the wiring coming from it. I hear some people bodge them together when they replace the injector because you need a fairly expensive special socket to allow for the wire.

Hope this helps you :)
 
Littelwill said:
I'm not sure if this helps but what you deiscribed in your post was very very similar to the syptoms I had just before my injector number 4 packed up. My p38 is an auto so very very hard to stall. But would stall at traffic lights and jolt when doing motor way speeds.. Have a look at your 4th injector and the wiring coming from it. I hear some people bodge them together when they replace the injector because you need a fairly expensive special socket to allow for the wire.

Hope this helps you :)
Click to expand...

Injector number four fault will cause limp mode if it fails and power loss at higher RPM if intermittent. But will not cause a stall unless the static timing is totally off the scale.
 
I'm sure your right Wammers. But still worth checking. I tryed all sorts before I figured that it was the injector giving me the trouble.
 
I don't want to give you false hope but when I had a very similar issue just over a year ago and was fearing FIP and fuel quantity servos etc (I too had no faults) all it turned out to be was that I hadn't screwed the fuel filter on tightly enough post service so air was getting into the system. I screwed it on tighter and afterwards it was fine.
 
Littelwill said:
I'm sure your right Wammers. But still worth checking. I tryed all sorts before I figured that it was the injector giving me the trouble.
Click to expand...

Number four injector measures the point of injection. The point of injection is compared by the ECU to the CPS readings. The timing solenoid then adjusts the point of injection to coincide with the desired injection point subject to engine speed and load. 45 to 55% modulation of the timing solenoid at idle, ideally 50%. Unless that is way out of range, meaning the static timing is a long way out, i cannot see how a number four injector fail can result in a stall.
 
Wammers, there's a little track in the electronics bit in the top of the fuel pump. What would happen if dirt got on that track? Would it put too much fuel in or too little? Or is that barking up the wrong tree?
 
Grrrrrr said:
Wammers, there's a little track in the electronics bit in the top of the fuel pump. What would happen if dirt got on that track? Would it put too much fuel in or too little? Or is that barking up the wrong tree?
Click to expand...

The track is the feedback potentiometer for the fuel quantity servo. ECU decides where servo should be as needed for engine speed/load request either from CPS with idle switch active or from throttle pot request/load being applied. If the track is corrupt stall at idle is possible. But that would show on diag as a quantity servo error. Basically at idle, engine speed is maintained at 750 RPM +- 50. If the RPM as detected by CPS falls below that through say load applied (Aircon coming on or Alternator being loaded) fuel is increased to compensate for load applied to maintain RPM. Then reduced as load is removed. Maintaining a steady tick over. If the feedback pot is faulty the ECU doesn't know where the fuel servo is so will shut down the engine. But as i said earlier if that is the case it should show on diag. The servo works against spring pressure, so if contact is lost with the pot and the ECU stops applying voltage because of this the spring pulls the servo to zero fuel position and the engine stops.
 
Thanks a lot for all your replies and guidance. I've replaced injector number 4 about 3 months ago using the special long socket with a cut out which protected the electrical feed from getting damaged. Things worked well after that and the warning instrument panel light went off. I checked the cables and they seem fine in that area.
Wammers, thanks for the hint on the fuel quantity servo. I haven't had the car inspected by a service shop. The thing is that the mechanics in Israel except for just very few aren't able to diagnose properly failures of this sort. One cannot rely on their expertise and therefore most Range Rover owners are either mechanics or enthusiasts (like me) and do the work on their own. I never had to trouble shoot this servo so I would appreciate a little guidance on where to start. The CPS seems like the original one so it might be the culprit as well. Is it a Hall sensor? I could check it by using an external piece of magnetic steel or small magnet if it is...
 
DesertRanger said:
Thanks a lot for all your replies and guidance. I've replaced injector number 4 about 3 months ago using the special long socket with a cut out which protected the electrical feed from getting damaged. Things worked well after that and the warning instrument panel light went off. I checked the cables and they seem fine in that area.
Wammers, thanks for the hint on the fuel quantity servo. I haven't had the car inspected by a service shop. The thing is that the mechanics in Israel except for just very few aren't able to diagnose properly failures of this sort. One cannot rely on their expertise and therefore most Range Rover owners are either mechanics or enthusiasts (like me) and do the work on their own. I never had to trouble shoot this servo so I would appreciate a little guidance on where to start. The CPS seems like the original one so it might be the culprit as well. Is it a Hall sensor? I could check it by using an external piece of magnetic steel or small magnet if it is...
Click to expand...

You need diagnostics to read any fault codes, without that there is not a lot you can do. If you play with the CPS, DO NOT remove the bracket it is bolted to. Take the CPS off the bracket, but DO NOT loosen the bracket. Special tool needed to set position of CPS if bracket is moved. I doubt it will be the CPS more likely quantity servo.
 
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