very sick wedge
Discussion
Help please i was driving my wedge on Friday when she suddenly stopped firing . No nasty mechanical noise except a couple of backfires (unburnt fuel in exhaust i suspect)Got the breakdown people out but they could not start her. She is now home and i am trying to get her sorted . Things i have tested,
1) good spark will jump at least 1"
2) about 30 psi fuel pressure in the injector rail which holds when fuel pump is off
3) put a noid? light on the injector connector and it pulses ok
4) rocker cover off and valves move ok and are both closed when piston at tdc
5) rotor arm turning under cranking
6) sprayed easystart into plenum chamber under cranking not even the slightest sign of firing
7) went through the tvrwedgepages fault finding of a 4CU ECU everything seems ok ie throttle pot resistance, air flow meter resistance, coolant temp, air temp, negative coil signal to ecu etc
8) compression test 150psi on a cold engine
The only thing that seems odd is i have taken off the pipe from air flow meter to plenum , put my hand over the plenum hole and under cranking there does not seem to be an awful lot of vacuum there.
The other thing that i cant understand is the neg wire from the coil sends a timing pulse to the ecu to give information as to when to fire the injectors and engine speed however how does the ecu know which injector to fire as there is no crank sensor.
Full details of the car is 3.9 litre rover v8 piper 285 cam jag air flow meter jag injectors mark adams modified tornado 4CU ecu.
One thing that has occurred to me is that there is a vernier timing sprocket fitted and was wondering if this had slipped so throwing off the valve and ignition timing but i would have thought she would still fire up even though running like a bag of bolts.
Even though i consider myself to be a very competant mechanic/electrician this has me totally dumbfounded as well as the technicians at the local volvo franchise (my wife works there)
Sorry if this was a bit long winded but the more info the better i reckon
Any help would be greatly appreciated
1) good spark will jump at least 1"
2) about 30 psi fuel pressure in the injector rail which holds when fuel pump is off
3) put a noid? light on the injector connector and it pulses ok
4) rocker cover off and valves move ok and are both closed when piston at tdc
5) rotor arm turning under cranking
6) sprayed easystart into plenum chamber under cranking not even the slightest sign of firing
7) went through the tvrwedgepages fault finding of a 4CU ECU everything seems ok ie throttle pot resistance, air flow meter resistance, coolant temp, air temp, negative coil signal to ecu etc
8) compression test 150psi on a cold engine
The only thing that seems odd is i have taken off the pipe from air flow meter to plenum , put my hand over the plenum hole and under cranking there does not seem to be an awful lot of vacuum there.
The other thing that i cant understand is the neg wire from the coil sends a timing pulse to the ecu to give information as to when to fire the injectors and engine speed however how does the ecu know which injector to fire as there is no crank sensor.
Full details of the car is 3.9 litre rover v8 piper 285 cam jag air flow meter jag injectors mark adams modified tornado 4CU ecu.
One thing that has occurred to me is that there is a vernier timing sprocket fitted and was wondering if this had slipped so throwing off the valve and ignition timing but i would have thought she would still fire up even though running like a bag of bolts.
Even though i consider myself to be a very competant mechanic/electrician this has me totally dumbfounded as well as the technicians at the local volvo franchise (my wife works there)
Sorry if this was a bit long winded but the more info the better i reckon
Any help would be greatly appreciated
jwt666 said:
The other thing that i cant understand is the neg wire from the coil sends a timing pulse to the ecu to give information as to when to fire the injectors and engine speed however how does the ecu know which injector to fire as there is no crank sensor.
The Range Rover has a cam sensor......you could check the plug.Although you sprayed ether, so it should have hit once.
Best I can offer sorry.
What about the coolant temperature sensor? Haven't spotted this on the list.
When mine was gone it wouldn't run due to massive overfuelling.
Shorting the lead to the sensor out can give you a quick test (ECU signal as for a hot engine), but it can start and run ok (got me home once ...)
Rob
When mine was gone it wouldn't run due to massive overfuelling.
Shorting the lead to the sensor out can give you a quick test (ECU signal as for a hot engine), but it can start and run ok (got me home once ...)
Rob
It is on the list under number 7 but yes short it out for a double-check.
The injector banks do alternate firind but it isn't particularly synced to the firing order, the fuel just sits around until it's needed.
The injectors might be pulsing but at what mark/space ratio? When cranking you don't need much fuel, and massive overfuelling will cause it not to start. Are the plugs wet with fuel?
The injector banks do alternate firind but it isn't particularly synced to the firing order, the fuel just sits around until it's needed.
The injectors might be pulsing but at what mark/space ratio? When cranking you don't need much fuel, and massive overfuelling will cause it not to start. Are the plugs wet with fuel?
jwt666 said:
The other thing that i cant understand is the neg wire from the coil sends a timing pulse to the ecu to give information as to when to fire the injectors and engine speed however how does the ecu know which injector to fire as there is no crank sensor.
It alternately fires the four injectors on each cylinder bank so it does not need to be timed against cylinder/valve position. Have you checked the resistor conections from the box on top of the n/s wing [that where mine is]supplies fuel to injectors, mine had stopped one bank of cylinders due to be needing cleaned inside the connections and tightened slightly to give better fit.
This was only two weeks ago [ran like a bag of spanners ] sorted that and now running sweet even been to BNG.
Hope this might be of some help.
This was only two weeks ago [ran like a bag of spanners ] sorted that and now running sweet even been to BNG.
Hope this might be of some help.
Hi all happy bunny again . Had to go back to basics took rocker cover off concentrated on no2 cylinder . Rotated engine by hand inlet valve shuts then continued to tdc followed lead back to cap took cap off and guess what rotor 90 degrees out!!!!! Pulled dizzy out and found stripped gears it must have jumped out and then remeshed out of sync.
No wonder she would not fire up. New parts picked up and hopefully fitted weekend.
Cheers for all the replies / suggestions.
No wonder she would not fire up. New parts picked up and hopefully fitted weekend.
Cheers for all the replies / suggestions.
The dizzy gear drives the oil pump too which adds extra loading to the gears. If it strips you lose oil pressure, and normally your engine will stop as you have found due to no spark, but if you've replaced the ignition system and dizzy with something electronic then it will continue to run and then trash all the bearings (eh, Tony...)
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