V8S - Intermittent Engine Cutting Out
Discussion
Hi All
Yesterday out of the blue the engine cut out during a steady drive. It restarted but then cut again and this continued as I nursed it home for a few miles. Sometimes it would just cut and other times it would drop revs then climb again maybe 4 or 5 times and then cut out. I've had the car 8 years and there's never been any issues like this before or other strange symptoms recently.
Before I start investigating or throwing parts at it, can anyone recommend a sensible order of checking? I have the roverguage so can always use that in conjunction with any checking/testing too.
Thanks a lot
Rob
Yesterday out of the blue the engine cut out during a steady drive. It restarted but then cut again and this continued as I nursed it home for a few miles. Sometimes it would just cut and other times it would drop revs then climb again maybe 4 or 5 times and then cut out. I've had the car 8 years and there's never been any issues like this before or other strange symptoms recently.
Before I start investigating or throwing parts at it, can anyone recommend a sensible order of checking? I have the roverguage so can always use that in conjunction with any checking/testing too.
Thanks a lot
Rob
A test lamp connected to the coil positive and another to fuel pump positive would tell you whether either of these are losing power.
If it's affecting both, the dreaded yellow connected would be the first suspect. It's worth inspecting that anyway.
If it's affecting the fuel pump only, I'd suspect a fuel pump relay on the way out. Failing after it has been on for a while and then recovering after a few minutes is a classic symptom of a failing relay.
If it's affecting both, the dreaded yellow connected would be the first suspect. It's worth inspecting that anyway.
If it's affecting the fuel pump only, I'd suspect a fuel pump relay on the way out. Failing after it has been on for a while and then recovering after a few minutes is a classic symptom of a failing relay.
Hi
Thanks for the suggestions. I'll check these out later. I tried Rover Gauge yesterday and no fault codes showing and using it to open stepper and view MAF rate and throttle position all seemed OK. But the the engine ran fine for about 15 mins which I suppose is what makes intermittent faults so tricky to track down.
Thanks for the suggestions. I'll check these out later. I tried Rover Gauge yesterday and no fault codes showing and using it to open stepper and view MAF rate and throttle position all seemed OK. But the the engine ran fine for about 15 mins which I suppose is what makes intermittent faults so tricky to track down.
Check the yellow connector first. Take it apart and check it thoroughly. Better still, cut it out and solder the connections.
Then it is systematic checks. Do things one item at a time.
The TVR wiring looms were pretty ropey so it could be one or twenty faults.
Wendy (350i) was running roughly intermittently when I first got her. Started going through things and just kept finding poor factory componentry, poor quality construction, poor 'temporary repairs' and failled consumables. In the end it was the flapper AFM that was the final fault but that was fault number 39!
My view now is just to renew the wiring looms in sections when I get faults.
Then it is systematic checks. Do things one item at a time.
The TVR wiring looms were pretty ropey so it could be one or twenty faults.
Wendy (350i) was running roughly intermittently when I first got her. Started going through things and just kept finding poor factory componentry, poor quality construction, poor 'temporary repairs' and failled consumables. In the end it was the flapper AFM that was the final fault but that was fault number 39!
My view now is just to renew the wiring looms in sections when I get faults.
GreenV8S said:
A stepper motor fault would give problems at idle but would not cause the engine to cut out while driving.
Yes, normally. When I had a Chinese one fitted to my last Chimaera however, the idle speed was all over the place, being hard to start when cold and going up to nearly 3k rpm at junctions and when dipping the throttle. Could it not cause issues regarding an idle speed too low as well, such that the engine may stall?
ianwayne said:
Yes, normally.
When I had a Chinese one fitted to my last Chimaera however, the idle speed was all over the place, being hard to start when cold and going up to nearly 3k rpm at junctions and when dipping the throttle. Could it not cause issues regarding an idle speed too low as well, such that the engine may stall?
Definitely could cause stalling problems at idle, but would not cause the engine to cut out in normal driving.When I had a Chinese one fitted to my last Chimaera however, the idle speed was all over the place, being hard to start when cold and going up to nearly 3k rpm at junctions and when dipping the throttle. Could it not cause issues regarding an idle speed too low as well, such that the engine may stall?
Hi
I have now checked the yellow connector on steering column and it seemed intact. I disconnected the plug and investigated it and no sign of burning or melting. I have also checked throttle position sensor and it all seems fine in it's readout by both multimeter and the rover gauge ECU signal. I also checked the MAF readings at various RPM and it seemed to all be in line with accepted values.
I've now trawled through other forum postings on similar issues and have a list (in no particular order) of possible offending items below:
Fuel Pump
Fuel Pump relay
Throttle Pot Sensor
Ignition Coil
Ignition Amp / Module
Air Flow Meter
Stepper Motor
HT Leads
Distributor cap
Rotor Arm
Wiring Loom (Ignition) Generally
ECU
Ignition Relay
Speed sensor to ECU Box and Wiring
Ignition fuses
Fuel Pressure
Vac Advance Failure
Air intake duct collapse
Spark plugs
Fuses
Petrol tank and vent
I'll start checking methodically best I can as has been suggested above also and only move onto part replacement once I'm happy with the checks. I'll keep this thread updated and if I ever fix it, what I found.
I have now checked the yellow connector on steering column and it seemed intact. I disconnected the plug and investigated it and no sign of burning or melting. I have also checked throttle position sensor and it all seems fine in it's readout by both multimeter and the rover gauge ECU signal. I also checked the MAF readings at various RPM and it seemed to all be in line with accepted values.
I've now trawled through other forum postings on similar issues and have a list (in no particular order) of possible offending items below:
Fuel Pump
Fuel Pump relay
Throttle Pot Sensor
Ignition Coil
Ignition Amp / Module
Air Flow Meter
Stepper Motor
HT Leads
Distributor cap
Rotor Arm
Wiring Loom (Ignition) Generally
ECU
Ignition Relay
Speed sensor to ECU Box and Wiring
Ignition fuses
Fuel Pressure
Vac Advance Failure
Air intake duct collapse
Spark plugs
Fuses
Petrol tank and vent
I'll start checking methodically best I can as has been suggested above also and only move onto part replacement once I'm happy with the checks. I'll keep this thread updated and if I ever fix it, what I found.
I had similar symptoms on my Griffith 4.0 It would start, engine would run, and idle perfectly, but after a short drive it would stutter and cut out. Long story short it turned out to be the ECU. I bought a suitable year Range Rover ECU and swapped over the TVR chip and hey presto, all good. See if you can find someone with an ECU to try. Make sure its the ECU with the removable chip though.
Hi
When I find time, I'm working through this list. I'm having real trouble as the problem is so intermittent that I could go for a half hour drive without a problem but another time not so much. Anyway, I was just looking at fuel pump relays here https://tvr-parts.com/tvr-parts/part-details/tvr-m... but it says 2 required per car. I could only detect one fuel pump relay by listening and feeling for it. It's on the loom rather than plugged into the relay box. Any ideas why 2?
When I find time, I'm working through this list. I'm having real trouble as the problem is so intermittent that I could go for a half hour drive without a problem but another time not so much. Anyway, I was just looking at fuel pump relays here https://tvr-parts.com/tvr-parts/part-details/tvr-m... but it says 2 required per car. I could only detect one fuel pump relay by listening and feeling for it. It's on the loom rather than plugged into the relay box. Any ideas why 2?
One relay is the ECU main power relay, the other is for the fuel pump.
A failing relay can cause intermittent problems like this.
To check the fuel pump relay, connect a small bulb across the fuel pump terminals with a long lead so that it can be positioned in sight of the driver. If this flickers or goes out you know you have an electrical problem.
A failing relay can cause intermittent problems like this.
To check the fuel pump relay, connect a small bulb across the fuel pump terminals with a long lead so that it can be positioned in sight of the driver. If this flickers or goes out you know you have an electrical problem.
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