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Skipping and misfires


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12 minutes ago, Ωhm said:

Engine SCANNER? OPEN/CLOSED Loop? O2 switching? Somethings is giving you extra fuel.

I don't have an engine scanner for a 1991 HO engine.  The key method with the Check Engine Light shows codes 55 and 12.  The O2 sensor was changed about 2 weeks ago.  How do you check for an Open/Closed Loop?

 

Thanks,

Tom

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To check open and closed loop is on the scanner, those codes are codes Chrysler cars all have, 55- end of codes 12 battery disconnected. How's the exhaust look?
Has it stumbled since the plug change?

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8 minutes ago, jdog said:

To check open and closed loop is on the scanner, those codes are codes Chrysler cars all have, 55- end of codes 12 battery disconnected. How's the exhaust look?
Has it stumbled since the plug change?

As I said, I don't have a scanner? for this engine or anything older than OBDII.  The exhaust appears to be ok.  The battery was disconnected while I was working on the engine.  It is too early to tell if the plugs fixed the intermittent stumbling problem.  I only changed them about a week ago, and I have driven it once since then.

Edited by HellCreek
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15 minutes ago, HellCreek said:

Ok, you've lost me.

Most Diagnostic Manuals have a "NO CODE or PASS" path. Basically it just tell you to replace everything until problem goes away. It does however start with things that are not part of OBD testing. Example: Secondary ignition (weak coil/carbon tracks in cap, wires & plug), Incomplete combustion, Air leaks, Fuel leaks and ends with replace ECU.

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1 minute ago, Ωhm said:

Most Diagnostic Manual have a "NO CODE or PASS" path. Basically it just tell you to replace everything until problem goes away. It does however start with things that are not part of OBD testing. Example: Secondary ignition (weak coil/carbon tracks in cap, wires & plug), Incomplete combustion, Air leaks, Fuel leaks and ends with replace ECU.

Replacing everything is what I have been doing.  I have not replaced the coil , yet, but wires and plugs have been changed.  I cannot see any fuel leaks.  The exhaust odor is not really like Raw Gasoline, such as you would smell at the pump when filling the tank.  It is more like you said, "incomplete combustion".  putting it a different way, if I lived in California, it would not pass the emission tests.

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2 minutes ago, Ωhm said:

One source for excess fuel can come from the Fuel Pressure Regulator (FPR). Check hose between FPR and manifold for fuel/fuel vapors. 

Fuel Pressure regulator is new as is the fuel rail - all new o-rings.  Have I mention that this was an exhaust odor and not coming from the engine bay?

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  • 2 weeks later...

Well, the surging problem seems to have been fixed, though I am not completely sure, since it is intermittent.  Thanks for all of the help on this.

 

I do have one more question:  the fuel pump is very loud, even driving down the road.  Is that normal?  I thought that the ballast resistor had something to do with quieting it down once the engine was running or something.

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Some pumps are definitely louder than others. I put a Delphi in one of mine and after it came loose from the crude side-of-the-road hose-clamp hold in, and started pulling fuel from the middle of the tank (nothing screws with you quite so much as running out of gas at 1/2 tank...) it got changed out for a Bosch unit. The Bosch is much quieter. 

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4 hours ago, jdog said:

What pump did you put in there?

It is a Delphi.  The first one that I installed was a Precision from O'Reilly's, but the little hose blew off that one.  I installed hose clamps on the Delphi.  I did a pressure check at the fuel rail shortly after I posted to this thread, and the readings were spot on to the specs.

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