Rover 420 running 'rough'

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Nemo2000
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Joined: Mon May 09, 2011 8:23 pm

Rover 420 running 'rough'

Post by Nemo2000 » Mon May 09, 2011 8:28 pm

I have a 2-litre petrol Rover 420, 12 years old, done 46500 miles. For last few months car only used once or twice a week for fairly short journeys.
Suddenly the engine has started running 'rough' intermittently when accelerating. Get the car out, set off thru' town, every time I accelerate it 'hiccups', shudders, jerks (sometimes with knocks/rattles) then goes OK. Out on the open road going above 30mph then usually OK - slow down/speed up no problem - but if I have to slow down for roadworks, speed-limit etc then the problem usually (but not always) returns. Only solution in town or slow-moving traffic seems to be to run at higher revs and in lower gear than normal, and accelerate very slowly. Car seems to idle OK when stationary - just the usual noises for its age. Any ideas as to possible area of problem please before I have to take it to garage for investigation???
(This may not be relevant,but.... Recently a heater hose came adrift and I lost coolant. Garage drained and refilled, but didn't get rid of all the air-locks, so I've had to top-up a couple of times since then. However coolant levels seem OK now.)

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paul williams
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Location: Telford,Shropshire
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Re: Rover 420 running 'rough'

Post by paul williams » Fri May 13, 2011 12:31 pm

Hi,

sorry about the late reply, first I should say I haven't had a 400 so the following is only a supposition. I have had the symptoms you describe on a couple of cars and each time it was due to a faulty sensor in the ECU system. Most recently it was a Rover 800 and the fault was with the EGR ( Exhaust Gas Recycler) valve which was not working and effectively shut down the engine.

The symptoms were as you describe, on the 800 it was possible to query the ECU unit and it identified the EGR fault. Replacement cured the problem with the exception of the fact that because of the wrong mixture being sent to the engine it had also destroyed the CAT. In the end the CAT was replaced with a straight through tube and all was well, it still passed the MOT on emissions.

I would suggest therefore that if possible you use the ECU fault finding system to check all is well, if thats possible on the 400, and take it from there.

The following may be of some help, its for a Rover 416 with Honda ECU:
If the ECU (found under the passenger seat footwell carpet, behind a metal sheet) finds a fault within the engine management system, it will flash a code on the LED built within the ECU but visible through the peephole in the metal sheet - Long flashes = tens, shorts flashes = units EG 1 long flash = 10, 4 short flashes = 4, 10 + 4 = 14, so you have fault code 14 - if you have the above then a pause, then, for EG 3 short flashes, you have fault codes 14 and 3. It will pause then repeat the same code again if its only the one fault code - heres the codes:

Honda ECU error codes

1 Oxygen Sensor "A" (Primary)
defective circuit or unplugged / defective sensor

2 Oxygen Sensor "B"
defective circuit or unplugged / defective sensor

3 MAP Sensor (Manifold Absolute Pressure)
defective circuit or unplugged / defective sensor

4 CKP Sensor (Crankshaft Position Sensor)
defective circuit or unplugged / defective sensor

5 MAP Sensor (Manifold Absolute Pressure)
mechanical problem / disconnected piping

6 ECT Sensor (Engine Coolant Temperature)
defective circuit or unplugged / defective sensor

7 TP Sensor (Throttle Position)
defective circuit or unplugged / defective sensor

8 TDC Sensor (Top Dead Center)
defective circuit or unplugged / defective sensor

9 CYP Sensor (Cylinder)
defective circuit or unplugged / defective sensor

10 IAT Sensor (Intake Air Temperature)
defective circuit or unplugged / defective sensor

11 CO pot or CO pot Circuit

12 EGR Lift Sensor (Exhaust Gas Recirculation)
defective circuit or unplugged / defective sensor

13 BARO Sensor (Atmospheric Pressure)
defective circuit or unplugged / defective sensor

14 IAC Valve (Idle Air Control)
defective circuit or unplugged / defective sensor

15 Ignition Output Signal
missing or defective ignition output signal

16 Fuel Injector System
defective circuit or unplugged / defective fuel injector

17 VSS (Vehicle Speed Sensor)
defective circuit or unplugged / defective sensor

18 Ignition timing

19 Automatic Transmission Lock Up Control Solenoid Valve
defective circuit or unplugged / defective solenoid valve

20 Electrical Load Detector
defective circuit or unplugged / defective sensor

21 VTEC Solenoid Valve
defective circuit or unplugged / defective solenoid valve

22 VTEC Oil Pressure Switch
defective circuit or unplugged / defective oil pressure switch

23 KS (Knock Sensor)
defective circuit or unplugged / defective sensor

30 Automatic Transmission Signal: "A" / SEAF / SEFA / TMA or TMB
defective circuit or unplugged / defective sensor

31 Automatic Transmission Signal "B"
defective circuit or unplugged / defective sensor

41 Primary Oxygen Sensor - Heater
circuit malfunction

43 Fuel Supply System
defective or malfunctioning fuel supply system

45 System Too Lean or Too Rich
malfunction in the fuel monitoring systems

48 LAF Sensor (Lean Air Fuel)
defective circuit or unplugged / defective sensor

54 CKF Sensor (Crankshaft Speed Fluctuation)
defective circuit or unplugged / defective sensor

58 TDC Sensor 2 (Top Dead Center)
defective circuit or unplugged / defective sensor

61 Oxygen Sensor, Heated - Sensor 1 (Primary)
high voltage, low voltage, or slow response

63 Oxygen Sensor, Heated - Sensor 2 (Secondary)
high voltage, low voltage, or slow response

65 Oxygen Sensor Heater (Secondary)
malfunctioning or defective oxygen sensor heater

67 Catalyst system Efficiency Below Threshold
malfunctioning or defective catalyst system

70 Automatic Transmission
malfunction with the automatic transmission controls

71 Cylinder 1 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

72 Cylinder 2 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

73 Cylinder 3 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

74 Cylinder 4 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

75 Cylinder 5 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

76 Cylinder 6 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

80 Exhaust Gas Recirculation
insufficient flow detected

86 ECT Sensor (Engine Coolant Temperature)
circuit range / performance problem

90 Evaporative Emission Control System
leak detected in the fuel tank area

91 Fuel Tank Pressure Sensor
low input

92 Evaporative Emission Control System
insufficient purge flow
Regards

Paul Williams
1929 2 litre Coachbuilt Saloon
1951 Rover Cyclops
1958 Rover P4 90 Monte-Carlo Rally Car
1998 Discovery 300Tdi 3dr
1994 Rover 620 Sli


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BruceMP
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Location: Algeria
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Rover 420 running rough

Post by BruceMP » Thu Jul 05, 2018 10:13 pm

Hello everybody,
there is a short article on the Rover 800 in the current Car Mechanics but I am not sure if it is allowed to upload it here...

Greetings,
Karsten

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47p2
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Joined: Wed Sep 24, 2008 7:51 pm
Location: Glasgow
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Re: Rover 420 running 'rough'

Post by 47p2 » Fri Jul 06, 2018 7:52 am

Welcome to the forum Karsten.

Yes please upload the article, it may help others who are having problems

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