I gutted my cats (sloppy welding it back on, and many leaks, due to running out of gas)and it seems to go through my first gear faster, but above 65-70 it is very slow. It used to pull pretty well all of the way to 90 or so. Would the exhaust leaks cause this? Also, not that I'm dying to have it or anything, but.... I heard it would shoot flames, and i hardly have any popping. I'm thinking its probably lean, or it could be leaky cat or clogged muffler, but I definately need a second opinion.
BTW i have a 91' na auto.
Any help is appreciated.
Ryan

 

well if it ran fine before and now it doesnt with the gutted cats.... i would get the welds right then then see how it runs or y not take the cats off and use a few feet of 2" straight pipe?

 

sounds like the 5th and 6th port isn't oppening.

 

^^ that is your problem your 5th and 6th ports open from the back pressure of your exhaust.... search for the 5th and 6th port they make a kit that opens them when need and doesnt rely on the back exhaust pressure

 

you can also hook them up to run off just the air pump

 

At one point I had the aux ports wired closed, and the exhaust line that supplies the ports with pressure I had capped (I was in the middle of testing something). The cap developed a crack, and from time to time it would vent. So what I had was a pencil-sized exhaust leak that would turn on and off at random, and my aux ports were wired closed.

The interesting thing is, when the exhaust leak would cut in, not only would the engine sound like a tractor as expected, but I would lose a good deal of power. So, fix the exhaust leaks, and you'll probably kill two birds with one stone (aux ports opening and fixing the issue I'm talking about).

 

To rx7 FC TII: Don't answer if you don't know. Wrong information by unknowledgeble over-confident members is a real problem.


To Bob: You have an S5. Your 5/6 port does not open by exhaust backpressure. It opens by way of the ACV. It is more complicated and more sophisticated than the S4 system, but it is totaly unrelated to your exhaust system. I doubt that the issue you are dealing with involves your 5/6 port, unless you have changed something else, knocked something loose etc.

FSM and the Haynes manual have pretty good trouble shooting proceedure that you can use to determine 5/6 port operation if you want to check this out.

Search is a better friend than the misinformation given to you on this thread.

good luck

 

Good catch about the S5, I missed that myself. Still, I have experience with power loss due to exhaust leaks (per my post above), so do fix those.

 

Holy misinformation...

On the S5, the aux ports are opened by the AIR PUMP. Note that this DOES NOT mean the ACV. There is a port solenoid on the rack that opens them up by allowing pressurized air to the actuators...This is all in the FSM...

 

damnit arron, i was enjoying watching people "explain" the n/a aux port system. why ruin our fun? lol

 

In Jack's defense, he probably meant air pump anyway. Good catch Aaron, I missed that one as well! Guess I need more sleep - or coffee. Coffee sounds good.

 

Thanks for the correction, Aaron: I yield to one of the Masters of the Forum.

I made the mistake of answering very hastily and focused on the misinformation, then spread some of my own.

My humble apologies all around.

BTW, I do know the ACV function from the the vdi solenoid, the port solenoid functions etc.

I even know my ACV from a hole in the ground, but it doesn't seem like it today.

I think I will take a drive.

 

still running stock mufflers? and btw the flames (for me atleast) only occur between 3k shifts and high rev decelleration

 

wow.....i guess i was fed miss info also then...i guess thats why i dont own an n/a also...

 

less backpressure = less torque and that is something you really dont want to lose with an auto transmission.

 

lol thats y i didnt say anything about back presure bcs its a s5 on the other hand.... i know that leaks in try duels and in headers can act like a cam with uneven lobes and will cause a engine a lil rough

 

yeah the fifth and sixth ports are opening fine, i really only notice how slow the upper rpms are at high speed, i'll try seeing if sealing those exhaust leaks will do the trick.

 

hows it running with the leaks fixed?