I did a search for pops, popping + decel and read the all threads, so I know this has been covered.
My case is a little different. The popping started after I fixed a large vacuum leak (UIM to brake booster hose).
Now for the rest of the story-Last week when it was really cold here in Michigan 10*F, I started the car and the used a little accel pedal to allow it to warm up (no BAC or ACV). It did not want to idle so I thought maybe it was the temps. I ran it for a couple minutes and still could not get it to idle, so I shut it down. Thought it may have been a clogged injector, because it seemed to run fine when I revved it above 3800. I removed the UIM and found the brake booster hose broke off at the fitting. I replaced the hose. Started the car and everything was back to normal, except for the popping noise on decel.

My set up
88 T2
6 port long block, mild street port
S5 Hybrid turbo
Stock DP, Gutted cat
Unknown pre-silencer
CS 3" cat back

TPS set to .94 volts
Fuel pressure 45PSI with vacuum hose removed
15in vacuum @900 rpm idle

My question, If the noise is normal(according to the threads I read), why didn't it make this noise before. Why would the popping start after the vacuum leak repair and not before?

 

backfires?

 

I guess you could call it a backfire, most backfires are pretty loud though. The noise I am talking about isn't very loud.

 

Sounds like a backfire to me. Do you have cats on your car? I do and I get alot pf muffled backfires.

http://uk.youtube.com/watch?v=9AbgUfbyHe4

 

The sound in your video is what I would call a "burble". Mine sounds more like a child's cap gun.

 

backfire.

 

Found the problem today.
Removed UIM to replace the clutch slave and found one of the tps wires pulled out of the connector.

Thanks for the help.

 

RX7-Wankel-13b related flameage.

nuff' said.

-Richard-