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Author
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Topic: 5.0 engine Help!
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Quick 88LX
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Member # 1950
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posted
 
 
Okay, the problem is an exhaust backfire. One loud backfire if I get on the throttle and then let off to shift or just let off in general. What do you guys think is my problem? Fuel pressure? Timing? Vacuum leak? Exhaust leak? I am not getting any check engine light at all.
My combo is:
Edelbrock Performer 1.90/1.60 heads
Performer intake
STOCK cam and STOCK 19lb injectors
Aeromotive AFPR
Full off road exhaust from equal length headers back
MSD ignition from the 6AL down to the spark plug wires.
I am at a loss here. I adjusted my fuel pressure from 55 static all the way down to 35 static with little difference in the backfiring. Actually, at 55 it ran BETTER than the lower PSI but the backfire still was a problem. I am thinking my injectors are not squirting enough lbs/hr?????? I don't know! This is making me angry because everything else works like a charm (except minor hesitation when the throttle is tapped)
What things should I check? I am mechanically sound so working on the car is a no brainer for me but this problem has been nagging me FOR DAYS!!!!!!!!!!! What do you guys think?
[ February 23, 2004, 05:04 PM: Message edited by: Quick 88LX ]
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"Men are Made, Not Born"
Car Picture : http://www.angelfire.com/theforce/quick88lx/
Original Member #495. Can I get my number back?
Posts: 1785 | From: Fairfield, CA/Okinawa, Japan | Registered: Oct 2002
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66 AC COBRA
Nitrous King
Member # 904
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posted
grab jeff's timing light and make sure its where it needs to be
i will be back in ff on friday so if ur still needing some help i can take a look at it
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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BlackNGold
CaliforniaFords.com
Moderator
Member # 655
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posted
Check the smog pump diverter valve...Mine was bad and would cause my car to back fire all the time....
I'm willing to bet that is it, especially if you're running 10 degrees and have no vacuum leaks....
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-SLOWER TRAFFIC KEEP RIGHT-
Posts: 5132 | From: Bay Area, CA | Registered: Dec 2001
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Quick 88LX
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Member # 1950
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posted
Thanks Eric I may take you up on that if I can't get this problem fixed by then.
Black 94: How could you tell the valve was broken?? In your case, what did you find? I will look at that also
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"Men are Made, Not Born"
Car Picture : http://www.angelfire.com/theforce/quick88lx/
Original Member #495. Can I get my number back?
Posts: 1785 | From: Fairfield, CA/Okinawa, Japan | Registered: Oct 2002
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66 AC COBRA
Nitrous King
Member # 904
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posted
shit to test the diverter
just take all the smog pump crap off, and if it goes away u know what the preoblem was, i said was, leave that shit off ![[Razz]](tongue.gif)
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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Quick 88LX
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Member # 1950
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posted
Well if I could have a definite hook up on smog then I will begin ripping out all of the equipment tonight!
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"Men are Made, Not Born"
Car Picture : http://www.angelfire.com/theforce/quick88lx/
Original Member #495. Can I get my number back?
Posts: 1785 | From: Fairfield, CA/Okinawa, Japan | Registered: Oct 2002
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Quick 88LX
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Member # 1950
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posted
Bumped up the timing to about 14 initial. It was set at 10. Sure did gain a few missing HP but the backfiring is still there. I am leaning more towards shitty smog equipment now ![[Mad]](mad.gif)
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"Men are Made, Not Born"
Car Picture : http://www.angelfire.com/theforce/quick88lx/
Original Member #495. Can I get my number back?
Posts: 1785 | From: Fairfield, CA/Okinawa, Japan | Registered: Oct 2002
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66 AC COBRA
Nitrous King
Member # 904
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posted
quote:
Originally posted by Quick 88LX:
Bumped up the timing to about 14 initial. It was set at 10. Sure did gain a few missing HP but the backfiring is still there. I am leaning more towards shitty smog equipment now
take it off, take it off, take it off
sounds like mardi gras for your motor
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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mustanggt5091
All I need is.....
Member # 444
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posted
take it off nick, keep it if your worried about it. You just smoogged your car this past year right??? You got 2 more before your next smog, i got 3 people ligned up for it already!!!! ![[patriot]](graemlins/patriot.gif)
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88 GT 357w (SOLD):(
06 Limited Edition R6 !!!!!
Posts: 2353 | From: Fairfield / Santa Rosa , Ca | Registered: Sep 2001
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Quick 88LX
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Member # 1950
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posted
Jeff, you will owe me a days worth of help if your guys don't come through for me man. ![[Wink]](wink.gif) Everything is comming off tomorrow
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"Men are Made, Not Born"
Car Picture : http://www.angelfire.com/theforce/quick88lx/
Original Member #495. Can I get my number back?
Posts: 1785 | From: Fairfield, CA/Okinawa, Japan | Registered: Oct 2002
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hidnn.o.s.
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Member # 1219
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posted
My guess is your plugs
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R.I.P. Willie G. You are missed on this forum
Posts: 15950 | Registered: Apr 2002
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S351-R
CAFords OG
Member # 1605
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posted
If you have cats, don't disconnect the air pump, it will ruin your cats. If you do disconnect or remove the air pump, get an off-road pipe.
Posts: 344 | From: Earth | Registered: Jul 2002
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BlackNGold
CaliforniaFords.com
Moderator
Member # 655
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posted
quote:
Originally posted by Quick 88LX:
Thanks Eric I may take you up on that if I can't get this problem fixed by then.
Black 94: How could you tell the valve was broken?? In your case, what did you find? I will look at that also
Well, I at first I thought I had a bad tune with all the bolt ons and a shitty 94 EEC...I tested the diverter valve by blowing through it, and it seemed to be functional with the air pressure my lungs could supply ![[Big Grin]](biggrin.gif) ...Then there wasn't anything else to bolt on except heads and cam and I couldn't afford those at the time...So, I decided to shave some weight and gain a little horse power...
Basically, I took off the smog pump, diverter valve and smog hoses and used a rubber expansion plug to plug the tube comming off the back of the heads...PROBLEM SOLVED!
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-SLOWER TRAFFIC KEEP RIGHT-
Posts: 5132 | From: Bay Area, CA | Registered: Dec 2001
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