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Discussion Starter · #1 ·
I have a 2000 LX that just started running rough and idling off a couple days ago. I am getting code P0300. I actually stalled out a couple of times when sitting at a stop light. I was advised to change plugs and wires but I dont want to do this work and it be something else. Any suggestions? Or should I just stick with changing the plugs and wires. I also have been getting code P0457 and have changed the gas cap 3 times. Code still pops up periodically.
 

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I have a 2000 LX that just started running rough and idling off a couple days ago. I am getting code P0300. I actually stalled out a couple of times when sitting at a stop light. I was advised to change plugs and wires but I dont want to do this work and it be something else. Any suggestions? Or should I just stick with changing the plugs and wires. I also have been getting code P0457 and have changed the gas cap 3 times. Code still pops up periodically.
ISSUE • DTC Diagnostic Trouble Code
Some vehicles may exhibit a Malfunction Indicator
• EVAP Evaporative Emissions System
Lamp (MIL) illuminated with Diagnostic Trouble
Codes (DTCs) P0442, P0455, P0456, P0457 or • EVMV Electronic Vapor Management Valve
P1442 or a "Check Fuel Cap" Lamp illuminated with • FTP Fuel Tank Pressure
DTC P0457 for the Evaporative Emission System. • MIL Malfunction Indicator Lamp
This may be caused by loose or leaking hoses.

I would start with the above and not do plugs or wires. The above could explain random misfire, much like vacuum leak.

-chart-
 

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misfire

So what is the P0300 code? They said it was ignition. wouldnt that be plugs, wires or coil?
Random misfire is likely lean or excess EGR flow. Plugs, wires, or coil will likely be specific misfire and will be 301 for cyl 1 and 302 for cyl 2 etc.

Random misfire and rought idle can come from excess vapor from the fuel system going into the manifold, or a leak that lets it put air into the manifold rather than gas fumes.

Misfire does not mean it had no spark. It is detected by a change in rpm of the crank pos sensor. Certain roughness may key a misfire detection that is not really a misfire, but tells you you need to fix something.

-chart-
 

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Egr

So should I replace the EGR valve?
NO. If the EGR was not working you would have a 400, 401,402 code.

More likely a vacuum leak. Any hose that hooks to the intake manifold could be suspect. PCV elbow is classic for the DOHC engine.

And any hose that hooks to the accordian hose between the air filter box and throttle body.

Any hose that hooks to the vacuum manifold, the black box on the firewall, driver side, with big hose to the brake booster, and big hose to the intake.

-chart-
 

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Discussion Starter · #7 ·
New Codes

I stopped by autozone on my way home today and had the codes checked again. Now I am getting codes P0171 and P0174. They say can be MAF sensor or fuel pressure or o2 sensor. Where to begin. I did get a code a few years ago for the o2 sensor and never replaced it. Do you think thats what it could be now?
 

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I stopped by autozone on my way home today and had the codes checked again. Now I am getting codes P0171 and P0174. They say can be MAF sensor or fuel pressure or o2 sensor. Where to begin. I did get a code a few years ago for the o2 sensor and never replaced it. Do you think thats what it could be now?
You could:
Diagnose or Throw Parts.
Parts stores and many dealers do the second.
However the wise thing to do is the first.
And in that, pays to do the easy and likely.
Easy is fuel pressure.
"Throwing parts" is O2
The O2 sensors do not do anything until they warm up.
If the car runs bad when cold and for the first few minutes, it is not the O2.
Lean is usually vacuum leak or low fuel pressure.

-chart-
 
 

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Discussion Starter · #10 ·
Do you know where I can get a diagram of the vacuum hoses so I can find where the leak is? Or do you have a copy of a diagram of vacuum hoses?
 

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Discussion Starter · #12 ·
I found the hoses. I checked them from the EGR and there was no suction. Im thinking I should replace the EGR valve. What do you think?
 

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There shouldnt be any suction on the egr valve vacuum hose at idle. To test the valve, with engine idling, remove vac. hose and replace it with a piece of scrap vac. sampling hose. Suck on open end of the hose. Eng. should stumble or die signalling diaphragm is opening allowing egr (exhaust) flow into the manifold. Eng. bogs (or dies) because there shouldnt be any egr flow at idle or wot (wide open throttle).
 

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Discussion Starter · #14 ·
more codes

Now I am getting more codes for the o2 sensor and the ignition code is back along with the 2 lean bank codes. Not sure what this means. Havent done any repairs because I cant seem to find the problem and I dont want to throw parts on til its found.
 

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Did you find the vacuum diagram sticker underhood? Keep searching for a vacuum leak (bad hose, gasket, etc.). You have the vulcan engine, not the duratec, correct? Check the pcv valve hose and valve cover vent elbows. Also, check the gasket on that roundish black plastic thingy Ford calls the intake manifold air valve assy. mounted on the rear pass. side of the upper intake manifold (uim) and the firewall if equipped.
 

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Smoke it out!

There's a very easy way to find a vacuum leak. Just disconnect one of the vacuum hoses up by the throttle body or brake MC and blow cigarette smoke thru it I gaurentee that if you have a VL the smoke will seek it out fast. Make sure you block off the air cleaner( I used a plastic grocery bag on mine I just covered the filter element and reinstalled it. Obviously leave engine off. If you dont smoke go buy a cheap cigar or something. Believe me it will work. GOOD LUCK!;)
 
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