Removing pre-cats -- worried about 5th/6th ports
 

My FC is failing the emissions HC test. The main cat is most likely done, and I've read that the pre-cats disintegrate into the main cat over time. So I'm planning to install a high-flow cat and replace the pre-cats with straight pipe. I'm hoping this will pass me on emissions, and if it doesn't, I'll kick the Air Team guy in his nuts and go apply for an emissions waiver or something.

(Quick Air Team story: Dude pulls my baby into the test station, already burning clutch. I almost decide to look away for this one when I realize the front wheels are on the dyno, and he's about to launch my car into that huge fan. I jump out of the "observation lounge" and start screaming at him. He looked at me like I'd caught him smoking crack, and said with a heavy name-your-minority accent, "oh no, I think this Honda...")

Here's my question: With no pre-cats, a high-flow cat, and stock mufflers, will my car have enough backpressure to open the 5th and 6th ports properly?

1987 N/A.

Not very effectively, no...that's the simple answer...I've been tweaking mine to perfection for about 9 months now, since I put the open exhaust on...the short of it- 1)route your existing port air pressure feed to a fitting that will fit in a hole you've drilled in your air pump-to-ACV hose... 2) install a "T" in this line, putting the air feed line on the straight ends, then drill a (approx.) 1/8" hole in the "base" of the T for exhaust...start with a smaller hole, and visually verify port opening with tach readings while goosing it from the throttle body (if ya need a helper, my 7 year-old daughter can give you a "thumbs-up" from the driver's seat when the tach hits 3500, lol...)...If you just feed a straight line, your ports will open at around 1500 RPM, hence the need for a "calibrated" hole in the T...

Shit...Wayne...Since my ports SUCK...I have no Air Pump, I have no secondary air system...can I just tie the ports and throw in a straight pipe? Or is there a better way with my setup? I need to know by tomorrow morning...well...by 8pm...it is 7pm now...

Damn, didn't know you had no pump...Heck, it isn't like it sucks down 10 horsepower, I just leave mine on (I also have the ACV rigged to continuously dump port & split air, because an open exhaust stinks, and it 'aint like I'm trying to pollute our over-polluted world even more...)

You're going to have to use more exotic methods for your ports, I know there are several threads on rigging these things up, look 'em up...I don't like the idea of just wiring them open, or removing them, but that's just me...

Shit. That sucks... Yeah, it was already off when I got the car. Not to mention, the Port Air Solenoid valve was causeing my EGI Unit to fry, so I disconnected it rather than running all new wires for it. My car was a problem car...I suppose I will try to tie them open and if that doesn't work then I will be back on here and figure it out...Dammit...I got a long day ahead of me. Would it be a better idea to tie the little valve things open or tie the actuator rods down?!

Easiest short-term thing would be to tie-wrap the actuator rods down, but take it for a drive & see if you can handle the loss of low-end power...

It hasn't displayed that low end power loss...They have been tied for two days...

Okay. But that's a bit more involved than I'm prepared to get (unless I have no other choice). Would I be all right if I left the pre-cats in there, or is the high-flow cat already going to hurt backpressure too much?

BTW, what happens if the 5th and 6th ports don't open?

You could gut the front 2 stock cats, and keep the main one, you'll feel a nice power increase with just that...In fact, after I got the Bonez, there was no discernable difference between it & the setup I just described.

My ports didn't want to work right after I put in the Bonez- I know there's the split air connection on there and all, but it just wasn't doing it's thing (especially after I put the RB turbo mufflers on later on)

If your 5/6 ports don't open, you'll feel kinda sluggish up in the RPM range, like you know there should be more "oomph", but it just isn't there...

hey wayne, do you have a pic of any sort for what this looks like? the 5-6 port rods linkages or what ever makes them work. I happen to have been reading this thread and relized that mine may not be opening. SLUG.. SLOWWW SLUG up in the RPMs.

sorry didnt meen to bump in but this is a good thread to me and my knowledge in the workings of this engine :D

thanks guys

PS I have the 1 main cat and a straight pipe from the turbo the 5-6 ports run off the exhaust ohhh my

rxcollector, do you still have your air pump?

Sorry, no pics... :(

yup I still have it :D

PS the car idles now :D thanks

oh wait does this apply to my TII??? or only NA?

So you're saying that if I put on a new cat to pass emissions, I'm going to lose high-end power?

Emissions is a big deal in IL (at least near Chicago). And I can't get an emissions waiver until I produce $450 worth of emissions-related repair receipts.

The car is running well and I'm not really looking to add power (not that I'd be opposed to it). I certainly don't want to cripple the car by eliminating too much backpressure, but I need to pass emissions now -- the car's registration has been suspended for failing. The only thing I know for sure is that a replacement main cat from Mazda is out-of-the-question expensive.

There have been a couple of guys on this forum that have passed with the Bonez hi-flow on there, so that shouldn't be a problem...In fact, I'm sure it will perform better than that 16+ year old one you've got now...As long as the ACV is working as advertised, you shouldn't have a problem...Do a good tune-up, stuff like that...