Re: RE: Re: Engine backfire on deceleration

From: BlackDak93 (stephen.barnett@worldnet.att.net)
Date: Fri May 28 2004 - 23:21:52 EDT


Thanks again Bernd,

I hear there is a "dye" test that can be performed to check for oil in the
belly pan. I have looked inside the manifold, and it is pretty oily. I would
expect it to be fairly clean. I don't know if this is a good indicator or
not. I would guess over time you might see an oily buildup from the PCV
valve.

""Bernd D. Ratsch"" <fasstdak@hotmail.com> wrote in message
news:001301c44505$9a830f90$020aa8c0@bernd...
>
> Here's what happens on deceleration:
>
> (1) Fuel is cut after approximately 1 second (MAP and TPS control this)
> (2) When you step on the pedal again, after deceleration, you go full rich
> for approximately one second which causes the back fire.
>
> If you're really running lean (as with a blown plenum gasket) the PCM is
> already in a richer than normal state which adds to the backfire - unburnt
> fuel in the exhaust.
>
> O2's are ignored on decel and WOT.
>
> - Bernd
>
> -----Original Message-----
> From: owner-dakota-truck@bent.twistedbits.net
> [mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of Biff Byrum
> Sent: Friday, May 28, 2004 1:20 PM
> To: dakota-truck@dakota-truck.net
> Subject: DML: Re: Engine backfire on deceleration
>
>
>
> I would suggest anything but the belly pan gasket. It's nothing more than
> unburned fuel. Just look at anything involved in firing the engine, except
> timing. That's not settable beginning that year. Best guess would be O2S.
> Also EGR. Do you know how to test the EGR? With a hand vaccum pump it's
> simple. But the O2S sounds like the likely problem. Biff
> ----- Original Message -----
> From: "BlackDak93" <stephen.barnett@worldnet.att.net>
> To: <dakota-truck-moderator@bent.twistedbits.net>
> Sent: Friday, May 28, 2004 8:35 AM
> Subject: DML: Engine backfire on deceleration
>
>
> >
> > My 93 dakota 5.2L backfires and pops and rumbles when ever I let off
> > the
> gas
> > or just as I apply throttle after coasting. I have a couple of shops
> > look
> at
> > it, but no success. I also am getting a fair amount of "pinging." even
> > on premium gas. I suspect the infamous belly pan gasket is leaking. My
> question
> > is, could a leaking belly pan gasket cause this backfire? Does anyone
> > have any suggestions for other possible causes/cures for this
> > backfire?
> >
> >
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>



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