V8S engine problem

[z_chromozone]

Hi all,

I am currently suffering with an annoying problem with the V8S. Every now and again the engine appears to momentarily loose power. This problem seems to be apparent when cruising, or under acceleration. I can’t say as I have noticed at tick over but it is hard to tell.

Is it likely to be fueling, ignition, or something else. As this is an intermittent problem and by it’s nature difficult to detect, I would appreciate any thoughts or experiences.

By the way, I have ordered a new dizzy cap and rotor arm. The leads are magnecore and only a year, or so old. It has always been serviced and the plugs have only done ca. 5000 miles.

It does appear to run a bit rich, but that is nothing new. I have a feeling the fuel pump has been getting louder, but I may be imagining it.

Thanks

Z

[gifdy]

Have you got the diagnostic port connector wired into your loom ? If so I could lend you a fault code reader ( the Land Rover one ) if you cover postage. It wont pick up all faults but maybe worth giving it a whirl ?

[z_chromozone]

Thanks for the offer. I will have a look at the loom and see.

How much info can you get out of the device.

Z

[gifdy]

This is a copy & paste from the manual. Gives you an idea :


Code 29 - ECU MEMORY CHECK - If this fault is
detected, all other faults are unreliable and must
therefore be ignored.
‘I ,,
Proceed as follows:
1. Leave battery connected
2. Switch ignition off
3. Wait for approximately 5 seconds
4. Disconnect ECU plug
5. Re-connect ECU plug
6. Switch ignition on and check display unit.
NOTE: If fault code 29 is detected again,
substitute ECU and restart test sequence.
Code 44 - LAMBDA SENSOR A i left bank
Code 45 - LAMBDA SENSOR B - right bank
If one of these fault codes is displayed check the
wiring to that particular lambda sensor.
If both codes are displayed, the volfage supply to
the heater coils of the sensors must be checked.
Refer to Test 26, continuity test procedure.
Code 25 - IGNITION MISFIRE - This code indicates . . . . .
that an ignition system misfire has been detected. I
Codes 40 or 50 indicate on which bank the misfire
has occured. ..’ . .,,
1
.,.
ADDITION: SEPT. 89/REVISED: SEPT. 90
FUEL INJECTION SYSTEM
Code 40 - MISFIRE BANK A - left bank
Code 50 - MISFIRE BANK B - right bank
If both fault codes are displayed check the
following components commom to both banks:
Distributor cap
Rotor arm
Coil
Electrical connections
Pick-up (air gap)
Amplifier
Injectors - if code 34 or 36 displayed.
If either fault code 40 or 50 is displayed check
components applicable to the particular bank that
the misfire has occured on:
.
Spark plugs
HT leads
Distributor cap
Injectors - if code 34 bank A or 36 bank 6
displayed.
:.:.y. : .:.:$c.
Code 12 - AIRFLOW METER - Refer to Test 19,
continuity test procedure.
Code 21 - FUEL TUNE SELECT - Identifies that the
tune select resistor is open circuit - Refer to tune
select resistor test.
Code 34 - INJECTOR BANK A - The display will
indicate if the injector/s are causing the engine to
run rich or lean.
If the bank is running rich, check for:-
- faulty injector wiring and connectors
- stuck open injectors
If the bank is running lean, check for:-
- faulty injector wiring and connectors
- blocked injectors
Code 36 - INjECTOR BANK B - As code 34 except
relevant to bank A injectors.
Code 14 - COOLANT THERMISTOR - Refer to Test
14, continuity test procedure.
Code 17 - THROlTLE POTENTIOMETER - Refer to
Test 17, continuity test procedure.
Code 18 - THROlTLE POTENTIOMETER input
high/AIRFLOW METER - low. - Refer to Tests 17,
18 and 19 of the continuity test procedure
Code 19 - THROTTLE POTENTIOMETER input low/
AIRFLOW METER - high. - Refer to Tests 17, 18
and 19 of the continuity test procedure
Code 88 - PURGE VALVE LEAK - Refer to Test 9
and 10 of the continuity test procedure.
Code 28 - AIR LEAK - Check for air leaks in the
following areas.
Hose, air flow meter to plenum
Breather system hoses to plenum
Brake servo hose
Vacuum reservoir hose (fresh air solenoid)
Distributor vacuum advance
Hose, purge valve to plenum
Injector seals
Joint - By pass air valve to plenum
- Plenum chamber to ram housing
- Ram housing to inlet manifold
- Inlet manifold to cylinder head
By pass air valve hose
Code 23 - FUEL SUPPLY - Check fuel system
pressure, Test 20 of the continuity test procedure.
Code 48 - STEPPER MOTOR - Check base idle
speed - see setting procedure. - Refer to Tests 15
and 16 of the continuity test procedure. Check
road speed sensor - Refer to Test 25 of the
continuity test procedure.
Code 68 - ROAD SPEED SENSOR - Refer to Test
25 of the continuity test procedure.
Code 69 - GEARSWITCH - Refer to Test 24 of the
continuity test procedure.
Code 59 - GROUP FAULTS 23/28 - This indicates
that a fault has been registered that is caused by
the fuel supply or an air leak but the exact fault
cannot be identified. Check all items outlined under
code 23 and 28.
Code 15 - FUEL THERMISTOR - Refer to Test 13 of
the continuity test procedure.