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Greetings esteemed board, I seek your consensus on the following issue :
Presented for your review is a recently purchased '94 Aero 5spd with 150,000 miles. The car had previously been in Idaho, so emissions were have not been tested on the car since at least 2004.
I took the car to be inspected, and it failed Utah emissions because of high NOx readings. HC's and C0 were both well within limits. Utah puts the car on a dyno and does a test at 15mph and 25 mph. At 15mph, it had a reading of ~1250 with the legal limit being 1100. At 25 mph, the legal limit is lower at 950, while the car generated ~1180 ppm.
In addition, the car seems to have somewhat less power than I expect. It's still fairly quick, but it just doesn't have the same giddyap as my '92 (also a 5spd), and although the older car does have a performance chip in it, the Aero should still have more horses. It's also a bit difficult to get started in the morning. No matter what the outside temp, my '92 fires right up and in short order settles into a steady idle. The Aero, however, needs you to give it some gas and run the engine at ~1500 rpm or so at least, else it will sputter and stall. Once warmed up, though, it runs smoothly.
I've done the obvious things : swapped the DI for one of the spares I keep handy (thankfully, my '92 9k and the '97 900 SE all use the same DI). I also checked for vacuum leaks and didn't really find any (there's a lot fewer hoses on this year than on my other 9k's). The car has brand new spec plugs, clean oil, air filter, and all. I also cleaned the air intake temp sensor. Oh yeah, the CEL is not on.
As far as I can tell, there are 2 basic potential problems (that aren't necessarily exclusive) :
1. bad catalytic converter
2. engine is running lean
Is there any way to determine, other than process of elimination that you have a bad cat? Would a bad cat hurt performance in the way that I'm seeing?
As far as diagnosing a lean condition, I've not yet looked at the plugs to see what color they are, but I will. I've read in the archives that you can test the air intake sensor with a multimeter, but I can't find the specs for it. Is there a similar way to test the MAP sensor?
I do have an ISAT, with cables and such, but I haven't had a lot of luck with it. I occasionaly can read codes (P202020, P000000), but a most of the time I get "No Connection". If anyone knows where I can find documentation on how to use this little gem, I'd greatly appreciate it.
posted by 151.151.21...
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