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Wideband and launch control question.
Posted: Wed Jul 19, 2006 9:13 pm
First of all, I finally got my s300 working after two ecu's. When i have my launch control set, and i'm using it, my wideband which is not yet hooked up through the hondata, will read very lean while launch control is being used. I don't understand if that is because the hondata cuts fuel, if so, isn't that bad if ur at full throttle, wouldn't that cause the egt's to climb dangerously, I don't want to mess anything else up. Also I want to hook up my innovative lm-1 wideband through the system. I have heard of people hooking it up to the eld, which is very vague to me. Do they leave the factory o2 hooked up, or does it get disconnected. Also do u feed a narrow band signal to the hondata, or do u feed a lambda signal to the wideband. Either way any help would be appreciated, I want to make sure I do this right. Thanks everyone. :)
Posted: Thu Jul 20, 2006 9:37 am
Revlimits can be either fuel only cut or fuel and ignition. This is up to you. When you hit a revlimit it will go very lean, since no fuel is being injected.
Posted: Thu Jul 20, 2006 9:44 am
At the rev limit a fuel cut rev limit will stop injecting fuel. There will be a tiny, tiny bit of fuel from wall deposits, but the combustion range of petrol is very narrow - only about 9:1 AF to 30:1 AF, and you're now looking at least 500:1 AF, so there is nowhere near enough fuel to support combustion. The lambda sensor actually senses oxygen, and will see almost atmospheric oxygen, so will read lean. This is normal and not a problem.
If you use an ignition fuel cut only, the unburnt fuel will both wash the oil off the cylinder wall and also burn through the cat or turbo (if you have one). Both these things are very bad. Therefore only use a fuel cut rev limit or a fuel and ignition rev limit - not ignition only.
Posted: Mon Aug 21, 2006 10:29 pm
I understand what you mean by the lambda meter will read lean and will actually read a percentage of oxygen. But is it bad to lets say hold it at the launch control rev limit for about a minute. I think it would be bad, because it is leaning out without fuel. This leaning out would cause cylinder temps to climb, and in turn could cause the pistons to expand and score the walls. Could this happen with a fuel cut rev limit, or is it not that dramatic to cause any damage, thats my question
Re: another question
Posted: Mon Aug 21, 2006 11:45 pm
gSIr wrote: I think it would be bad, because it is leaning out without fuel. This leaning out would cause cylinder temps to climb, and in turn could cause the pistons to expand and score the walls. Could this happen with a fuel cut rev limit, or is it not that dramatic to cause any damage, thats my question
There is no combustion, so there is no heat added. In fact, there should be some cooling due to air being pumped through the cylinder. If you had a lean mixture that still supported combustion, then you would have high cylinder temps. So rev-cut should not cause problems.
However, from a balance and shock point of view it always seems to me that rev-cut is a rather violent situation for an engine to endure for an extended time. Anybody have any comment on this?
Posted: Tue Aug 22, 2006 9:36 am
The loading and unloading of the crank, rods, pistons and wrist pins is really hard on bearings and these parts. Why would you want to hold an engine on a revlimit for a minute?
Posted: Tue Aug 22, 2006 8:45 pm
Well not a minute but for an extended period of time, for launching and things of that sorts. Thanks for the info