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Shotgun backfires

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Old Feb 26, 2003 | 05:02 PM
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ForsakenRX7's Avatar
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Shotgun backfires

I just put on a 1st gen dsm BOV on my new 90 TII. I also removed the airpump. The previous owner already removed the presilencer and main cat and the car is running a lil rich. I take it I'm shooting flames now. However, the problem is if I go past 4k maybe 4.5k rpm and let the rpm drop I get a hellacious shotgun backfire. I'm talkin ****** loud too, scares the **** out of me. Is there anything I can do to tone it down a lil bit? The car is still runnin the stock mufflers I believe. well, they look stock.
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Old Feb 26, 2003 | 05:08 PM
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haha N/a's are supposed to be louder than TII's and my back fires are not lound at all. You must have sensetive ears or something. To sone it down I guess the only thing you could do is get new cats and stock mufflers. Anything else will be loud since anything else if for performance. I like my exhaust it has Racing Beat cans and at idle or cruise they are less noisier than my old 16yr old stockers.
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Old Feb 26, 2003 | 05:08 PM
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From: Mars
glass packs, presilencers, cats. Pick which you want to install.
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Old Feb 26, 2003 | 05:13 PM
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From: Mars
glass packs, presilencers, cats. Pick which you want to install.
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Old Feb 26, 2003 | 05:16 PM
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when mine backfires (when its screwed up)

It sounds like an artillary cannon
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Old Feb 26, 2003 | 05:56 PM
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I always used to get a lil pop after leting off higher than 43oorpms but now I have to go to the redline to hear a pop. I guess it still pops even when I don't go to the red line but the exhaust gets lound after 5k so it is hard to tell. I got two pops today when I did my daily red line. One after shifting to second and another going into third. I let off after that cuz taking it to the redline in third gets scary now. not to mention that I am low on gas.
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Old Feb 26, 2003 | 06:43 PM
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From: Augusta, GA
Adjust your TPS my brotha. Run a search and check how, also, look for vacume leaks. You shouldnt hear backfiring that loud. I got pulled over in my neighborhood because my car would shake houses from backfiring. Turns out it was just a vac leak and my TPS was way the **** off. Shes silent, and alot quicker now.
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Old Feb 26, 2003 | 07:00 PM
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From: Olympia, WA
Originally posted by 1987RX7guy
haha N/a's are supposed to be louder than TII's and my back fires are not lound at all. You must have sensetive ears or something. To sone it down I guess the only thing you could do is get new cats and stock mufflers. Anything else will be loud since anything else if for performance. I like my exhaust it has Racing Beat cans and at idle or cruise they are less noisier than my old 16yr old stockers.

Last edited by marcus219; Feb 26, 2003 at 07:07 PM.
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Old Feb 26, 2003 | 07:01 PM
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From: Olympia, WA
Originally posted by 1987RX7guy
haha N/a's are supposed to be louder than TII's and my back fires are not lound at all. You must have sensetive ears or something. To sone it down I guess the only thing you could do is get new cats and stock mufflers. Anything else will be loud since anything else if for performance. I like my exhaust it has Racing Beat cans and at idle or cruise they are less noisier than my old 16yr old stockers.
TII's quiter in exhaust note sense...hes turbo..plus hes running rich as **** it sounds...big flames and louder back fires.....

it'll keep ******* from tailgating you...burn their bumper!!! hahaha
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Old Feb 26, 2003 | 07:03 PM
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From: Olympia, WA
every other damn time i post..it gives you the this page cannt be displayed crap..so i try it again...double post..err
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Old Feb 26, 2003 | 07:34 PM
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hmmm... ok,
Has the new BOV been ducted back into the intake? (after the AFM)

Problem is that when you let off, the BOV lets out air from your intake tract. Air that the computer still thinks is in there... so it dumps the appropriate amount of fuel in too, but since the air isn't there anymore (it was just dumped by the BOV) you run hella rich... leading to a backfire....
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Old Feb 26, 2003 | 07:37 PM
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As far as fixing it goes, hmm... well.... uhmm...ask a turbo owner...
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Old Feb 26, 2003 | 07:42 PM
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From: Mars
Put the AFM after the intercooler, so its after the bov
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Old Feb 26, 2003 | 07:47 PM
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brap brap
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From: Migrated back to Gulf Breeze, FL
Hey Roger,

i'm happy you finally got a RX-7 back! So I'm guessing you never got your POS DSM working so you finally gave up and bought another RX7? Way to go Now..where are the pics?
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Old Feb 26, 2003 | 09:35 PM
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Hey christi! I did and I didnt give up on the DSM. I still have it. I think I'll turn it into a drag car. ANyways, no my ears arent sensitive, this thing is WAY loud when it backfire. Lights up the street at night behind me. I had a friend follow me earlier to see if it was blowing flames, I took it up to 4500 and let off. I started drifting back down in speed and he came close up on me then BOOOMMMM!!! He started dropping way back and flashing his brights. tooo funny. He tried to pass me and I let off and backfired a flame right at his door. he didnt pass me. he fell way back that time. We got back to my house and he was like" Man that **** will scare the **** out of someone. I watch the front of my car light up and fire and ****. That things nuts."
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Old Feb 27, 2003 | 12:21 AM
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Originally posted by dr0x
Put the AFM after the intercooler, so its after the bov
Nope... then you are measuring the flow of pressurized air, rather than air at the pressure sensed by the air pressure sensor... although maybe if you put the pressure sensor at the same place... hmm... but it may be out of the range of acceptable values...
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Old Feb 27, 2003 | 12:22 AM
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I think too much...


Oh, and BTW, glasspacks will melt with the heat from a rotary
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Old Feb 28, 2003 | 12:02 AM
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Ok I went to adjust the TPS today and was going to set the screw an the BAC afterwards. But I was like, well maybe the oxygen sensor might be bad. Thats why I'm partially running too rich. Yea well, its bad alright, in fact it was so bad that the previous previous owner took it off and welded the hole shut. Some SOB removed the damn O2 sensor. So now what do I do? Cause its gonna continue to run rich I presume without one. Any suggestions?
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Old Feb 28, 2003 | 12:57 AM
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dude, did you read what I typed?!? ....The O2 sensor will make you run rich but only when you are cruising, it has nothing to do with tuning during acceleration or deceleration... the problem is you are loosing air from your intake tract because of that blow off valve............
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Old Feb 28, 2003 | 01:30 AM
  #20  
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From: Gainesville, Fl
yea I read what you said but It was running way too rich when I bought the car. My wife said I was making her eyes burn when she was behind me on the way back. I just put the blow valve on it maybe a day or two before I posted this problem. Come to think of it...thats when it started to really backfire like a shotgun. I mean it still backfired a lil before but not like it does now. hmmm, well that partially explains it. However, I'm still running entirely too rich all around. What should I do about the missing 02 sensor?
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