Mysterious misfire

[pmiller101]

OK, I have a '96 Beretta with the 3100 engine with 192k and it has developed a misfire which I cannot pin down. While it is idling it will randomly stumble and recover repeatedly. While driving it will feel like it is misfiring badly around 50-60 mph.

The plugs are new and have been changed twice, the wires have been checked out and are fine. (I replaced them with a new set and the misfire didn't go away) The resistance on the coils checked out ok, all within spec. So I ran a vacuum test and it is kinda low around 18 and dips down to 17 when the engine stumbles.  No vacuum leaks that I can find. Compression checked out ok on all 6 cylinders, all between 210 and 220.

The only code that I keep getting is PO441 which is the Evap Purge flow, so I tried disabling the whole purge system and capping the vacuum lead to the plenum but that made no difference to the misfire/stumble. Would that even have anything to do with it?

So I am stumped, oh yeah I also checked into the fuel rail and that was clean as were all the injectors, no obstructions. Fuel filter is new as of 2 months ago. When you step on the gas it will still run hard so it doesn't seem to be starving for fuel. Anyway I am stumped, anyone know what I might have overlooked or what it mgiht be? Thanks.

[1988GTU]

(pmiller101 @ Aug. 10 2006,00:45)Q
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EThe only code that I keep getting is PO441 which is the Evap Purge flow, so I tried disabling the whole purge system and capping the vacuum lead to the plenum but that made no difference to the misfire/stumble. Would that even have anything to do with it?
I would think if you disabled this with no change in the end then it must be with this part being faulty.

I am just shooting in the dark though.

[Guest]

I have all the the same problems that you are having and I have done  the samethings except unpluging the whole purge system
whats the purge system and how do I do that..
how do I do that then I can tell you what I find out...
I think that my fuel pump is going bad but not for shore...

[yellow3800]

dirty egr system, valve?  that purge code... is it the fuel canister purge solenoid?  Just wondering, if this solenoid goes out [on my 3800 it will cause all sorts of "quad driver" problems and car will run like junk] will it drag anything else down with it?

I'm not too familiar with po codes, so I can only shoot from the hip.  Anyone else?

ps, unplugging a solenoid does not good because there is a given resistance [variable too] that the computer needs to see.  Unplugging it would only gaurantee trouble.

[Guest]

I Thank it night just be my fuel pump going out. when I bought the car in Feb the pump was replaced with a make sheft one. They took a pump from another car and made it work I think that its about done. but the car runs great after starting with a little miss.

[Decipha]

don't overlook your injectors... perhaps one of your injectors is failing, try ohming it out when cold, run the car until it starts missing badly and ohm them out again