will the removal of the smog pump hose that runs from the H pipe to the headers lead to back fireing ? We took that tube out b/c it was always in the way when working around the tranny, now since the addition of the Magnaflow cat back it seems to want to back fire every so often, sometimes at crusing speeds at about 35 MPH or so, does not always do this but will that removal of the tube have any relation to air flow and causing the exhaust to back fire? The tube was crimped off on the H pipe end. It did not back fire last yr ( well did but it was due to running to rich) Im thinking that b/c of that removal of the tube and b/c of the much more free flowing exhuast on the Magnaflows VS the Suckmaster that it may be causing this.....any ideas/ info ??
Smog Pump Removal and Back Fireing ?
- Thread starter Venom351R
- Start date
94gts
Member
no it shouldnt. i removed mine and have an idler puley in its place. the line is gone too and the hpipe is welded closed where the tube goes. thermactor passages blocked too. also vacuum lines plugged. no problems at all 
Interesting, if in fact this has nothing to do w/ it then anyone have any ideas on why it could be back fireing? Im about 99.9 % sure its not due to it running rich, its got #30lb's injectors and the FP is set at about 36. When it did back fire last summer due to being to rich it would do it when you were WOT and then backed off the throttle and it would then back fire, this seems to do it just while crusing, sometimes it will sometimes it wont.
94gts
Member
94-302-vert
Active Member
I would say that the cats are loading up with fuel. The cats with the air injection tube need the additional air from the airpump to work properly. I had taken mine off when I was trying to change out my H-pipe and run around for a couple weeks and the car ran horrible until i reconnected it. the car would take 15+ miles to start acting up then at 30 miles or so it would get to the point it was barely running. Then when I changed the h-pipe again no problems but i reconnected it at the same time.
you could always hollow the cats since they are not working anyways.
Chris
you could always hollow the cats since they are not working anyways.
Chris
zenboy99
Founding Member
When I ditched my smog stuff, my car backfired a couple of times the first day I drove it. Then the computer must have figured something out and corrected it.
Same thing happened when I got my JMS chip put in that took out the tip in timing retard. The first couple of hard 1-2, 2-3 shifts I made the car backfired, but then never again.
Same thing happened when I got my JMS chip put in that took out the tip in timing retard. The first couple of hard 1-2, 2-3 shifts I made the car backfired, but then never again.
gcomfx.com
Founding Member
Mine backfired alot when I had aftermarket cats installed. The muffler shop welded the smog pipe (from pump to the cat) ALMOST shut... so air would get trapped in it. When I removed the smog and sealed off the smog pipe... backfiring stopped instantly.
I just switched to an O/R and still no backfiring.
I just switched to an O/R and still no backfiring.
on foxes (not sure about SN's), the check valve on the smog line (it saves the pump in the event of a backfire) can quell the noise of a backfire.
also, i have not confirmed it, but every now and again someone will post that the puter takes into consideration the air volume that the pump should be injecting with regard to A/F trim at the lambdas. w/o that air injection, it can create calibration issues. i have no data to back that last part up.
good luck with it.
also, i have not confirmed it, but every now and again someone will post that the puter takes into consideration the air volume that the pump should be injecting with regard to A/F trim at the lambdas. w/o that air injection, it can create calibration issues. i have no data to back that last part up.
good luck with it.
gcomfx.com said:Mine backfired alot when I had aftermarket cats installed. The muffler shop welded the smog pipe (from pump to the cat) ALMOST shut... so air would get trapped in it. When I removed the smog and sealed off the smog pipe... backfiring stopped instantly.
I just switched to an O/R and still no backfiring.
Im pretty sure it does have something to do w/ the smog, maybe the ends are not sealed off enough where that tube connected to before and air is leaking out and causing a back fire since there is no vaccume in there anymore.
HISSIN50 said:
That makes more sense. On that tube that connects from the H pipe to the Headers there is a one way valve that only allows air to go one way. The tube is going to be hell trying to fit back down into there but were going to try and just use a black hose and clamp that valve on one end and clamp the hose on the end of the H pipe, if this works then we will know that it must have been the disconecting of the tube that was causing the back fire.
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