200,000-Mile Toyota Pickup with New Muffler and Tailpipe Fails NO PPM Test -- Any Idea as to Nature of Problem?

June 10, 2004 9:03 AM

My truck failed an emissions test for the first time (in No. Virginia). It's a 1993 Toyota pick-up, 2x4, 2.4L - 4cyl. (ext. cab). I just turned 200,000 miles on it last month and replaced the muffler and tailpipe the day before the inspection. The failure is with the NO ppm test. It failed at both 15 MPH and 25, but not by much. Am I looking at a converter problem for sure or is there something I can do first before replacing it? What's the best way to approch this problem?
posted by Witty to travel & transportation (5 comments total)

Used to be (in New Jersey) that there were two types of inspections: the first done by a state-run facility, and reinspections done by licensed service stations. If you failed, you brought your vehicle to a service station where it would be made right. My 72 bug would never ever pass emissions, so I would time the inspection before the next scheduled tune up, let it fail, take it to my mechanic who would tune it up and then "pass" it.
Things are probably more strict and more realistic now, but you never know...
posted by plinth at 9:14 AM on June 10, 2004

Chances are decent that the cat is fine, and you're running lean. If you didn't fail by much, this can probably be corrected inexpensively by either adjusting the base lambda a little richer. If the vehicle has no adjustment mechanism, a new oxygen sensor ought to do the trick.

Have you ever replaced it?
posted by trharlan at 12:02 PM on June 10, 2004

Forgive the grammar. You can email me if you're confused.
posted by trharlan at 12:03 PM on June 10, 2004

No, I've never changed it. I've hardly ever had to do anything to the sucker... new radiator, new dist. cap, and the aforementioned exhaust (a couple of times). I'm sure it could stand new plugs and wires, which I realize is probably totally unrelated, just sayin'... and I think I'll have someone hook me up with a new timing belt. But before doing any of that, I just wanted to make sure I wasn't getting ready pump a bunch of money into a vehicle that may be on it's way out. But it drives fine, starts up great, sounds pretty good... always has. It's paid for and deserves to be driven 'til it just can't drive no more. But this emissions failure is literally the first non-obvious thing to go wrong with this truck since day one. Everything else has just been standard maintenance/replacement type stuff.
posted by Witty at 7:37 PM on June 10, 2004

Well, you definitely ought to replace the oxygen sensor, then. You can do it yourself, pretty easy. Also, if you want to save some $$ on the replacement and you know how to solder (or have friends/family who do), you can save some money by buying a generic unit and soldering the old harness on to it. I've done it many, many times.
posted by trharlan at 9:52 AM on June 11, 2004