I just went in for an e-test, failed HC & NO. Both were over by almost double. Everything else passed.

I'm running a GSR B18C1 motor w/ 4-1 header & JDM type R cat (used).

Any ideas what the problem is? Is it just a faulty cat that needs to be replaced?

NEED SOME GENIUS HELP HERE! THX!!

 

the cat could be too far back cause of the header, may not be lighting. if you can get someone to do a 2 speed idle you could retard the timing and decrease fuel pressure if you have a regulator on the fuel line

 

Could I simply change to a new high flow cat (ie. Magnaflow) to pass?

btw, I failed in the ASM 2525 test. idle is ok.

 

the problem is where the cat is located, normally with the stock header its right at the end of the header close to the motor, now that youve got a race header the cat has been pushed back so its not heating up as hot as it should cause its further away from the engine, to start i would get a heat gun and throw the car in the air and make sure the cat is lighting, if it isnt you can take a plug wire off and ground it to the body or block (its very important that you ground it) that way youre dumping fuel into the cat and itll eventually light then see if it changes it within 4 to 5 min. you can pass with a little tinkering here and there ive done it a few times myself. the best way like i said is to decrease fuel pressure cause all your worrying about is hc and no

 

Retard the timing, should be good. And the whole cat location...its almost the same, no difference should be seen.

 

By how much do you recommend to retard by?

 

turn the distributor back so the timing is 5 degrees BTDC (before top dead center) retarded so 9 to 10 degrees would be the reading on the timing light, spec is about 14-18. youll probably need a timing light im not sure what way is adv and which is retard, mark the dizzy before you move it. itll probably run like a bag but after the test turn it back and itll be good to go

 

Retard it sto the end. Car will be gutless but will run.

 

Can retarding timing lower emission by half? I was over by almost double.

 

Did you try cleaning the throttle plate?

 

retarding the time will not make a difference that much if its double. You most likely need a tune up (plugs and wire) maybe a 02 sensor,and it could be the cat.The tune up will effect HC mostly and the cat and 02 sensor will most effect the NO.

You best bet is just let the shop get it to pass, it never really cost more then $100 most of the time.

Plus when they do the test let them know you have a engine swap, because they will put it in as a hotrod and it raises all the limits.

 

hot rod doesn't apply as its the same displacement as factory displacement