Californa Smog Dilema
02-22-06, 10:26 PM
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Californa Smog Dilema
I was given a nice 79 RX7 5 speed because it had failed smog. HC's too high. As a last attempt the owner retrofitted a cat converter to it, still failed. I've verified timing is at spec, both leading and trailing. float levels in the middle, rats nest operation to spec. Smog pump working. Friend that operates a test only station says the smog pump is not feeding the cat and because of this the cats not getting to temperature. I agree with this but since it originally did not need a cat. what am I overlooking? Will fresh plugs make a big difference? When this car failed it was not a gross pollutor just about twice the HC limit. It runs great, revs to 7 grand quickly, starts good cold and warm . choke works great. Any advice? I have both the Haynes and Clinton books and have built street rods swapped engines and worked on piston cars for 35 yrs.
friend
friend
02-23-06, 01:06 AM
#2
FB+FC=F-ME
Simply putting a cat on a thermal reactor tuned engine will not work.
The 79-80 1st gens used the thermal reactor effectively because they were tuned for it.The reactor's needs a fair amount of fuel fed into them to maintain temperature and work.Since there are no catylist materials inside the TR to initiate reduction,the TR relies solely on heat to break down pollution.The 79-80's fuel system is richer and the trailing spark system will shut off sometimes,to insure that plenty of fuel is allowed into the TR, to keep it hot.
At the same time,the air injection system is providing oxygen to keep the reduction happening,but also,some of the air is diverted around the TR's outer jacket to prevent overheating and meltdown of the TR internally.The timing of the diverson,and amount of air which is diverted to those places,is different than on the catylist equipped engines.
In order to make the engine pass CA smog properly,youll need to either revert back to a full 79 or 80 TR system....... or do a complete 81-85 emmisions control swap and have the refferee reclassify your car to the smog standards of the year of engine that you obtain the smog gear from.This is equivelant to doing a later model engine swap,and is basically the same as what I went through with my 87' and then 90' TII swap.
81-85 smog gear consists of year specific.....
Leaner burning carburetor
Electronic ignition
Multiple catylists
Air control valve and plumbing
Rats nest and solenoid rack
ECU to control all of the above
Its CA,.....theres very little chance youll be able to avoid this unless you live in a rural area or take a more quasi-legal approach to it,like high levels of alcohol in the fuel tank,a rural P.O. box adress,bribery,ect......
The 79-80 1st gens used the thermal reactor effectively because they were tuned for it.The reactor's needs a fair amount of fuel fed into them to maintain temperature and work.Since there are no catylist materials inside the TR to initiate reduction,the TR relies solely on heat to break down pollution.The 79-80's fuel system is richer and the trailing spark system will shut off sometimes,to insure that plenty of fuel is allowed into the TR, to keep it hot.
At the same time,the air injection system is providing oxygen to keep the reduction happening,but also,some of the air is diverted around the TR's outer jacket to prevent overheating and meltdown of the TR internally.The timing of the diverson,and amount of air which is diverted to those places,is different than on the catylist equipped engines.
In order to make the engine pass CA smog properly,youll need to either revert back to a full 79 or 80 TR system....... or do a complete 81-85 emmisions control swap and have the refferee reclassify your car to the smog standards of the year of engine that you obtain the smog gear from.This is equivelant to doing a later model engine swap,and is basically the same as what I went through with my 87' and then 90' TII swap.
81-85 smog gear consists of year specific.....
Leaner burning carburetor
Electronic ignition
Multiple catylists
Air control valve and plumbing
Rats nest and solenoid rack
ECU to control all of the above
Its CA,.....theres very little chance youll be able to avoid this unless you live in a rural area or take a more quasi-legal approach to it,like high levels of alcohol in the fuel tank,a rural P.O. box adress,bribery,ect......
Last edited by steve84GS TII; 02-23-06 at 01:09 AM.
02-23-06, 09:52 PM
#3
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Replaced all spark plugs, replaced air filter, replaced fuel filter and added 1 gal. of denatured acohol with 8 gal gas. Car smoked at idle for about 15 min. then cleared up. Took it to a test only station and it passed! max HC is 288 allowed, mine was 286! The car had AUTOLITE single electrode spark plugs in it! which were replaced with NIPONDENSO
brand. Thanks for all the input and quick response. now its registered and licensed.
brand. Thanks for all the input and quick response. now its registered and licensed.
02-23-06, 10:21 PM
#5
FB+FC=F-ME
Wow,nice job....it dont get much closer than that!
The alcohol is a proven "trick",but the tuneup probably helped a lot,especially the ignition.
Denso plugs are just as good as NGK so long as you run the right ones.I actually got more life out of Densos than the stock NGK's.
The alcohol is a proven "trick",but the tuneup probably helped a lot,especially the ignition.
Denso plugs are just as good as NGK so long as you run the right ones.I actually got more life out of Densos than the stock NGK's.
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