One plug whiter than the rest?
Discussion
When I checked my plugs last night, the plug in No 4 cylinder was whiter than the rest? That said.. the rest only showed a bit of light greying usually on one side only… but No4 showed nothing?
I’ve done the plugs on the car a number of times now and it’s always the same?... I’m told it could be down to the trumpet position in the Plenum.. has anyone else experienced No4 running a tad leaner than the rest??
Another factor here is that when I compression test the pot’s.. they all sit around 14 bar… but No 4 is lower and comes in at 13.5 bar…. Again, I’ve put this down to air flow but my initial readings were done as a std car.. since then I’ve done the trumpet base, plenum spacer, bigger injectors etc so thought it may change the flow into this area. I’ve also have 2 cam’s in it and set back up so don’t think it’s a tight valve as I asked Rob (V8D) to check it last time and he said it was fine?...
May be I need to do a leak down test on this cylinder to see if it’s losing a bit of compression (or this is all it achieves)… I know 0.5 bar is well within the limits of cylinder variation…. But do you think this could be causing the plug to run lean / hot?... If it was lack of air you’d think it would over fuel this pot a tad??.. Any thoughts.. Cheers
I’ve done the plugs on the car a number of times now and it’s always the same?... I’m told it could be down to the trumpet position in the Plenum.. has anyone else experienced No4 running a tad leaner than the rest??
Another factor here is that when I compression test the pot’s.. they all sit around 14 bar… but No 4 is lower and comes in at 13.5 bar…. Again, I’ve put this down to air flow but my initial readings were done as a std car.. since then I’ve done the trumpet base, plenum spacer, bigger injectors etc so thought it may change the flow into this area. I’ve also have 2 cam’s in it and set back up so don’t think it’s a tight valve as I asked Rob (V8D) to check it last time and he said it was fine?...
May be I need to do a leak down test on this cylinder to see if it’s losing a bit of compression (or this is all it achieves)… I know 0.5 bar is well within the limits of cylinder variation…. But do you think this could be causing the plug to run lean / hot?... If it was lack of air you’d think it would over fuel this pot a tad??.. Any thoughts.. Cheers
Mark Adams told me if you get an injector that does not atomise the fuel correctly the fuel stream can effectively wash the plug tip, so the colour is incorrect. Thats how he picks up cars that have fouled injectors before remapping. Worth a bottle or two of injector cleaner methinks.
TBH I've never had much joy from bottled cleaner but getting injectors cleaned and re-furbed certainly works, cost me £12 an injector on the little old Pug, can't think it would be much different for the Griff (apart from twice as many to do!).
This is who I [url]used|http://www.injectorcleaning.co.uk/index.htm[url] and they came with before and after info as well.
Rob
This is who I [url]used|http://www.injectorcleaning.co.uk/index.htm[url] and they came with before and after info as well.
Rob
Yes.. but it did it with the green top's.. and now with my new red top's.. .Can only be the cylinder in some way.. I don't use oil or presurise the crank case so may be a valve holding open a bit some how.. It's not getting worst so not an issue..... may be this is the shunting problem.. allowing it to push back up the inlet when it's closed (only joking.. I'm sure it would take a lot more than this!).. I've had petrol in the inlet with the valve closed and it's stopped there?.. yet another strange one?
Will do may be this winter at some point (no time now!!).. but what's the chances of that?.. geting an existing injector and a new injector both faulty in the same cylinder?.. Mind you... what about the connector and wireing to that injector.. could something be addrift there?? May be there is a Ohm measurement for these back to the ECU or where ever they go?.. Or at least I can see if it's the same as the rest??
Swapping connectors over on the even bank is a doddle 
Note how 3456 are bunched, 4 starts off that packed sequenced and 365 follow closely... I'm convinced slightly uneven lengths to account for path complexity, stolen air, inertia/momentum of air are just as key as the simplified 'equal lengths' to performance & harmonics..
Note how 3456 are bunched, 4 starts off that packed sequenced and 365 follow closely... I'm convinced slightly uneven lengths to account for path complexity, stolen air, inertia/momentum of air are just as key as the simplified 'equal lengths' to performance & harmonics..
You can do a resistance check across the injectors once they are unplugged, and simply compare them, although a simple ohms check will only tell you the injector coil is in one piece, nothing about the fuel flow or mechanics inside. All the injectors simply have 12 volts on one side with the ignition on, and then the ECU fires each bank of 4 injectors at the same time by switching the other side of the injector to ground when needed, so you would get the same signal across all 4 assumming its still connected. I did not fully understand what Spend was getting at, but I can agree that without lambda feedback the two sides of the V8 have slightly different fuelling, but I dont know why. You can get a steam clean effect in the combustion chamber with small leak in the head gasket, and the water level would drop over time.
blitzracing said:
You can do a resistance check across the injectors once they are unplugged, and simply compare them, although a simple ohms check will only tell you the injector coil is in one piece, nothing about the fuel flow or mechanics inside. All the injectors simply have 12 volts on one side with the ignition on, and then the ECU fires each bank of 4 injectors at the same time by switching the other side of the injector to ground when needed, so you would get the same signal across all 4 assumming its still connected. I did not fully understand what Spend was getting at, but I can agree that without lambda feedback the two sides of the V8 have slightly different fuelling, but I dont know why. You can get a steam clean effect in the combustion chamber with small leak in the head gasket, and the water level would drop over time.
Okay... so have compression tested again tonight and they are all on 14 bar. (5 turns of the crank).. and no.. I don't have a leak as I know to the mm where my water level is...When I was talking about the injector and connector... I ment more the wire going to No4 injector... could this be a bit duff?... at the old injector did it in No4 and the new one does it in No4... the only common denominator being the wire to the injector, the cylinder (now ruled out) and also may be the plug extender which I'll now move to another plug...
I think what Spend was saying in the last bit anyway, was that air flow in the plenum is not a straight forward thing... and if the air flow to No4 trumpet is differant to the rest.. this could change it's fueling... thats what others have said also...It may be getting more air or being robbed by the ones next to it.. Thats why i asked if anyone else had seen this.. as it would be a common thing (unless my engine fires in a difo order to std)
.
One thing I'm not up on is this 'bank' fireing of injectors... are you saying that the ECU fires 4 injectors at a time every time... so per cylinder it get's 4 shots for 1 opening of the valve? (or every 2 rev's)... I have seen referance to this before but not fully understood it (simpleton you know)... So if that is the case I can swap the wire from No4 onto another injector and see if that plug becomes white?... so is it banks that fire together ie Left and Right... or a group of 4 on both banks and then another group of 4?
Sorry for being thick and if I've totaly got it wrong... please don't shout!!
Cheers
Some folks have even been known to cross the injector wiring across different banks even. Cliffs 360 exhaust literally demands it as one example IIRC.
If there is a fault in the wiring/connector swapping the plugs between 2 injectors and seeing if the problem moves pots is a common quick check, I didn't think it needed spelling out.
If there is a fault in the wiring/connector swapping the plugs between 2 injectors and seeing if the problem moves pots is a common quick check, I didn't think it needed spelling out.
Thanks Guy's... I'll give it a go with No6.. see if it moves down?....
I have seen post on this but the penny didn't drop exactly what they were on about obviously... May be because it's a very crude way of doing it ins't it?.. Must say, I'd always assumed that the injectors only fired as the inlet valve was opening and once per cycle... but as you say.. 2 outputs.. how can they ... dough!!
So going on from this.. and I suppose this is why after market ECU's have trigger wheels and crank sensors etc. .. But how does the Lucas ECU know where the engine is.. from what your saying and from what I know about sensors (or lack of them on the engine) it doesn't know at all where it is... Just the RPM... so even as they fire in banks (Left and Right).. You could actualy mix the lot up using some left on the right bank and so on... and be no worst off? Is this correct?
Wow... Now I see why after market ECU's tend to be better here... do these work on the one shot per cycle basis as was my initial thoughts on the existing?....
Cheers....
I have seen post on this but the penny didn't drop exactly what they were on about obviously... May be because it's a very crude way of doing it ins't it?.. Must say, I'd always assumed that the injectors only fired as the inlet valve was opening and once per cycle... but as you say.. 2 outputs.. how can they ... dough!!
So going on from this.. and I suppose this is why after market ECU's have trigger wheels and crank sensors etc. .. But how does the Lucas ECU know where the engine is.. from what your saying and from what I know about sensors (or lack of them on the engine) it doesn't know at all where it is... Just the RPM... so even as they fire in banks (Left and Right).. You could actualy mix the lot up using some left on the right bank and so on... and be no worst off? Is this correct?
Wow... Now I see why after market ECU's tend to be better here... do these work on the one shot per cycle basis as was my initial thoughts on the existing?....
Cheers....
spend said:
Lucas doesn't know where the engine is, just how fast it is spinning - sharing a signal from the coil with the rev counter.
Many of the alternate ECU's still only support banked/batched injection. Thats a whole thesis in itself....
Indeed.. just been reading the Omex and MegaSquirt info.. Very interesting.... But I need to avoid it!.. I'm sure it could take over your life!!!Many of the alternate ECU's still only support banked/batched injection. Thats a whole thesis in itself....
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