scott_06

Okay, so i bought a 85 gsl-se. it was missing alot a stuff motor wise, just small things, had bad idle issues and didnt want to stay running. over this past month iv replace or better yet put stuff back in. I got it running great now. starts everytime, idles great, dosnt die. but if im driving and its at 2,000 rpm in any gear and i let off the gas and leave it in gear it back fires at least two times and its lound! sound like some one just threw a rock on my back end and a puff of black smoke rolls out with the pop! now i understand theses cars back fire but this seems kind of more excissive than a normal back fire.

Now the car has the oem header with no cat and open exhaust. a list of what iv put back on the car:

A/C belt
Air Pump & belt
Water Pump
Plugs/wires
new gas tank
fuel pump
sending unit
rewired wipers
and i adjust the idle screw and the ?fast idle screw? (to fix the idel)

Not sure if some of that matters but thats everything ive tamperd with.

orion84gsl

iTrader: (5)

Idle screw and fast idle screw???? Do you have a carb on your car? If so it's not a GSL-SE, it's a GSL. Significant diffference being the Carbed 12A(GSL) and EFI 13B(SE). Also there is no fast idle screw, there's a idle speed screw and idle mixture screw. Check out your fuel filter, this gets missed alot and could make a significant improvement in the way your engine runs. Also not having a cat will make the car backfire more, although I cannot explain why it seems to do it more often on your particular car. I'm running not cats and it only really backfires if I take it to redline then let right off the throttle.

djessence

You may have an exhaust leak that is allowing fresh(combustible) air into your exhaust. Check for that, should be able to hear it when car is idling if you listen

scott_06

it dose have a 13 b in it. theres a idle screw on top of the TB and to the left theres anthere screw. i thought it would be the fast idel screw. well thats what the hanes said, probly wrong tho. the fuel filter was one of the next thing i wanted to replaced.

scott_06

it dose have an exhaust leak, mostly in radom places in the cat back. fixed most of them for temp use for right now untill i get the new exhaust system in.

littleredrotary

when mine ran rich it would do that, and also make lots of fire. could be the exhaust leak tho.

lets spin

i this post is old but i'm having the same issue. Differeance is i have the RB full system with no air pump. There are no exhaust leaks and based on a smog check, i'm dumping HC's but my fuel injectors are not leaking. anyone wanna take a crack at this? its been driving me mad and my boss knows very little about RX7's.

thunkrd

iTrader: (1)

the RB system doesn't have any cats... which would make your HC to be pretty high

DivinDriver

iTrader: (15)

"Afterburn on decel" is something that stock engines had several systems to control; air pump, air control valve, anti-afterburn valve, decel valve, richer circuit, dashpot... butterfly valve on later engines...

When you strip all that "rat's nest" stuff off & switch to headers & a stripped carb, you find out why all that stuff was on there. Mix becomes critical. An afterburn is hte result of dumping an unburned overrich air-fuel charge into the hot exhaust system, and then following it with a still-burning charge that ignited properly. Boom!

The dashpot (that most people remove when modding), which limits the closing speed of the throttle, is a major preventer of afterburn.

lets spin

i know the lack of the cats is part of the cause of the high HC's. The good part is this is a 13b so i don't have some of the dashpots and richer circuits. i'm more thinging about the antiburn valve. is there a tuning way around not having that. the rb exhaust system cam with the block off plate for the side of the intake manifold and a cap for the air box where the air pump use to plug into.

lets spin

i'm alos having a tough time figureing out what a anti burn valve really does and how it works. i just feel like i'm still pumping lots of fuel on decel and its exploding in the exhuast.

nobodymv

iTrader: (3)

The Air Control Valve (ACV), in a nutshell, keeps the catalytic converter operating efficiently. The goal is to maintain a safe and stable converter temperature, and to continue burning unburnt hydrocarbons by introducing oxygen into the exhaust stream. The ACV does this by diverting air from the air pump to either the main (third) catalytic converter ("split air"), exhaust port ("port air"), or to the atmosphere ("air relief"). Built into the ACV is the Anti Afterburn Valve (AAV), which supplies fresh air into the rear intake port during deceleration to prevent backfiring.

This valve is the large golden valve on top of the ACV assembly.