backfiring help!
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Joined: Mar 2003
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backfiring help!
My 2.8 L v6 1983 ford ranger backfires, not when reving up, but only on the way down. It does this when I shift gears, or pretty much anytime the rpms are high and the gas is let off quickily. I have replaced the egr valve, checked all of the air valves attached to the air pump, cat and manifolds, and adjusted the carbuerator prefectly but only to find no change at all. Could this be caused by a bad air pump? Another idea I had was it could be the o2 sensor on the drivers exhaust manifold. Any help would be greatly appreciated!, the small local ford dealership couldnt figure it out so its kinda frustrating.
Thanks,
paul
Thanks,
paul
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
backfiring help!
Never mind.
Two ideas to check:
There should be a 'gulp valve' that chokes off the output of the air pump on decel. Otherwise, you get backfire out the exhaust... It has a vacuum diaphragm, and uses manifold vacuum to divert the air to atmosphere. Sometimes, they made all the control valves into one combination valve.
The second thing to check is your idle speed. The throttle plates may not be allowing the manifold vacuum to build high enough on decel to operate the gulp or 'diverter' valve.
Ok, I lied,
The third thing to check is your vacuum hose routing. Yeah, the *Ford Dealer* checked it out, but they hired whoever walked in the door... And he/she was being paid by the job. You are not, so can take all the time you want in making sure that the hoses are hooked according to the underhood decal. Do it yourself. Send me the money.
tom
Two ideas to check:
There should be a 'gulp valve' that chokes off the output of the air pump on decel. Otherwise, you get backfire out the exhaust... It has a vacuum diaphragm, and uses manifold vacuum to divert the air to atmosphere. Sometimes, they made all the control valves into one combination valve.
The second thing to check is your idle speed. The throttle plates may not be allowing the manifold vacuum to build high enough on decel to operate the gulp or 'diverter' valve.
Ok, I lied,
The third thing to check is your vacuum hose routing. Yeah, the *Ford Dealer* checked it out, but they hired whoever walked in the door... And he/she was being paid by the job. You are not, so can take all the time you want in making sure that the hoses are hooked according to the underhood decal. Do it yourself. Send me the money.
tom
Freshman User
Joined: Apr 2003
Posts: 38
Likes: 0
From: Texas....
backfiring help!
I would change the spark plugs and use the Bosch platinum series. Did you recently change your distributor wires? If you did then I would go with the obvious and check to see if your pistons are firing in order. (It would probably backfire though upon ignition, not under driving speeds) I am a mechanics son not a mechanic but I always start with the basics.
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