Yes, and no. You can experience "backfires" or "burbling" through the
exhaust with aftermarket systems and/or aftermarket cat's. The CA machines
won't detect a blown plenum gasket unless it's severe enough for the PCM not
able to adjust the fuel properly.
On decel, you initially go full rich and then full lean (injectors shut
off). When you step back on the pedal, it goes full rich and then adjusts
to normal range again...causing a slight pop if you decel again.
A very light film of oil on the base of the plenum is normal...anything more
(or extreme enough to leave a puddle of oil) requires replacing the plenum
gasket.
- Bernd
-----Original Message-----
From: owner-dakota-truck@bent.twistedbits.net
[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of
orange383@comcast.net
Sent: Sunday, May 30, 2004 2:15 PM
To: dakota-truck@dakota-truck.net
Subject: RE: DML: Engine backfire on deceleration
Ok, the cap, rotor, wires and plugs are all new so I suppose it would narrow
it down to the belly pan gasket. Assuming this to be the problem and
causing a lean condition would that only cause it to run lean when
decelerating or coasting? I ask because I just had it smogged (CA new dyno
smog) and it passed perfectly fine, but the catalytic converter is fairly
new. It was replaced the same time as the cap, rotor, wires and plugs.
Actually, it never did this before I replaced everything. The converter is
a high flow Carsound model. Could that possibly just make it more apparent
due to the loss of backpressure? Thanks again.
David
>
> it could have sucked the gasket in on the belly pan and is allowing
> air to
> create a vacuum leak. this could create a lean condition contributing to
> deceleration backfire......
>
> The first thing I'd do is swap the cap and rotor, check the plugs for
> a lean
> condition, and see if the wires need replaced......electrical misfires can
> cause backfires during acceleration and deceleration
>
> if it's running lean that will surely cause the backfire too.....there
> are
> other causes too, but these are the major culprits.
>
> Ron
> 01' Dakota Sport 3.9 4WD
> http://www.scsilverdak.1colony.com
>
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