andy thompson Posted October 3, 2012 Share Posted October 3, 2012 Big brass thing in the metering unit - I'd ask for another! Doesn't adjust out I'm afraid Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 3, 2012 Share Posted October 3, 2012 Just spoke with Neil and he is adamant the problem is not the thrust washer but has given some advice to look in other areas. He said it is impossible for the thrust washer to cause this as the metering is done in pairs not in 3s :( . Quote Link to comment Share on other sites More sharing options...
andy thompson Posted October 3, 2012 Share Posted October 3, 2012 May have mixed up issues. - worn stop for shuttle so rear three injectors on MU get too much fuel? Quote Link to comment Share on other sites More sharing options...
GT6 M Posted October 3, 2012 Share Posted October 3, 2012 id check the throttles, see if the reasare opening as much as fronts.also rear cyls can run rich at idle, as the air holes are gunked up wid sludgey oil slowly setting hard over time,than dropping off /moving, then clogging the idle holes upone thing that can mek one set run rich, but its got to be a fluke, is all the one way seals have gon . had one go now and then but not 3 on a set.this will lead it to inject all the time.have a ratch thru here, find thiese pages, most intrestinghttp://cmtk3.webring.org/l/rd?ring=triumphautos;id=121;url=http%3A%2F%2Fwww.lucasinjection.com%2FM Quote Link to comment Share on other sites More sharing options...
GT6 M Posted October 3, 2012 Share Posted October 3, 2012 this what i was on aboot above3. Overfuelling on one or more cylinders (i) Damaged grommet seals between nose of outlet connection and sleeve, allowing unmetered fuel to enter the injector line or lines giving continuous injection. On “Banjo” type outlets this can also occur if the inner ‘0’ ring on the “Banjo” is damaged.its on page 14.M Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 4, 2012 Share Posted October 4, 2012 A few things to check there in the morning.If I was getting continuous injection, I'd see that when I pulled n injector out wouldn't I?All I'm seeing is a regular spurt of fuel on each injection pulse. Quote Link to comment Share on other sites More sharing options...
andy thompson Posted October 4, 2012 Share Posted October 4, 2012 The shuttle in the body is moving too far for the rear cylinders and hence metering a percentage more fuel than the front threeNeil is right - they work in pairs1 and 6 , 2 and 5 , 3 and 4 Are the three rear obviously sooty and the front three obviously lean? Markus is right that there is generally a progression of lean to rich front to back but there is also a fault condition where the difference is not progressive. I have not seen it personally but Andy Roberts (2000 register PI guru) saw the problem on a few PI's Is the air filter new? Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 4, 2012 Share Posted October 4, 2012 Yes, 1, 2 and 3 are obviously lean and 4. 5 and 6 are very sooty. The air filter isn't new but not very old either. If the air filter was old and clogged I could understand them all being rich but it's just the rear 3 cylinders. I wouldn't say the difference is progressive as its quite a marked difference between the first 3 cylinders and the rear 3. I'll take the car for a spin this morning and try to post some photos of the plugs later. Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 4, 2012 Share Posted October 4, 2012 Yes, 1, 2 and 3 are obviously lean and 4. 5 and 6 are very sooty. The air filter isn't new but not very old either. If the air filter was old and clogged I could understand them all being rich but it's just the rear 3 cylinders. I wouldn't say the difference is progressive as its quite a marked difference between the first 3 cylinders and the rear 3. I'll take the car for a spin this morning and try to post some photos of the plugs later. Quote Link to comment Share on other sites More sharing options...
andy thompson Posted October 4, 2012 Share Posted October 4, 2012 You need to explain this to Neil. It is a known problem - I just can't explain the exact detail - its to do with parts shown here http://www.lucasinjection.com/TECH.htm Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 4, 2012 Share Posted October 4, 2012 I've checked the throttle valves and they are sucking more or less the same amount of air accross the rev range. I've set the mixture adjustment screwws in line with what Neil has suggested, put a new set of plugs in and went for a 10 mile drive.After a couple of miles, the car was clearly running rich and I disconnected the big hose to the plenum chamber to negate any effects of the air filter. Here are the plugs after the run. Quote Link to comment Share on other sites More sharing options...
JohnD Posted October 4, 2012 Share Posted October 4, 2012 Is that 1-6 from left to right, or the other way around?If the first, then as said above, the fuelling is working in pairs, 1&2, 3&4 , 5&6, but not from the metering unit, that goes 1/6, 2/5, 3/4.This has been alleged to be due to the size of the plenum tube, which is too small, so that the earlier cylinder on the block 'rob' the later ones of air, so that the back bores run richer on the same amount of fuel injected. I cured this by building a bigger plenum: Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 4, 2012 Share Posted October 4, 2012 Looking at the photos again, I don't think it is clear just how white 1 2 and 3 are. I'm convinced this isn't just the plenum problem. Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted October 4, 2012 Share Posted October 4, 2012 I seriously doubt there is ever a plenum issue on anything except a high spec race engine at full chat.Nick Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 4, 2012 Share Posted October 4, 2012 Many thanks for all the input from everyone. Neil very kindly has supplied another metering unit and the car is 100 percent improved. The air fuel meter is showing tolerable numbers, if anything a bit lean under all conditions except overun when the air fuel meter drops to 10.With a running car I'm not going to do any more "tuning". Lets see how it goes on the run.Ive yet to get the plugs out - the car is still too hot for that. Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 4, 2012 Share Posted October 4, 2012 Got plugs out. Can confirm all 6 cylinders are running lean but not as lean as earlier. We shall see how we go. Quote Link to comment Share on other sites More sharing options...
andy thompson Posted October 4, 2012 Share Posted October 4, 2012 Nice one! Well done to Neil and you... Did he elaborate on the potential cause? Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 5, 2012 Share Posted October 5, 2012 Neil is very interested to identify the cause of this issue as he couldn't imagine how a metering unit issue would cause these symptoms. I'm dropping the unit off with him for him to do his checks. What I can say is that the car has never run as well as it is now with the previous MU. Quote Link to comment Share on other sites More sharing options...
Eagerbeaver Posted October 9, 2012 Share Posted October 9, 2012 Well, here is the post RBRR report. We had got as far as Blyth when the car developed a serious misfire. A compression check showed very little compression on number 1, all others about 14/15 bar. A few more checks confirmed that burnt valves on that cylinder were likely. Until this is fixed I'm not sure if any air fuel guage figures count for anything. I suspect that the initial problem developed with the first MU. The car idles with an A/F of about 11.6. It accelerates at about 12.4. It cruises at low speed at about 15-16 and about 13 at 70. It is at about 10-11 on overrun. I guess I need to sort the head before doing anything else. RBRR was fantastic by the way. Tim Bancroft and the rest of the organisers/marshalls/supporters/entrants all deserve much praise. Quote Link to comment Share on other sites More sharing options...
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