Freelander 1 TD4 cuts out at around 3000 rpm - SOLVED !!!!!

Recent engine change all working fine, 150k miles 2002 model.

Engine history unknown but working fine - now I've done a 1000 miles been driving it a bit harder and at around 3,000 RPM under hard acceleration the engine cuts out momentarily until the revs drop a bit then picks up and drives normally. Gentle acceleration seems fine up to and (slightly over 3,000 rpm).

I'm thinking fuel feed, but any other ideas, how do you check whether it is LP pump or HP pump telling LP pump to switch off !

Any easy checks, tickover pressures seem fine on the icarsoft. Haven't tried it on a run yet, but still need to see if it is LP or HP.

There's not some kind of pressure relief valve being blown or something is there? The O rings on the HP pump pressure solenoid?

Does it smoke? Not the air induction releasing air as the turbo spools up high? Is it possible to 'blow' the EGR valve open?

Take it for a drive with the Icarsoft connected. Then display low fuel pressure, high fuel pressure and MAP pressure. Drive to the speed where the engine falters and look at the readings.

Suggest you replace the fuel filter. If it has ever been topped up with petrol the filter element binder material goes gummy, seriously impairing fuel through the filter.
My FL2 had a similar problem when I acquired it. Okay on slow acceleration; or to be more accurate, it would only accelerate slowly. RPM limited long before it should. In fact, gutless. Replaced filter and all okay.
Repeated exercise after two subsequent re-fuelling cock-ups.

Do a leak back test on the injectors.

Thanks all. I'll try a video recording of the icarsoft showing revs, map, hp and lp pressure and report back!

Ok. Results not conclusive. Cut out occurs repeatedly at 3750 rpm whether driving or in neutral. Airflow and manifold pressure steady throughout fault. Lp fuel steady at 342 to 380. Hp pressure is generally all over the place. Ranging from 38,000 to 134,000 kpa during normal driving. It did dip at point of failure but also dipped at other times. What should hp pressure be at about 4000 rpm driving? Thinking regulator or cable or hp pump???

No sure I've ever had my L Series up to 3,750 revs!

andyfreelandy said:

Ok. Results not conclusive. Cut out occurs repeatedly at 3750 rpm whether driving or in neutral. Airflow and manifold pressure steady throughout fault. Lp fuel steady at 342 to 380. Hp pressure is generally all over the place. Ranging from 38,000 to 134,000 kpa during normal driving. It did dip at point of failure but also dipped at other times. What should hp pressure be at about 4000 rpm driving? Thinking regulator or cable or hp pump???

Click to expand...

What is the MAP signal giving? I'm wondering if the boost is cutting back at the time of the fault. HP pressure looks fine, but it's worth checking the rail sensor contacts for corrosion.

Manifold pressure doesn't drop at time of fault. Reading is between 158 and 237 depending on revs. Just thrown a P0235 sensor fault so I think you may be on to it!! Can I disconnect this or substitute for another? Could this symptom fit with a vacuum leak? Replaced all hoses when engine fitted. Thanks

Is the boost pressure sensor the same as the manifold pressure sensor??? If not where be it !?

Just searched your fault code and this guy had virtually the same symptoms...

https://www.landyzone.co.uk/land-rover/fault-code.303849/

Unfortunately he didn't come back and say if the suggestions worked!

Doesn't appear to be a common fault - not many hits on the search.

andyfreelandy said:

Can I disconnect this or substitute for another?

Click to expand...

Swap the MAP sensor for the spare you had off the old engine, or replacement, depending on which one you used.

Measured resistance between pins on old sensor. Checked replacement sensor, same readings! Didn't hold out much hope but changed sensor and checked manifold sensor hole was clean. No change to fault. Checked wiring continuity from sensor plug to engine management, all good. Tried engine without sensor connected, same fault but obvs manifold pressure remained static at about 47. Drives well, pulls well. Checked all pipes by servo for turbo and all good. Just cuts at 3750 rpm. Could it be both sensors?? Unlikely I think. Resistance measurements looking into pins on sensor with mounting hole on left and numbering 1 2 3 from left...1 to 2 is 4.1K ohm. 2 to 3 is 6.1K ohm. 1 to 3 is 2.2K ohm. Polarity of multimeter doesn't change readings. Other ideas please ?!?!

Thinking about it I suppose the key question is....where does the engine management get its reference to conclude the MAP sensor is not telling the truth? If MAP is ok and getting MAP sensor fault where to look next? I may disconnect MAF and use default values to try that.

Next you could check for boost leaks. The MAP my be seeing a signal that doesn't correspond with the measured air mass from the MAF.

Carried on hunting today ! Tested for fault and restored to as before after each check. Confirmed no vacuum pipe leaks. Cleaned HP pressure valve electrical contacts. Cleaned pressure sensor connector electrical contacts. Disconnected MAF to use default values. Fitted icarsoft analyser again and noted that although it insists the fault code is P0235 - MAP sensor - the HP and LP fuel pressure dip at time of engine faltering (around 3,750rpm). So in order to find out whether it was the engine management winding down the LP pump to protect a low pressure to the HP pump I temporarily disconnected the LP Pressure sensor on the fuel filter. Result is that the fault remains after each of these tests. I am now thinking it is a genuine fuel supply pressure problem and, as I have them on the shelf, I am going to change the LP fuel pump and filter. Can't think why this would show up as a P0235 code but I think i have eliminated everything else ! Unless anyone else has better ideas!?!? Thanks........

Rethought this one. Didn't really have enough evidence to start changing anything. So - did some more tests today. Compared LP fuel pressure, HP fuel pressure and Manifold pressure at 1000, 2000, 3000 and 3500 RPM on my 2 TD4's. One has the fault and one doesn't. Guess what............ both sets of figures are very similar, no differences to worry about I don't think. Both deliver 59,000 + Kpa on HP pump at 3,500 RPM.

BUT - when the fault occurs, my fuel pump relay clicks and de-energises momentarily until revs drop then it re energises. This is why I was going for fuel pressure, but something is cutting the LP pump. The relay is fed from the engine management module which is, presumably, cutting power for safety reasons. It is not due to a low pressure to the HP pump as I have disconnected that sensor and it still does it. Anyway the HP pressure is fine.

So the new question is what would cause the engine management to cut the feed to the LP fuel pump at 3750 rpm? Where is the rev limiting done? Would the fault code indicated (MAP sensor) or boost fault shut down the LP pump?

Feel I am getting closer and haven't changed anything yet ! Won't be applying for a job at main dealers - not changed enough bits and pieces to keep them in business !

Don't think the EDC will cut fuel pressure as a rev limiter, it will just reduce the amount of fuel injected as it gets to the limit.

However, has it had a remap?

Could it be a simple case of changing the fuel filter?