yo wassup guys i have a 89HF REX with a 90si motor and errytime i drive it in between shifting greats it backfires...what could be the problem?

 

Exhaust leak, most likely. When you have an exhaust leak, and you are changing gears and exhaust pressure is decreasing your exhaust system usually sucks air in which touches your hot valves causing the *POP* sound you are hearing. Take your car to an exhaust specialist and have them look it over for leaks. Or look for them yourself. Most leaks can be heard.

 

yea i found an exhaust leak where the weld from the piping to the muffler is at thanks dude

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by manyakiexpi &raquo;</TD></TR><TR><TD CLASS="quote">yea i found an exhaust leak where the weld from the piping to the muffler is at thanks dude</TD></TR></TABLE>

Would that really cause back firing?

 

my rex backfires occasionally when i shift of going downhill and let it compression brake, it used to be really noticeable and pretty loud when i had a leaky shitty exhaust, put on a new system and i can barely even hear it when ever it happens now.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman98 &raquo;</TD></TR><TR><TD CLASS="quote">Would that really cause back firing?</TD></TR></TABLE>


im assuming it would? well thats what B16aSir2 said so ima go with what he said and try pathing up that leak with some jb weld n see if that does the trick. HOPEFULLY it works

 

dizzy??

 

the majority of the time its only because you have an aftermarket exhaust ( if your not running a stock one ). and with an aftermarket exhaust the piping is bigger. so you are able to hear some backfire vs not being able to hear it as much while running the stock exhaust.

 

But guys, let's look at the actual cause of the POP sound. It is when the valves(extremely hot) meet cold air(or normal temperature air) and creates an explosion type sound.

You can demonstrate this affect on your stove. Grab a coke can, fill it 1/3 of the way with water. Now put it in a pan on the stove and let the water get to boiling temp. Then get a bowl of ice water big enough to fit the can into and put it next to the stove. Grab the coke can(once it has heated up) and quickly place it upside down into the ice water. WAALAHH. The coke can is crushed. Imagine what happens to your valves

I would redline my 2nd gear or third gear at 8400 rpms before approaching a traffic light with my little exhaust leak I had at the 4piece to 2piece part of the header. When I took my foot of the gas and let the rpms wind down it made such a ******* deafening pop that you would think I dropped a valve or something. I thought I was so cool lol. I thought it was a performance thing or something. What a dumbass I was lol.

 

true true...