ProChemBroTCM

I have a 1988 RX7 convertible 5-speed. The only modifications right now are a cone filter, some weight reduction, rear-shock-tower-bar, and all new Royal Purple fluids. I just installed the 3-in CorkSport catback and am still using the stock cat. The first week after I installed it, it was great. A little bit more power, much louder, badass racecar-like backfire on deceleration, really cool. Now though, there is something strange, and I am not sure if it is caused by the new exhaust piping.
Firstly, the car no longer goes into the 3k-rpm warm-up-cycle when I start it up. I don't start the car with the shifter in gear, so I am not sure why it's not going through the warm-up routine.
The second strange thing occurs when I am driving: when I just barely depress the gas pedal, the car makes this strange, somewhat staccato, exhaust note (kind of like brdrdrdrdrdrdr, I don't know if that helps) as opposed to the normal smooth note (something like brrrrr). The car makes the strange noise when I am just trying to maintain speed and not accelerate. As soon as I dip a little bit further into the throttle, the car jumps and begins to accelerate as normal. The most annoying thing about this is the transition from 1/10 (not necessarily accurate fraction) throttle to anything greater than that is that the car jumps once and is normal otherwise, and it is much harder to modulate in low gears (in first or second, the car will start to lurch on and off this strange note - maybe because each lurch causes my foot to move just slightly and transitions between 1/10 and 1/5 throttle). As long as I am not just barely touching the pedal, the car drives fine with no other problems and still sounds great.
The last issue is that the car no longer backfires on engine decel. When I am winding it out, sure, it backfires when I upshift, but no more on the downshift. Instead of going "burr-POP-rrrr-POP-rr-pop-POP-rrr," it just smoothly drops revs with no backfires. Meanwhile, Australia is down there like "WTF, mate?" Please help!

Red_Rabbit86

hey well i had the same problem with a vw i used to own check out o2 sen. if not maybe check for a exhaust leak. other then that i dont really know so i am like WTF mate?

ps: i say that at work all of the time and people just look at me like i am retarted

Turbo II Rotor

iTrader: (2)

My car does the same thing when you are barely on the throttle. I have the stock exhaust so you really have to listen for it. My guess is that by having the throttle at that position your barely giving the engine enough gas to maintain that rpm and the car is pulling the engine that fast and the engine is only firing every couple of rpms. Does it make somewhat the same kind of sound if you rev it from idle to under 2k before it cuts?

NCross

iTrader: (18)

the bdrdrdrdrdrdrdr sounds like the TPS needs to be readjusted. 3 inch cat back is kinda over kill for an NA engine so that could be causing you to loose low end power. your auxilery ports could be chattering more now with the increased air flow. Im no expert though.

ProChemBroTCM

I have actually noticed (at least I tell myself I have) a slight increase in power all throughout the rev-range. Oddly enough, the car stopped doing that noise thing about 2 or 3 days after I posted this, but I haven't yet checked the O2 sensors. Now, the throttle still has a knife-edge between on and off, especially at low rpms, but it is hardly noticeable in the higher gears. I am actually getting about 1 more mpg now, too. Just yesterday when I filled it up, I calculated 18.2 mpg, and that is with me almost constantly beating the tar out of that car. I just visited the local Pull-a-Part and snagged a nice throttle body which I will be working on to remove the primary double throttle body for better airflow. I can't wait to get my RB streetable header! The ebay deal is definitely going sour, though. The jackass was supposed to ship it to me by June 20; That was a couple of weeks ago. I will give him the rest of the 30 days from that date before I lodge a complaint.

Agent_D

iTrader: (2)

adjust your TPS for the throttle issue, and yes i'd say replace the O2 sensor and get a high flow cat if you are keeping the cat.

i still have yet to get the right adjustment for the TPS in my car, but im not too worried about it since all of my stuff is removed, modded and largely ported TB, removed bac and all that. so far i notice that setting it for around 900ohm at idle has been the best, i think its supposed to be 1k ohm at idle stock.

ProChemBroTCM

Hoo boy, I just can't wait to figure out how to fix the TPS. I really hate working with electronics. Hmm, that reminds me. The car will idle at about 750-850 rpm, and it sounds great, but it will only settle into that range when the car is warmed up and I put the shifter in gear without letting out the clutch. I can put the shifter back into neutral, and let up on the clutch, and it will stay at the proper idle, but otherwise it will idle at a steady 1100-1200 rpms. Oh yeah, the car still doesn't do the 3k rpm warm-up cycle, and I am not sure why. I don't really miss it, though. Any ideas on those last 2 things?

ProChemBroTCM

So, no ideas, eh?