Running Lean / Running Rough
Discussion
Hi all, as above
These are the right side NGKs B7EC S. Note how lean the centre 2 are !!
She started running lumpy last w end, it's as if she's stumbling / missing around 2 - 2,500 rpm. Done it before a couple of years ago, then cleared.
The centre 2 plug tops and the leads have a white powdery coating of corrosion, which I've sprayed with cleaner. Could this be causing the rough running ?
These are the right side NGKs B7EC S. Note how lean the centre 2 are !!
She started running lumpy last w end, it's as if she's stumbling / missing around 2 - 2,500 rpm. Done it before a couple of years ago, then cleared.
The centre 2 plug tops and the leads have a white powdery coating of corrosion, which I've sprayed with cleaner. Could this be causing the rough running ?
Edited by neutral 3 on Monday 13th July 16:21
Right bank Plugs re fitted, checked the left bank lead / plug tops and no visible corrosion. Fired the beast up and it's running lumpy.
Set off and the systems are still there. Do about 4 miles and it's getting worse. Get back and it's struggling to idle. Open the bonnet and my ruddy Steve Heath bonnet props mount has disapeared back up the road somewhere !
Engine dies and now won't re start.
I'm thinking ignition coil breaking down ? Or fuel pump ( the original one ) but fuel pump is priming when imobilser is pressed.
Any ideas anyone ? My 98th birthday on thurs and I want to drive it !!
Set off and the systems are still there. Do about 4 miles and it's getting worse. Get back and it's struggling to idle. Open the bonnet and my ruddy Steve Heath bonnet props mount has disapeared back up the road somewhere !
Engine dies and now won't re start.
I'm thinking ignition coil breaking down ? Or fuel pump ( the original one ) but fuel pump is priming when imobilser is pressed.
Any ideas anyone ? My 98th birthday on thurs and I want to drive it !!
The corrosion certainly won't help
Could be the coil or amp breaking down; does it restart once it has cooled down?
Have you checked for air leaks, around the plenum or the induction hose on the plenum?
It could be any number of things, have you done anything recently before the problem started?
Could be the coil or amp breaking down; does it restart once it has cooled down?
Have you checked for air leaks, around the plenum or the induction hose on the plenum?
It could be any number of things, have you done anything recently before the problem started?
The injector pulse width is the same across all 4 injectors is the same across each side of the V8, so the amount of fuel should be the same and the air feed is also common, so an air leak would show up as all 8 running lean. By running lean what you mean is the carbon is burnt off the plugs due to high temp, but you can also wash the carbon off with un burnt fuel, or water getting in to the combustion chamber from a blown head gasket. Id start with a compression test. If you can get the engine to run, you could also try the trick with of touching a cable tie onto each exhaust header and see if they all melt. A non running cylinders header will be much colder than the others, so you could be looking at gasket or ignition more than fuel.
Pulled the plugs on the left bank earlier and they look similar in color to the ones on the right bank. Span her over on the starter and the left front has a spark.
Cleaned the plugs and put them back in, turned the ignition on, pressed the imobilser fob button and the fuel pump primed. Span her over and won't start !!
Put a spark plug in the right front lead, turned her over on the starter and a very strong spark.
So what's wrong ?
Will have to borrow a compression tester.
Checked 5 of the leads and all have spark. Disconnected then re connected the ECU and the birds nest of wiring and relays in the foot well in case of corrosion.
Batt was very low last night. Re charged it then tried again to start it. Fuel pump is priming and there is fuel in the pipe under pressure, but still won't fire. I'm Completly baffled as to why it won't start.
Towing it round to my garage in the morn for a compression test. Fingers XD it's not head gasket or bent valves !!
Batt was very low last night. Re charged it then tried again to start it. Fuel pump is priming and there is fuel in the pipe under pressure, but still won't fire. I'm Completly baffled as to why it won't start.
Towing it round to my garage in the morn for a compression test. Fingers XD it's not head gasket or bent valves !!
Fuel tank breather blocked ?
fuel line internally collapsed ?
Pressure regulator faulty ? (Don't really know if this is possible...)
Have you done something to the dizzy, check cap and rotor ? leads in correct sequence/firing order ? (just thinking out loud)
Checked induction tract, including plenum and butterfly for anomalies (collapsing/broken/leaking) ?
Bit puzzling this !
(kindly report findings)
Frank
fuel line internally collapsed ?
Pressure regulator faulty ? (Don't really know if this is possible...)
Have you done something to the dizzy, check cap and rotor ? leads in correct sequence/firing order ? (just thinking out loud)
Checked induction tract, including plenum and butterfly for anomalies (collapsing/broken/leaking) ?
Bit puzzling this !
(kindly report findings)
Frank
By the horrible smell of petrol as you crank the engine, or wet spark plugs if you drop one out to have a look. If you want to get technical you need a noid lamp that plugs ontop of the injector and will flash when there is a 12 volt pulse. Its worth checking for the 12 volt supply on the injector rail- if you ground one side of a test meter, and then test the injector connections, one should be at 12 volts if the ignition is on. They do tick lightly as they fire, you might be able to hear it if someone cranks the engine and you hold a screwdriver against your ear and an injector.
Wet plugs is what I thought - if it's been cranking for ages it'll stink or be flooded - if the injectors are actually working.
Has a spark and fuel pump is pumping, what else is there - is there anything ecu related that would keep the injectors shut?
Or am I not only barking up the wrong tree but in the wrong forest
Has a spark and fuel pump is pumping, what else is there - is there anything ecu related that would keep the injectors shut?
Or am I not only barking up the wrong tree but in the wrong forest
Quick update , Just got to the garage, pulled the plugs, but access is so tight to get a compression tester in !
No 4 pot ( right bank ) is showing 120 psi , this is the cylinder with the plug that was very white. And now my year old Halfords battery has expired.....TVRs.....don't you just Love them !
No 4 pot ( right bank ) is showing 120 psi , this is the cylinder with the plug that was very white. And now my year old Halfords battery has expired.....TVRs.....don't you just Love them !
Edited by neutral 3 on Thursday 16th July 11:42
Edited by neutral 3 on Thursday 16th July 12:05
Compressions all tested
No 8 - 215 No 7 - 175
No 5 - 160
No 3 - 158
No 1 - 179
No. 6 - 210
No. 4 -102
No. 2 - 172
4 is very low and this is the cylinder with the plug that was very white in colour. So it's looking like head gasket time, but she should still fire.
Strong smell of fuel when testing the compressions and the comp tester is wet with petrol, so fuel is getting through.
No 8 - 215 No 7 - 175
No 5 - 160
No 3 - 158
No 1 - 179
No. 6 - 210
No. 4 -102
No. 2 - 172
4 is very low and this is the cylinder with the plug that was very white in colour. So it's looking like head gasket time, but she should still fire.
Strong smell of fuel when testing the compressions and the comp tester is wet with petrol, so fuel is getting through.
Low compression on one pot wont stop it running completely- so Id suggest you have more than one fault. To verify the gasket is gone there is a simple test a garage can do to check for exhaust gas in the cooling water, but you will need to get it firing first. Id take two steps backwards in the short term, and get a strobe on number one plug and check its firing at around 8-10' btdc at cranking speed, just to eliminate the unknowns. If the spark is good, you can always try a good squirt of easy start into the plenum, buy removing one of the blanking bolts (if you have any ) or possibly the servo take off, but put it back before you crank it over. Even if the injectors are not opening it should at least fire on easy start.
neutral 3 said:
Compressions all tested
No 8 - 215 No 7 - 175
No 5 - 160
No 3 - 158
No 1 - 179
No. 6 - 210
No. 4 -102
No. 2 - 172
4 is very low and this is the cylinder with the plug that was very white in colour. So it's looking like head gasket time, but she should still fire.
Strong smell of fuel when testing the compressions and the comp tester is wet with petrol, so fuel is getting through.
The garage should know to disconnect fuel and sparks before compression testing. The test should also be done on a hot engine at wide open throttle.Hopefully they knew that.No 8 - 215 No 7 - 175
No 5 - 160
No 3 - 158
No 1 - 179
No. 6 - 210
No. 4 -102
No. 2 - 172
4 is very low and this is the cylinder with the plug that was very white in colour. So it's looking like head gasket time, but she should still fire.
Strong smell of fuel when testing the compressions and the comp tester is wet with petrol, so fuel is getting through.
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