RENIX:Pre-Heat air/fuel mixture & e

Greets: What are the downsides of removing the OEM pre-heat duct, and blocking off it's port to the OEM air filter box?
Thanks ahead.:eyes:

Mostly cold start emissions. Possibly a bit of driveability as well. Very little effect generally, considering how many of us have had those things rot and fall off over the years. Beware if you live in a state where emissions equipment is visually inspected. I don't think you will gain much, if anything, by taking it off, and less yet by blocking off the port if you do. It should switch out when it's warmed up anyway, I think.

Thanks for the warning re: living in an inspection State. I'm near the end of the road on the top of the North American Continent, and there is no vehicle emissions requirements here, other than noise pollution, lol, meaning--sans muffler.

Cold start emissions would affect sensor readings as per ECU commands as per lean/rich fuel and air, spark timing, right? I do not entirely grok the 'gain much', or 'less' points raised. I think you are correct as per the air box butterfly to blend, or not to blend is probably 'switched out' when warmed up. In the winter, on my model 17, 258, carbed, I'd tie down the flapper to maintain as much warm air I could get down the carb to prevent it from freezing up solid, i.e., caked internally, and externally with frost, and bits of ice.(only minus four right now). XJ is new to me, and am concerned that there will be raw fuel leak down into crankcase oil, or some O2, or some _____ other slow death malfunctions, that will stress out the engine, and implied, and stated components, lol, as determined by some French computer during the first few miles of driving from dead cold.

My intention is to dis the air/filter box, replace with a home built battery tray, reroute the air intake hose/filter through the cowling, but do not see an easy way to maintain an effective pre-heat system in that mod., in order to keep the OEM efficiency'balance' as determined by the springs, vacuum, and solid state engineers.

As for gaining and losing, as I understand it, you may gain some driveability when the engine is cold, but hot intake air gives less density, so you may gain a little horsepower with colder air. What effect you see may depend on how the engine management system reads and compensates for these things. And of course you don't need to worry about carburetor icing any more. You could probably find out pretty easily if you take the tube off and cover the hole with foil or something. Drive a while and see if you can detect a difference. I don't think the heating is very great, and I suspect that the difference is going to be detectable mostly by instruments.

It will take longer for the engine to warm up and shift to efficient closed loop, and cost you MPGs big time at warm up, other than that it will have more power during initial warm up.

Mine has been gone for at least 7 years on my 87. But it never gets under about 25 - 30 F here.

Glad you guys volunteer to help us all out.., thanks.