5.0 engine Help! - Northern California Ford Owners

This is topic 5.0 engine Help! in forum Tech Talk at Northern California Ford Owners .

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Posted by Quick 88LX (Member # 1950) on :

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 ]

Posted by 66 AC COBRA (Member # 904) on :

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

Posted by Black94 5.0 (Member # 655) on :

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....

Posted by Quick 88LX (Member # 1950) on :

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

Posted by 66 AC COBRA (Member # 904) on :

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]

Posted by Quick 88LX (Member # 1950) on :

Well if I could have a definite hook up on smog then I will begin ripping out all of the equipment tonight!

Posted by Quick 88LX (Member # 1950) on :

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]

Posted by 66 AC COBRA (Member # 904) on :

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 [Razz]

Posted by mustanggt5091 (Member # 444) on :

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]

Posted by Quick 88LX (Member # 1950) on :

Jeff, you will owe me a days worth of help if your guys don't come through for me man. [Wink]

Everything is comming off tomorrow

Posted by hidnn.o.s. (Member # 1219) on :

My guess is your plugs

Posted by saleenfan (Member # 1605) on :

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.

Posted by Black94 5.0 (Member # 655) on :

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]

...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! [patriot]

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