1993 Dodge Intreped Spark Plugs ?

[Market525]

I'd like to run an odd problem up the flag pole to see what you guys think ....
While tuning up a friend's 1993 Dodge Intreped I encountered a problem that I've never seen.

The car has 120,000 or so miles on it, and probably has not followed a strict maintenance schedule, just from looking over the engine bay.

Before the tune up, the car cranked & idled just fine. Standing at the rear of the car, you picked up a pretty strong "raw fuel" smell. Inside of the tailpipe was dark & sooty.

Upon pulling the spark plugs, the driver's side of the engine's plugs looked perfectly normal. Pulling the passenger side of the engine, all three plugs were black with a fairly dry soot. Cylinder 1 spark plug was worse than the other two, almost completely fouled. But all three on that side was in very bad shape.

Another observation, the engine oil was jet black and had a slight fuel smell to it.

Again, the car started fine & idled smoothly before this tune up. I also cleaned the throttle body (unsure if it's ever been cleaned before) and it too had alot of rich, black buildup inside the TB.

The spark plug issue on one engine bank only baffles me. Any thoughts out there?

 

[W.T.McGlynn]

Could it be the Injectors if one bank is common and not multi-port.
Just a thought.

 

[The_Jeff]

Maybe there's a vacuum leak on the drivers side and the 02 is richening all six cylinders? Does this thing have one MAF then dual throttle bodies?

 

[buddy-lee]

The early Dodge Intrepid series 1993-97 had dual throttle bodies and TP sensors. Two separate banks o2 sensors were used just ahead of the catalytic converters. If you have access to a code interpreter (factory or Haynes manual) then you can pull up trouble codes on most 90's Chrysler vehicles by rapidly turning your ignition key to "run" (not start!)position, then fully off, 3 times with the 3rd time leaving key in "run" position and the check engine light will begin to blink shortly, example: 1 blink, pause then 2 blinks, (longer pause until next code) means battery was disconnected in the last 100 or so start cycles... 5 blinks, pause, 5 more blinks means end of code cycle and it will restart readout again. You will at the very least get a 5-5 code, any of which you can compare to your manual.
Regardless, your overly rich running and soot is very likely a pegged o2 sensor on that bankside. Before you replace, there are some basic tests on some of these sensors that auto parts store minimanuals cover (some were free)along with their basic crude code readers,one of which I think is by an aftermarket company called Wells Corporation. BTW, the Dodge also uses a MAP sensor instead of a MAF. Check for obvious vacuum line breaks and disconnects as well. Your gas smell and soot everywhere is raw unburned and partially burned fuel contaminating the works. Remember to use "antiseize" aluminum compound paste on sparkplugs and sensors and don't overtighten, but only to specs. This would be a great time to replace ignition wires as well, with OEM or equivalent quality, as they are only factory rated for 60k miles. Good luck.

[ November 07, 2004, 05:45 PM: Message edited by: buddy-lee ]

 

[Market525]

Buddy-Lee,
Thanks for your thoughtful reply. I could be going crazy, but I think the car has only a single throttle body! I will check tomorrow. Your 02 theory makes sense; but wouldn't it cause a "check engine" light?

As for vaccum hoses, I failed to mention that the fuel pressure regulator vaccum line was very deterioated, and had a small vaccum leak. I replaced the hose. The PCV hose was pretty badly cracked, but I could not hear a leak. I replaced both the PCV valve as well as the hose.

I do have plans to replace the plug wires this week, and will follow up on what I find & do. Thanks to all who replied.

Steve

 

[Market525]

As it turns out, the 3.3 does have a single throttle body. Looking at the Haynes manual, the 3.5 has dual.

On oxygen sensors, looks like one sensor is located in each RH & LH exhaust manifolds. That being said, when I checked the codes today, it gave me code 51, which shows (according to the Haynes manual) a LEAN fuel/air ratio condition during engine operation. Code 52, had it shown, would have been for a RICH mixture.

Now I'm really confused - this does not coincide with the one bank of very sooty spark plugs -- I was expecting a code showing a rich mixture. Or do I just not understand this situation correctly?

Any comments?

 

[rshaw125]

So is the engine in question a 3.3 or the 3.5?

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