acrouse

I have searched and didn't really find a good answer to my question, so I would appreciate any help. The past few weeks I have noticed a popping sound coming from my '87 NA when I shift at higher rpm's (>4000). My first two thoughts as to the cause were either a slipping/loose clutch plate or backfire. The clutch is only 25,000 miles old (there are 174,000 on the car), so it should be okay. But if the car is backfiring, I would expect a loud pop; this is only a relatively small pop. If the radio is on, you won't hear it. The car is stock, no modifications. If anyone has suggestions or ideas, I'd appreciate the help. Thanks!!

yearrgh

it isn't a metallic ping, is it?

blu_gxl

no it's the small back fire you get after you put on an aftermarket exhaust or if you get rid of your cats if that's the case you should be fine that's somewhat normal

Nick86

iTrader: (1)

Mine does it on decelleration, and it only started when my TPS went bad.

Check and adjust the TPS, and it will probably go away.

wozzoom

The original post states the car is stock, so the reason is not because of an aftermarket exhaust. It is also not the TPS because the post states that it happens while the car is accelerating above 4000 RPM. The S4 TPS isn't even being monitored at this time.

THE CORRECT ANSWER IS?
EGR Valve.
I'd put money on it. The rubber diaphram of the EGR valve deteriorates causing a vacuum leak. The end result is the EGR valve gets stuck in the open position. Remove the EGR valve and block it off. You don't need it. The bad news is that you have to remove the intake to get at it.

Good luck.

acrouse

Thanks for the input. I'll check it this weekend (the weather is nasty out right now). When I left work this afternoon, the car smoked like crazy for the first two minutes or so I was driving (it's never smoked before). I am assuming that if the car is backfiring, this may also be a result of too much fuel mixing in the engine?? If so, what would cause it to quit smoking? Once the engine warmed up? Thanks guys!

rx-7s rock

my 86' N/A base backfires when I accelerate hard thru first and on the shift to second it gives a nice loud pop. Then when I shift to third it is a little softer. Also backfires when engine braking. My exhaust leak is not really the main cause, the car did it when the exhaust was new. So I guess I'd have to play with that valve that is most likely busted, but would that make the backfires go away? Cuz I like the backfires. They rule.

Amur_

They aren't BACKFIRES. Backfiring is a piston thing. Call it Afterburn. Do a search for more 411...

rx-7fc

today i got a Bearing or gear noise but only in 1st,2nd,3rd and,5th but not 4th and it does it more when you let go of the gas but it goes away a little when you are driving

superpimp35

welcome to the world of Backpressure/afterburn

KiyoKix

Anyone have a write up on the removing the egr valve?

Amur_

https://www.rx7club.com/forum/showth...ght=remove+EGR