I have seen others telling people its normal to have this machine gun sound coming out the exhaust..nothing could be further from the truth...

My RX7 was doing this same symptom, I tested my TPS it was out of range I put it back into range with voltmeter, tried it agin no dice, checked TPS agin kept going out of range, replced the TPS and all the poping, machine gun sounds went away, and the car running perfect again..


I have seen in the past others saying this is normal..that is wrong...backfiring is not the same as this...I still have the common backfiring from a free flowing exhaust/header..but the super loud machine gun sounds are gone, and was casued 100% by the TPS being bad...

later

 

No it's not normal, its usually a bad or misadjusted TPS like you found out. Once you have the 13B running good it really shouldn't backfire much at all, unless you are really doing a spirited run and it's decelerating......

 

what rpm range was it doing this?

 

Most times it would start around 2500 to about 3000, I don't know, if happens in the higher ranges, because the sounds was terrible, and sounded like the engine was coming apart.

I would guess, if you have the same situation/sound it could occur @ any range, depending on where the TPS is out of range, either the high side or low side.

I would assume, if I had pushed the engine farther into the RPM range, it would have blown itself up.


Put it this way, I have totally built at least 30 cars, and never ever heard this noise, except on some Youtube videos..It was not a good thing in anyway, shape or form!

 

i had the same problem it turn out to be the feul pump.

 

um

Does it sound like pop corn and gets louder and louder per rpm?

Your timing is probably too advanced and its pinging, I had that & the temps got really high one day causing that....