Piston Slap: There’s a Misfire on the Frontier!

Nate writes: Hi Sajeev, You asked for some emails, so here's one from me. It may not be Piston Slap worthy, but it's got me confused. Here's my problem: I have a 1998 Nissan Frontier. 150k miles, 2.4l four banger. It threw a Service Engine light on me the other day. The code is a P0301, i.e. cylinder #1 misfire. Figuring it was a spark plug issue, and since I was about due for a tune up anyway, I replace the plugs, wires, distributor cap and rotor. I cleared the code with my scanner, and….it came right back. I did a little creeping on the Nissan forums, and the consensus seems to be that this results from clogged EGR passages. So this past weekend I decided to clean them. I was lead to believe that this would be a cake walk. All that was required was to remove the set screws between the intake runners, spray some carb cleaner in there and scrub them out. Easier said than done. Removing the screws was not too bad, but putting them back in after cleaning was nigh impossible. 5 hours and sawed off 8mm Allen wrench later, I had the plugs back in. My truck ran great! For 20 minutes. Then the code came back. Now I'm pretty much flummoxed. The way I see it, my options are: 1. Remove the air cleaner assembly and manifold screws again and try cleaning them more thoroughly with a pipe brush and more carb cleaner 2. Try something like Seafoam through a vacuum hose. I am reluctant to do this as I'm not 100% sure which hose to use and opinions on Seafoam are mixed 3. Take my vehicle to a mechanic for a more professional diagnosis. I do have access to a reputable independent mechanic who specializes in Nissans and Toyotas So, what do the B&B think? Anyone else had this problem with a Nissan KA24DE 4 cylinder? Thanks for your help. Sajeev Answers: Looking at the picture above makes me long for the days when we had an assortment of small pickups in these United States, but we all know these older rigs will never die. And here's proof. All three of your options are valid, the armchair quarterback in every TTAC reader can't argue with that.  In my experience with the dreaded cylinder misfire code is that a multitude of wear items are at fault.  What truly matters in this case is the truck's mileage both on the odometer and at the gas station. If your oxygen sensors have over 100,000 miles on them, replace immediately.  And don't skimp, get a brand name like Bosch or the factory Nissan stuff. If nothing changes and you also feel like fuel economy isn't optimal (only you know your driving style, etc) for your commute, then maybe even a bad fuel injector is to blame. My point is that many items are behind this problem.  Which truly sucks, especially if you have multiple trouble codes present.  My recommendation? 1. If you have ANY doubts about your previous work, remove EGR and clean passages with everything from a screwdriver to toothbrushes with plenty of carb cleaner. And wear gloves, for sure. 2. Replace oxygen sensors, both of them.That's part of a complete tune up. Ditto the PCV valve. 3. Grab a piece of new rubber vacuum line and note its physical properties.  Then replace every hose under the hood that is too soft, too hard, too glazed, or anything else. Since you aren't afraid to get your hands dirty, just spend $15 for new hoses and replace them all. 4. Seafoam through the PCV valve (probably the ideal place) if so desired.  We all know the pitfalls with Seafoam, but I will admit that it's worked for me on several occasions. If all of this fails, get to your mechanic and tell him all the hard work you did.  Best of luck…not that you need it. I suspect you are almost done. Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you're in a hurry. from The Truth About Cars http://www.thetruthaboutcars.com

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