Nick, Your project looks cool! See my comments embedded below. -Joe Kuchan --- In dmcnews@xxxxxxxxxxxxxxx, "Nick" <nicholden@...> wrote: > From a dead cold engine extractor 1 & 2 is getting 200deg c hotter > after just 2 minutes of running at about 1500 rpm. > > Could a lack of air to those two cyclinders be causing excessive > temps? Comment: No. If anything, too much fuel would make them run cooler. BTW, the PRV intake is held on by just four puny 7 mm bolts, and the individual intakes are sealed by o-rings that can easily come out of place when installing the intake. A loose or stripped intake manifold bolt on the passenger front part of the manifold could allow it to admit unmetered air, most of which would go to cylinders 1 and 2. An out-of-place o-ring on cylinders one or two would also prevent the manifold from seating properly. These kinds of defects would likely have been caught by a smoke test, which you said you have done, but not necessarily by a leak-down test since that is done with both valves closed. When you did the smoke test, I assume that you pumped smoke into the intake. Is that correct? Did you watch for smoke leaking out under the intake in the area of cylinders 1 and 2? I can't help but think that the fact that these two cylinders are adjacent is a clue to the problem. Extractor 3 was also slightly dis coloured but not showing the > same excessive temps when running. The way the air enters my manifold > it may be possible it is mainly been directed to the other bank and > starving 1,2 &3. I am at a point now that i have to look at everything. > > The plugs on 1,2&3 would indicate it is not a fuel problem but it did > occasionally blow a flame out of the exhaust on decel. that would > indicate raw fuel in the exhaust. Comment: A flame is pretty extreme, but remember that when the throttle plate slams shut on rapid deceleration, the air flow is cut off nearly completely almost immediately, leaving fuel nowhere to complete combustion except in the exhaust. This is the cause of the cool "popping" sound you hear from performance exhausts during deceleration. A flame indicates excessive fuel in the exhaust, however. > > My theroy is that due to a lack of air in Cyc 1,2 the fuel is not > burning correctly and in the combustion chamber and igniting in the > extractor. Cyclinder 3 is not geeting as hot becasue it is still > getting a small amount of air as it is the first cyclinder on that > bank. > > Any other thoughts and comments are welcome! If several cylinders are running too lean for some reason (bad injectors, wiriung harness problems to the injectors, flase air, or whatever) the lambda probe (O2 sensor) will see that and attempt to make the mixture richer using the frequency valve. Since the DeLorean has just a single O2 sensor watching the ENTIRE motor (Is that still true on your car?) a couple of lean cylinders will make the ECU try to enrich mixture. It can only enrich ALL cylinders, with the result being that if all cylinders EXCEPT 1 and 2 are running normally, then 1 and 2, which are running lean will cause the rest of the motor to run rich. Have you done anything to provide enrichment under boost? If so, what have you done? I think you have an air leak into cylinders 1 and 2. I think the O2 sensor sees this as a lean indication, and is trying to enrich the mixture. The result is that all cylinders except 1 and 2 are running rich, which explains the flame from the exhaust and the higher temps in 1 and 2 than in othger cylinders. What were your temp readings again? If my theory is correct, then all cylinders except one and two will actually be cooler than normal, and while 1 and 2 may be hotter than the others, they will probably not be as hot as they might otherwise be if the lambda circuit were inoperative. Good luck! To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/