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Help with Engine Code After Tune-Up

960 Views 10 Replies 5 Participants Last post by  SoCal2V
Hello All,

I am looking for some advice on my situation. I have a 96 Mustang GT and after having it garaged for over a year without moving it, I decided to drive it again. I put the key in and it turned on like nothing. Two days later without doing anything at all, I took it to the smog check station and failed. The numbers were not bad and I decided to do a few things and try it again.

So I changed spark plugs, fuel filter, air filter and oil filter and oil and two oxygen sensors. Before this there was not any problems only that it did not pass the smog test and there was a sort of a fuel smell coming from the engine as if it was not burning the fuel properly but no leaks.

Right after I finished doing all the repairs I turned it on and the Check Engine light started to flash and stayed on. The light was not there before.

The car has only about 175K miles, the fuel smell is no longer there, the timing is great engine sounds great, I drove the car already about 120 miles including highway and streets including a big grade on the hwy and the car feels great.

This morning I took it to Pepboys to get a reading on the code and it came back as a P0301 Cylinder 1 misfire detected. I'm not sure if anything of the things I did to the car would cause to misfire.

One last thing, after I noticed the check engine light on, I went to check the spark plug cables and there was one cable that snap into place (facing the car, it was the deep right side one). Again, not sure if that is the case, but again, the car is running great.

Any advice, suggestion would be greatly appreciated. Thank you.

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Check the plug and the wire at #1 for a secure connection to the coil and the plug.

Is the cel still flashing? Did you have the code cleared? If so, has it come back?
The new plug could have been dropped in shipping and have a hairline crack. Has happened to me more than once. Pull plug 1 and check it out
+1 to the above. Also could have a crack in the porcelain insulator from when you installed it, sometimes the socket doesn't hold the plug right. Either way, it would only take about 2 minutes to unscrew it and take a look.

Use an old plug to check the fit of the wire onto the plug. The boot slides on the wire and, if the boot is too low on the wire, then the wire clip won't snap onto the plug properly.

Get a wiring diagram (Haynes manual is about $20 and the schematics are pretty good) to figure out what that green wire is. Green is usually a ground wire but not always.


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Thank you for all your replies. I cleared the code about a week ago and I've driven the car about 300 miles since then and the code has not come back.
I'm not sure if I should start another thread but here is another question. Like I mention before the reason I am did all the fixes was to take it to the smog test only station...After i did everything mentioned before, I took it and still did not pass and I surprised that the emission numbers were pretty much the same.
Now I have noticed a difference in the engine and it sound great no gas smell like before from the engine, but now it looks like more steam, based on smell is coming out of the exhaust, specially the one opposite from the new two oxygen sensors. Once I start running it goes away but I've never seen it this much and for that long. I know it goes away but it's just too much. For example, I take my daughter to school and I run about 14 round trip miles total, at the stop lights I can see the steam coming even after 5-6 miles, once I start running it goes away, then when I get home I leave on idle go check and I don't see anything, then I turn the engine off, leave off for like 30 seconds, turn the engine on and I see the steam coming slowly from the exhaust again more on one side, this time not as much but still there, I smell it and smells like steam.
Coolant levels are fine and oil levels are fine too....Any suggestions???
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The steam is condensation. It comes two ways - at startup, the exhaust pipes heat up and burn off moisture that collects while the car was shut down. Next, catalytic convertors..... What do they do?? They convert carbon monoxide and hydrocarbon exhaust emissions into water vapor.

What your car is doing, by the way you describe, sounds completely normal.

Why did it fail smog? Did the technician provide any recommendations on what the car might need done?
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Thx for the reply SoCal2V, the tech did not recommend anything since this is a Test only he said he could not repair or suggest anything, The car failed emission at the lower speed 15MPH but passed at the 25MPH. All the Visual Control Inspection passed...Here are the results:

15MPH RPM 1324

CO2 11.72
O2 4.15
HC (PPM) 202 allow 52
CO (%) 0.44 allow 0.49
NO (%) 1088 allow 424

At 25MPH RPM 2248

CO2 12.80
O2 2.87
HC (PPM) 36 allow 36
CO (%) 0.10 allow 0.46
NO (%) 105 allow 711

I'm not sure what to do next other then try those fuel cleaners and things like that. I really don't have the finances to take it to a smog shop. Any recommendations?
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From the looks of your smog test numbers, the failure is likely due to underperforming cats.

You could try one of those bottles of "guaranteed to pass emissions test" stuff..... Honestly though, I have no idea how or if that stuff works.

Next option, if you're into doing some gangsta sh!t, is the smog test industry here in beautiful Southern California is ripe with individuals who lack professional integrity and will help you pass for a nominal fee. For legal reasons I cannot and am not recommending going this route:winks Just sayin'....

The real fix is most likely new cats though. Keep an eye out on Craigslist; we live in different areas (I view the Inland Empire listings, yours would be Los Angeles) but every so often I see stock catalytic midpipes listed for anywhere between $150-300. Or have new cats installed, which doesn't sound like is in your budget at the moment.

Something else worth trying is take your smog printout to a smog repair shop and ask them if they have any ideas; there's a good chance that somebody who actually does emissions testing for a living would know something I don't.
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The IE Eh? I have TONS AND TONS of friends in the IE. Chino, Chino Hills, Temecula, that general area.

Even some down in Fallbrook.

I liked it down there, other then the wacky ass peopleand the motor cycles passing people at high speeds between cars on the highway.

I played a club in Riverside when I was down there, as well as a place in SanD and a radio show out of FallBrook. Then kinda messed around at a few record stores in LA. That was my week long Cali tour. Lol.
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Haha, yeah I'm about 20-30 minutes north of San Bernardino/Riverside; little place in the desert called Pinon Hills. Used to hang in Chino Hills like waayyyy back in the day when my grandparents had a place in the Carbon Canyon section of Chino Hills. You in a band or something?

Lol, who broadcasts out of Fallbrook? That place is way the fk out there. Although I wouldn't mind living there, nice area, love north San Diego county... Think Tony Hawk had a house there for a while.
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