Okay, here goes my sad, sad story... I just bought an 88 RX7 TurboII. She had sat up for a few months before I bought her. Everything ran perfect on the way to my house, and the same on the way to the DMV. I filled up the tank with some Unleaded Plus, and she ran oh so good for half the day. Then, things took a turn for the worse. Backfire... like shooting flames from the exhaust tips backfire, which isn't so bad. The fool at ABC Auto sold me 4 leading spark plugs instead of 2 trailing & 2 leading, so I changed out the spark plugs. Still backfiring, but only when its in lower gear. Okay, so my buddy comes over, and he says the top plugs aren't getting any spark, so we pull the coil pack, and replace it. Now my baby won't even crank. Any advice on the original backfire issue & now how we got to this point??? Any advice would be greatly appreciated; I need to drive my baby!!

 

Check for spark again after you replaced the trailing pak?

 

make sure the leading plug wires are going to the right spots on the housing. L1 to lower housing 1 and L2 to lower housing 2.

You don't need trailing spark to start and run the car. Sounds like something was removed and not put back in the right places to me.

 

Thanks... I'll have to double check the placement on the leading wires, but everything was fine before removing the trailing pack and replacing it. So, I'll just have to double check everything. Any ideas on the original flame-from-the-exhaust problem?

 

I have experienced this when a spark problem occurs.. Check your spark.

 

If your trailings weren't firing originally, then there would have been some extra unburnt fuel in the exhaust. That is probably the cause of your backfires. Really, any rotary without emissions will backfire with flames, especially if you don't have anything to lean out the fuel mixture.

 

Did it backfire when you were on the gas, or off of it? Just about any rotary without emissions and catless exhaust will shoot fireballs out the back on decel.

 

Better to bump an old thread than make a new one. Someone gutted the cat from my TII before I bought it. If you want it, you can have it, since I'm picking up another one today.

Anyway, my TII backfires under decel as well (catless stock exhaust). It also smells really rich. Once I put a working cat on, it'll stop backfiring, right? Will that also make the exhaust smell less rich? I was wondering if I should buy a s-afc to adjust the a/f ratio, seeing as how I don't really know how to measure and/or adjust the ratio without one.

As a side note, the TII exhausts on mine were crushed and I put on NA mufflers as a replacement. I've never seen it done and it bolted right up. Any thoughts as to what may happen?

 

Yeah, the backfires will go away once you put a cat on it. And the stock NA mufflers are more restrictive than the stock turbo ones, so you're losing a bit of power. Get some Racing Beat duals, they have a nice deep sound and high flow.
http://www.racingbeat.com/FRmazda2.htm
$484 for the pair, $165 for a y-pipe

 

Yea but I paid next to nothing for the NAs. I wonder how they affect backpressure...

So yay! The backfiring will go away with a good cat. What about the rich smell? Besides the oh-so inaccurate sniffer test, how do I know if I'm really running too rich or not. I know the 7 runs rich normally, but I mean more so than usual.

 

less fuel vapor = less (or no) backfires = less fuel smell. You can run an air/fuel guage or an exhaust gas sniffer to monitor the ratio. You can adjust the mixture to lean or rich underhood (in the manual), but if it's not melting your cat, it's probably fine.