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big ives



Member Since: 24 Dec 2013
Location: Northern Ireland
Posts: 113

United Kingdom 
V8 3.9EFI appears to mis fire

After a full upgrade and service on my V8 3.9EFI electrical system which was completed yesterday I took it for a test drive, everything was working fine except when I press the accelerator hard the engine lets say at about 50mph it appears to be running on 7 cylinders, no mis fire just loss of power/shudders until I back off on the throttle.
If I press the accelerator slowly, I can get to above 70mph no problems.

The engine was running ok before I upgraded the system, had a valley gasket leak, yes running rich, yes sometimes hard to start cranking over a long time, so hence the upgrades and service, but once started ran like a dream.

Engine oil and filters changed every 3000miles
New valley gasket (Just for info)
New steering pump (as I had the front stripped)
New fuel pressure unit and all set to the correct PSI
New in tank fuel pump, all new filters on the fuel system
New distributor, complete with new cap and rotor from RPI
New spark plugs NGK BPR6ES
New RPI amp, plus Bosch coil
New temp coolant sensor
New magncour leads

Timing set at 6degrees BTDC, and set up with a timing light, with vacuum hose disconnected in fact set up several times as I wasn’t happy with the first set up.

Base idle set with vacuum hoses blocked, 570rpm on the Rovergauge on the laptop, when vacuum hoses connected RPM is then sitting at 770rpm which sounds nice

No fault codes on the Rovergauge software when driving.

MAF out put voltages are ok as per diagnostic info found on this web site, and set at 1.5v due to the Adams ECU remapped.

TPS output voltage was high so I set the voltage as per the instructions, THIS was done last month before I changed all the parts. I plan to test voltage and adjust tomorrow but not sure if this is the fault?

After reading the long story above can anyone shed some light on my next course of action?

many thanks for any help........cheers Ives 2016 Discovery 4
1989 90 CSW V8 (fully rebuilt and running like a dream)
1996 defender tray back fully rebuilt/loaded for challenge events

Post #803382 24th Nov 2019 10:31am
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ARC99



Member Since: 19 Feb 2013
Location: North Yorkshire
Posts: 1831

United Kingdom 2008 Defender 110 Puma 2.4 USW Cairns Blue

Had a similar problem years ago when I owner a RR and I asked the local stealer to set the engine up for unleaded petrol.
It ran sweet on the test drive, the next day I collected my caravan as I was due to go away, the RR struggled to pull the caravan up a slight hill only managing 20mph.

To cut a long story short. After the garage ran up a £6.000.00 bill which they expected me to pay and six months later I took it to a specialist tuner who had a 4x4 rolling road they found that the distributor was 180 degrees out. Don't make old people mad.
We don't like being old in the first place,
so it doesn't take much to Censored us off.

Richard

Post #803385 24th Nov 2019 10:57am
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big ives



Member Since: 24 Dec 2013
Location: Northern Ireland
Posts: 113

United Kingdom 

Arc99
when i set the timing i was sacred it would be out 180 degrees, so i removed the rocker cover twice and checked that No1 valves where closed and no tension on the springs.

i marked the TDC on the fly wheel and installed the distrubuitor and connected everything and she started ok
howvever this was last month and as i opened and serviced the distrubuitor however rebuilting it i damagaed the springs on the bob weights which when fitted i knew it was no good as i could here a noise.

i got a price to rebuild my old Lucas 35dms but the cost was way way more than a new one from RPI, so i bought a new distrucitor and fitted it yeserday at the same marks on the fly wheel and as i said she runs sweet.

maybe i need to recheck the TDC again for the new distrubitor Big Cry Big Cry Big Cry 2016 Discovery 4
1989 90 CSW V8 (fully rebuilt and running like a dream)
1996 defender tray back fully rebuilt/loaded for challenge events

Post #803386 24th Nov 2019 11:21am
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oneten110



Member Since: 02 Jul 2011
Location: Wish I was still in France
Posts: 741

United Kingdom 

At any point during all the work did you have the injectors serviced or cleaned? It is not a Defender, it is a One_Ten

Post #803423 24th Nov 2019 8:20pm
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big ives



Member Since: 24 Dec 2013
Location: Northern Ireland
Posts: 113

United Kingdom 

oneten

no not serviced or cleaned

had them out when i replaced the valley gasket but that was a month or so back, she has been driven since then 2016 Discovery 4
1989 90 CSW V8 (fully rebuilt and running like a dream)
1996 defender tray back fully rebuilt/loaded for challenge events

Post #803425 24th Nov 2019 8:37pm
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rallysteve



Member Since: 10 Feb 2014
Location: South Yorks
Posts: 1656

United Kingdom 1984 Defender 90 V8 Petrol PU Caledonian Blue

Have you checked that the vacuum advance operates correctly (you can suck on the pipe and the idle speed should change and it hold a vacuum)

Steve 02' 110 TD5 Double Cab Rebuild Thread
84' 90 3.9 V8 Caged Pickup Build Thread


Mobile Diesel Heater Build Thread

Post #803433 24th Nov 2019 9:22pm
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big ives



Member Since: 24 Dec 2013
Location: Northern Ireland
Posts: 113

United Kingdom 

rallysteve

its a new dizzy, so no i didnt suck on the vacuum hose, but will check tomorrow 2016 Discovery 4
1989 90 CSW V8 (fully rebuilt and running like a dream)
1996 defender tray back fully rebuilt/loaded for challenge events

Post #803434 24th Nov 2019 9:31pm
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rallysteve



Member Since: 10 Feb 2014
Location: South Yorks
Posts: 1656

United Kingdom 1984 Defender 90 V8 Petrol PU Caledonian Blue

Worth checking as it can lead to very flat acceleration.

Is it serpentine or pre-sepentine? Worth whipping out plug number 1 and checking that the TDC mark is actually at TDC. Mine was quite a bit out which meant the 8deg timing i had set was way off.

Steve 02' 110 TD5 Double Cab Rebuild Thread
84' 90 3.9 V8 Caged Pickup Build Thread


Mobile Diesel Heater Build Thread

Post #803438 24th Nov 2019 9:45pm
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big ives



Member Since: 24 Dec 2013
Location: Northern Ireland
Posts: 113

United Kingdom 

rallysteve

pre-sepentine

as i said twice i checked the TDC by removing rocker cover and removing No1 to find TDC

going to re-check everything again 2016 Discovery 4
1989 90 CSW V8 (fully rebuilt and running like a dream)
1996 defender tray back fully rebuilt/loaded for challenge events

Post #803442 24th Nov 2019 10:15pm
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rallysteve



Member Since: 10 Feb 2014
Location: South Yorks
Posts: 1656

United Kingdom 1984 Defender 90 V8 Petrol PU Caledonian Blue

Apologies missed that post about the timing Embarassed

Steve 02' 110 TD5 Double Cab Rebuild Thread
84' 90 3.9 V8 Caged Pickup Build Thread


Mobile Diesel Heater Build Thread

Post #803445 24th Nov 2019 10:32pm
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big ives



Member Since: 24 Dec 2013
Location: Northern Ireland
Posts: 113

United Kingdom 

rallysteve

no problem Rolling with laughter Rolling with laughter Rolling with laughter Rolling with laughter

i just cant figure out whats wrong, will try again and revert with any change 2016 Discovery 4
1989 90 CSW V8 (fully rebuilt and running like a dream)
1996 defender tray back fully rebuilt/loaded for challenge events

Post #803449 24th Nov 2019 11:02pm
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big ives



Member Since: 24 Dec 2013
Location: Northern Ireland
Posts: 113

United Kingdom 

wee update
today removed the rocker cover and No1 plug rechecked timing marks TDC ok same as I had the last three times.
removed the new dizzy and repositioned so the rotor arm was at the 5 oclock position.
with dizzy out checked vacuum on the advance working as expected (new dizzy)
checked plugs and leads all ok, should be only a few hundred miles on them
reset base idle, rechecked the fuel pressure regulator (adjustable unit) set to 40psi with ignition on, drops to 34psi with engine running, stay at 34psi for a long time after the engine is stopped
checked output on TPS which was a bit low 0.189v?? I had set t before to 0.354v, set back to above 0.50v
checked all ignition wires to coils etc and renewed and crimped what was needed.
set timing to 9 degrees BTDC

test run and drove her hard, the misfire or hesitating on full throttle not as bad as the other day, 99% better but as I have OCD I need to get her to 100% but that’s for another day Whistle Whistle

fitting a new LOF powerspec clutch and master cylinder tomorrow, oh the joys of owning a landrover Laughing Laughing

thanks for everybody’s input Thumbs Up Thumbs Up 2016 Discovery 4
1989 90 CSW V8 (fully rebuilt and running like a dream)
1996 defender tray back fully rebuilt/loaded for challenge events

Post #803507 25th Nov 2019 5:44pm
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big ives



Member Since: 24 Dec 2013
Location: Northern Ireland
Posts: 113

United Kingdom 

now running like a dream Very Happy Very Happy Very Happy Very Happy 100%, fires up on the first tuen of the key
set TPS back to 0.315v
serviced and rebuilt my old lucas dizzy and installed
re-set timing to 10 degress BTDC
re-set base idle

happy days until the next issue Whistle Whistle Whistle 2016 Discovery 4
1989 90 CSW V8 (fully rebuilt and running like a dream)
1996 defender tray back fully rebuilt/loaded for challenge events

Post #805356 8th Dec 2019 6:23pm
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