V8S Overfueling
Discussion
Hi all, does anyone know a lot about the fuel injection system on the 4.0 V8?
I was out for a run yesterday with some fellow TIV'ers (and a Porsche and a Ferrari) and she was running really well. Any way after a brief stop she was reluctant to start and ran like a bag of nails. Wouldn't rev above 3,500 rpm and pulled like a 2.0 4 cyl.
Hoped that a good thrash would clean it out (ever an optimist) but it got worse and after a mile pulled into a layby to have a look under the bonnet. My mates had seen huge white clouds coming out the back of the car.
One of my mates pointed out a wet patch on the exhaust manifold. Touch and smell said that it was neat petrol. It was weeping out from the manifold gasket on the number 2 cylinder. The smell from the back of the car was fuel vapour coming out of the exhaust even with the engine off.
I tried disconnecting the AFM on the advice of a friend and this made no difference to the rough running.
My strong suspicion is that the injector in number 2 cylinder has jammed wide open squirting loads of neat fuel into, and back out of, the cylinder and down the exhaust. If so then hoping that an injector recon will fix it?
So the question is does this sound feasible and what else could/should I check before I have to give up and get it dragged into a workshop?
Bob
I was out for a run yesterday with some fellow TIV'ers (and a Porsche and a Ferrari) and she was running really well. Any way after a brief stop she was reluctant to start and ran like a bag of nails. Wouldn't rev above 3,500 rpm and pulled like a 2.0 4 cyl.
Hoped that a good thrash would clean it out (ever an optimist) but it got worse and after a mile pulled into a layby to have a look under the bonnet. My mates had seen huge white clouds coming out the back of the car.
One of my mates pointed out a wet patch on the exhaust manifold. Touch and smell said that it was neat petrol. It was weeping out from the manifold gasket on the number 2 cylinder. The smell from the back of the car was fuel vapour coming out of the exhaust even with the engine off.
I tried disconnecting the AFM on the advice of a friend and this made no difference to the rough running.
My strong suspicion is that the injector in number 2 cylinder has jammed wide open squirting loads of neat fuel into, and back out of, the cylinder and down the exhaust. If so then hoping that an injector recon will fix it?
So the question is does this sound feasible and what else could/should I check before I have to give up and get it dragged into a workshop?
Bob
Stuck injector isn't impossible although it seems pretty unlikely.
I'd be more inclined to look for ignition issues first, because they'd produce the same symptoms and they're far more common. To complicate things, now that the plugs have been fouled it's unlikely to run cleanly even if the original problem goes away.
Have you checked the fuel pressure? If the vac line to regulator has fallen off or split, or the regulator itself has failed, the excess fuel will cause flooding under light load (it might run better as you open the throttle). Also check the coolant temp sender. If you suspect an injector has jammed, you can test for that by connecting 12V across the injector and listening for the click as it opens. Note that if the fuel rail is pressurised this can dump a significant amount of fuel into that cylinder - I doubt you'll be worried about that by now, but if you're working on a running engine be sure to depressurize the fuel rail first.
I'd be more inclined to look for ignition issues first, because they'd produce the same symptoms and they're far more common. To complicate things, now that the plugs have been fouled it's unlikely to run cleanly even if the original problem goes away.
Have you checked the fuel pressure? If the vac line to regulator has fallen off or split, or the regulator itself has failed, the excess fuel will cause flooding under light load (it might run better as you open the throttle). Also check the coolant temp sender. If you suspect an injector has jammed, you can test for that by connecting 12V across the injector and listening for the click as it opens. Note that if the fuel rail is pressurised this can dump a significant amount of fuel into that cylinder - I doubt you'll be worried about that by now, but if you're working on a running engine be sure to depressurize the fuel rail first.
GreenV8S said:
Stuck injector isn't impossible although it seems pretty unlikely.
I'd be more inclined to look for ignition issues first, because they'd produce the same symptoms and they're far more common. To complicate things, now that the plugs have been fouled it's unlikely to run cleanly even if the original problem goes away.
Have you checked the fuel pressure? If the vac line to regulator has fallen off or split, or the regulator itself has failed, the excess fuel will cause flooding under light load (it might run better as you open the throttle). Also check the coolant temp sender. If you suspect an injector has jammed, you can test for that by connecting 12V across the injector and listening for the click as it opens. Note that if the fuel rail is pressurised this can dump a significant amount of fuel into that cylinder - I doubt you'll be worried about that by now, but if you're working on a running engine be sure to depressurize the fuel rail first.
Thanks for your post.I'd be more inclined to look for ignition issues first, because they'd produce the same symptoms and they're far more common. To complicate things, now that the plugs have been fouled it's unlikely to run cleanly even if the original problem goes away.
Have you checked the fuel pressure? If the vac line to regulator has fallen off or split, or the regulator itself has failed, the excess fuel will cause flooding under light load (it might run better as you open the throttle). Also check the coolant temp sender. If you suspect an injector has jammed, you can test for that by connecting 12V across the injector and listening for the click as it opens. Note that if the fuel rail is pressurised this can dump a significant amount of fuel into that cylinder - I doubt you'll be worried about that by now, but if you're working on a running engine be sure to depressurize the fuel rail first.
Is there a simple check for the Fuel Pressure regulator failing that I can do at a home mechanic level?
It didn't seem to run any better with some throttle on, wouldn't rev or pull away very well.
Good call on listening for a clicking injector. No worries about dumping fuel now as the engine will be stone cold when I get to her this weekend and any damage must already have been done by now.
I'm also advised to pull the fuel rail out of the heads, with the injectors still attached. Then ignition on to run the fuel pump but without cranking the engine. This should pressurise the fuel rail and cut out the pump with no fuel being passed through the injectors. If one is stuck open then it should spray fuel through continuously.
Might be an idea to put a bucket underneath the fuel rail though.
Phillpot (Mike) has let me have the contact details for a firm he used to clean out his injectors. Price seems reasonable so I might just go ahead and get this done anyway.
Bob
What is the idle like?
I have messed about with the injection system and it is surprising how little effect disconnecting one or two injectors has on the idle speed.
If its idling very rough indeed you could have a bank of injectors down, they are fired in 2 lots of 4, wired to each side of the engine according to the Range Rover Haynes manual.
ECU Pin 11 feeds injectors 2,4,6 & 8 and ECU Pin 13 feeds 1,3,5 & 7.
There is a common to all injectors not sure of this is +12v or Gnd though.
I have messed about with the injection system and it is surprising how little effect disconnecting one or two injectors has on the idle speed.
If its idling very rough indeed you could have a bank of injectors down, they are fired in 2 lots of 4, wired to each side of the engine according to the Range Rover Haynes manual.
ECU Pin 11 feeds injectors 2,4,6 & 8 and ECU Pin 13 feeds 1,3,5 & 7.
There is a common to all injectors not sure of this is +12v or Gnd though.
The idle was as rough as a badgers nether regions, but to be fair it would actually idle on its own. Running at idle produced a large white petrol smelling cloud that obscured the road after about 2 minutes running. Obviously I didn't want it to be running for long the way it was performing.
I suppose that the surprising thing was that the engine was capable of restarting at all.
Bob
I suppose that the surprising thing was that the engine was capable of restarting at all.
Bob
Bobhon said:
I'm also advised to pull the fuel rail out of the heads, with the injectors still attached. Then ignition on to run the fuel pump but without cranking the engine. This should pressurise the fuel rail and cut out the pump with no fuel being passed through the injectors. If one is stuck open then it should spray fuel through continuously.
Be EXTREMELY careful if you do that. You'll be dealing with petrol under pressure, and no matter how carefully you try to contain the petrol the injector will create a lot of petrol vapour. Combine that with wires being connected / disconnected to power the injectors (which are inductive so tend to make a nice big spark when you disconnect 'em) and you have all the ingredients for a nice big fireball. I suggest you leave the fuel rail and injectors on the car and concentrate on finding out whether the injectors are making clicking noises when you operate them. If they all are then it seems unlikely that any of them are leaking enough to produce the symptoms you're describing. (It's a known problem for dirty injectors to fail to close fully, but that typically produces a tiny weep of petrol and not enough to affect the way the car drives. If it's an injector fault you're looking for an injector stuck open, which by my guess would dump enough fuel into the bore during starting/idling to hydraulic lock it. Bottom line, I think you're barking up the wrong tree looking for an injector fault. You might need to go there in the end, but it's not where I'd start.So with some telephone help from Craig at Dyno Torque the fault was diagnosed last weekend as a sticking open injector on number 4 cylinder. Craig seems to have a lot of knowledge on Rover V8's and he says that he's seen this fault before, usually the over fueling causes a hydraulic lock in the engine, bending a con rod and generally toasting the engine. 
But mine didn't actually stop so it looks as if I've gotten away with it.
So I dropped the car off with him today (surprising how well it runs on only 7 cylinders with the No4 injector disconnected). It's having a recon injector fitted, an oil leak cured and the oil and filter changed (petrol in the sump).
Speaking with Craig he seems to specialise in LS conversions to the car of your choice. He's showing a couple of LS Cerbies and an LS Saggy on his website.
Looking to get the car back this time next week and I'll let you know how it goes.
Bob
But mine didn't actually stop so it looks as if I've gotten away with it.
So I dropped the car off with him today (surprising how well it runs on only 7 cylinders with the No4 injector disconnected). It's having a recon injector fitted, an oil leak cured and the oil and filter changed (petrol in the sump).
Speaking with Craig he seems to specialise in LS conversions to the car of your choice. He's showing a couple of LS Cerbies and an LS Saggy on his website.
Looking to get the car back this time next week and I'll let you know how it goes.
Bob
So a quick update. Craig found that the cam was also knackered with one exhaust lobe being pretty round, not good. Decided to replace it with a new MC1 cam.
Picked the car up today and it drove sweet as a nut. Far more power and torque right through the rev range. Pulls like a train and rapidly whistles up to the national speed limit... where permitted.
It even politely span its wheels on an upchange into second gear, lovely.
Seems to run a bit more like I expected a 4.0 litre to.
Looking forward to taking it out for more of a run soon.
Needs a new battery though as the old one is struggling a bit to hold its charge. Off to Halfords with the trade card to spend some more money then.
Bob
Picked the car up today and it drove sweet as a nut. Far more power and torque right through the rev range. Pulls like a train and rapidly whistles up to the national speed limit... where permitted.
It even politely span its wheels on an upchange into second gear, lovely.
Seems to run a bit more like I expected a 4.0 litre to.
Looking forward to taking it out for more of a run soon.
Needs a new battery though as the old one is struggling a bit to hold its charge. Off to Halfords with the trade card to spend some more money then.
Bob
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