Piston Slap: The Gassy Dart, the Bosch-eating Magnum

Sajeev Mehta
by Sajeev Mehta

TTAC reader sportsuburbanGT writes:

Hi Sajeev,

Have a couple of questions: I have a 72 Dodge Dart that I am performing a 318 to 340 swap. It’s taken longer than I planned (lack of time), I backed the car in the garage 2 years ago and now I am planning on firing it up in this April. The question is the gas: I had about a half tank when I backed it in, and I put some Stabil in the tank, but I took the cap off to try a new cap and the tank smelled really awful. I replaced the fuel filter, but should I drain the tank and refill with fresh gas, put some fresh gas in the tank to mix up what is in there, or pull the tank have it boiled out and refill. I was driving the car up until March 2009, and I put that last half tank in there in March 2009. I am in Long Island, NY so we have that crap gas till April.

My second question is on my (daily driver) 2005 Dodge Magnum RT, with 87k on it. I replaced the O2 sensors (all 4) as preventative maintenance and now I keep getting a p0152 code. It’s the code for the upstream right side O2 sensor. I installed new Bosch sensors, but I received the first CEL right after I started it up after the new sensors were installed. I replaced the right upstream with a new unit (Bosch), no code on start up. The CEL came back after 4 days and 300 miles, stayed on for a day then went off for a day and came back this Sat and is still there. I disconnected the neg. battery before I performed this work. I replaced the sensors as preventative maintenance; I was under the impression they last for about 100k. I also have the Mopar Performance long tube headers with a Borla exhaust on the car, they have been there since about 15k. Is the Magnum eating O2 sensors, or are these Bosch sensors no good?

Great write ups, I have really enjoyed reading them, thanks in advance for any help.

Sajeev answers:

I like your tastes in cars, this brand loyalty proves why some (Detroit) brands need not stray far from what made them so popular in the first place. Not that we all need Dodge Darts in lieu of a Toyota Prius, but that’s not the point…

The Dart: I really can’t decide between 100% fresh gas or diluted with fresh gas. It also depends on if you plan on a carburetor rebuild/upgrade in the future. I think it’s less work to buy a several fuel filters and replace as needed, carefully (low RPMs, please!) driving the car until the old stuff burns off. But that’s because I absolutely loathe messing with gas tanks. And, once again, you might need to re-jet the carb to compensate for the extra cubes, so who cares if you get junk from old fuel in there?

The Magnum: if the wiring does not look frayed/melted, get a new sensor, it should be warrantied at your parts store. I have Kooks headers on my ’95 Mark VIII and I love my “non-factory” Bosch O2 sensors for a Ford truck. These have been very good to me for over 5 years and 40,000 miles. But others have complained on the forums, for reasons I can’t logically understand. But then again, I only have one sensor per exhaust bank.

sportsuburbanGT answers:

Thanks for the pointers. I will replace the O2, I hope three times is a charm. The wiring is mint, it is nit hitting or rubbing anything. I will also go for the fresh gas in the Dart a little of the summer blend 93 should do the trick.

That Mark sounds sweet.

Sajeev concludes:

Oops, I mis-read your comment. If that’s your third O2 sensor, I’d look much, MUCH closer at the wiring harness. It’s amazing what little contact it takes to melt those wires against a set of long tube headers, especially if you doubt the skill of the installation. If the wiring checks and there’s no other trouble codes, consider the OEM-branded replacement sensor. I can’t imagine any other problem creeping up so quickly after installation of your first set of Bosch sensors.

And yes, its modifications like yours (ours?) make my Mark so much fun to drive, so difficult to sell in the face of more modern, far superior iron. I’m sure you know the feeling. Good luck to you.

Send your queries to mehta@ttac.com. Spare no details and ask for a speedy resolution if you’re in a hurry.

Sajeev Mehta
Sajeev Mehta

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  • Texan01 Texan01 on May 19, 2011

    I bought a Contour that had sat for 2 years with a 1/2 tank of gas. I had wondered if it would start after I charged the battery back up, considering the ancient gas. It started right up, and stank to high heaven thanks to the stale gas, put fresh gas in it and it did just fine, stopped smelling after the 3rd tank.

  • Rpn453 Rpn453 on May 19, 2011

    Replacing O2 sensors as preventative maintenance doesn't make sense to me. I've seen them go 200k+ miles with no fuel economy or operating issues.

  • CanadaCraig You can just imagine how quickly the tires are going to wear out on a 5,800 lbs AWD 2024 Dodge Charger.
  • Luke42 I tried FSD for a month in December 2022 on my Model Y and wasn’t impressed.The building-blocks were amazing but sum of the all of those amazing parts was about as useful as Honda Sensing in terms of reducing the driver’s workload.I have a list of fixes I need to see in Autopilot before I blow another $200 renting FSD. But I will try it for free for a month.I would love it if FSD v12 lived up to the hype and my mind were changed. But I have no reason to believe I might be wrong at this point, based on the reviews I’ve read so far. [shrug]. I’m sure I’ll have more to say about it once I get to test it.
  • FormerFF We bought three new and one used car last year, so we won't be visiting any showrooms this year unless a meteor hits one of them. Sorry to hear that Mini has terminated the manual transmission, a Mini could be a fun car to drive with a stick.It appears that 2025 is going to see a significant decrease in the number of models that can be had with a stick. The used car we bought is a Mk 7 GTI with a six speed manual, and my younger daughter and I are enjoying it quite a lot. We'll be hanging on to it for many years.
  • Oberkanone Where is the value here? Magna is assembling the vehicles. The IP is not novel. Just buy the IP at bankruptcy stage for next to nothing.
  • Jalop1991 what, no Turbo trim?
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