Hello, Please excuse the wording of the title, it is the only way I can describe my issue. I have a 95 Discovery I V8, 300,600klm, which has consistently run very well. I'm a DIY and repaired/serviced the vehicle for the last 20 years, I call it occupational therapy. On this occasion I'm stumped and cordially ask for your help. The condition arises when highway travelling at ~2000rpm (80-100k), temperature normal, the engine begins to cut in/out (If you get my drift - fibrillate). Two actions remedy the problem (i) put the throttle flat to the floor and (ii) reduce speed and the motor will re-engage to normal running. Initially, I went to the ignition system and replaced the coil, amplifier, HT leads and plugs. I cleaned the distributor cap. I also wired in a LED to the coil, which indicates there is no power loss to the coil when the problem occurs. Which led me to the fuel system. I replaced the fuel pump, there is good pressure in the fuel line. I have also cleaned and resealed fittings after replacing a valley gasket two years back. I'm assuming that as the problem is intermittent, there is integrity with the sealing, as the engine purrs in the greater run ( for instant, last month I did a 10 hour drive with no issue. Today on a 2 hour trip the fault would have incurred ~ 5- 6 times). I visualize it like a flutter value, flicking in and out of the airflow, which settles down when there is a change in the driving pattern. In appreciation, many thanks. Regards, Tony G. NZ

 

Flicking in and out of the "airflow"...... Mass Airflow Sensor, give it a cleaning and if that doesn't do it see if you can borrow one to try out. The MAF is telling the ECM how much fuel to add and timing the injector pulses, if it's on the fritz it'll stop a bank of injectors from firing. That's my guess.

 

I'd guess the VSS is on its way out. When mine wore out it would send wacky readings to the ECU which the ECU interpreted as the truck travelling well in excess of safe limits. To counter this the ECU retards ignition until the speed is back in the safe range.

 

Hello again. I first approached the forum in July 2018 with the fault my 97 Discovery 1 had with an intermittent engine cut-out when the vehicle is running in normal conditions . Frustratingly, the fault is reoccurring. There is no problem with starting, the engine purrs, idles well at 750rpm. Gear changing is in line with specification. The odometer reads 310K. Taking your advise I have replaced the coil, the amplifier (the initial though of fault), the HT wires, plugs etc. A reconditioned alternator, a secondary HT earth from the battery to the engine block. Spotlessly cleaned the MAF. Checked all fuses and continuity checked (with wiggling) all wires in the ignition wiring to distributor. I have a LED wired to the coil that confirms there is no fault with the coil. What does happen is the Rev counter responds (fuctuates) to the pattern of the fault, which indicates to me could be an earth fault? Or, maybe the ECU is reacting to a sensor which affects the fuel injection? The problem can occur on acceleration or with normal city and highway driving.
The local LR garage (good expert people) is also at a loss. It appears to be one of those problems that appear to challenge logic. Without intending to be parasitic, I would really appreciate your advise and assistance. Many thanks, Tony , Christchurch, NZ.

 

Check the wiring on the crank position sensor. It is located close to the exhaust/cat and often is fried.

 

Thank WaltNYC, I recall you mentioned this. I apologise as I should have stated my 95 Discovery 1 doesn't have a crank position sensor. Vehicle number is SALLJRM3MA128351.The Haynes manual identifies these sensors affect the ECU; Tune select resistor, coolant temperature thermistor (newly replaced), fuel temperature thermistor, by-pass air valve, Lambda sensor, fuel pressure regulator, MAF, throttle potentiometer, vehicle speed sensor (na) inertia switch (newly replaced) fuel relays ( newly replaced). Could any of these contribute to the characteristics of the problem?
A member had an issue recorded below, whereby a faulty fuel cap was restricting pressures in the tank. Is it possible that a similar low pressure event is occurring, pulling back on fuel delivery to the fuel rails? I renewed the fuel pump around 4 years ago. I appreciate your assistance. Regards Tony G.

 

Right. I overlooked (didn't read well enough) it was a '95 (dizzy). I'll go back to my initial thought. VSS

I'm curious as to why you wrote "(na)" next to that sensor.

 

Thanks, WaltNYC. My error, I thought the VSS and the Crank Position Sensor were one n the same. na meaning 'not applicable'. Again, many thanks. I'll look at it and report back. Regards Tony G.

 

Your problem sounds a whole lot like what I ran into a few years ago.

https://landroverforums.com/forum/di...eed-ecu-79498/

A '95 won't have the OBD capability so it is more difficult to diagnose precisely.

 

Hello WaltNYC. I've taken the VSS out and the housing opened in my hand. The main shaft is wobbly with a lateral movement. The wire connector is clean and firm. I clean the unit, greased the shaft, resealed the housing with silicon RTV and reassembled back into the truck. The unit still with the wobbly shaft, as I thought that it may have required to find its own centre. On the test run, where there was a speedo reading before the operation, now it's dead, although it flicked on two occasions. So the unit is able to function.


Before starting the job I consulted the local LR garage/parts, they quoted NZD500 ( ~USD320) for a new replacement. In the interim, from your link I found the article on refurbishing the VSS. I'll work on this to reduce the wobble and apply the proper lubricant.


Regards, Tony G.