Well, it's that time again - time to have the old chariot smog tested.
3800 1994 TransSport had new engine and cat installed just over 2
years ago. It now has less than 30,000Km on it. When the new engine
was put in it just squeaked by on the Hydrocarbons at speed, and was
good at idle. I figured it would get better when the engine was broken
in. Today it failed the HC. NOX is on the high side, but still well
within range. Idle test is fine. CO is about half the limit. I
suspect the beast is running lean (it does act a bit that way - feels
a bit weak at light throttle 80-100km cruise, but pulls strongly when
operating at higher throttle setting)
Any experience with smogging this engine that might point me to the
On the ASM2525 HC ppm limit is 50, read 89.
co% limit is 0.28, read 0.17
NO ppm limit is 696, read 571
RPM was 1647 and dilution was 14.3
On the curb idle test, HC ppm limit is 200, read 80,
co% limit is 1.0, read 0.08
Idle RPM was 715, with dilution at 13.7
The engine has less than 35000km on it, with a new Cat at the time of
installation. Prior to Jan 1 the limits were higher - and when the
engine was installed the HC was just about at the limit.I suspect the
readings are now exactly the same as they were on the first test -
I just dug out the original test results from August 2002 -
ASM2525 HC limit was 67, and read 65.
CO% limit was .37 and read .11
NO ppm limit was 930, and read 608
Curb idle HC ppm limit was 200 and read 54
Idle co% limit was 1.00 and read .04
This means the vehicle would not have passed with a brand new engine
and Cat converter - with new EGR, cleaned injectors, new plugs, and
the whole nine yards.
The original .65 HC was 15 over today's limit.
It's really a shame that they don't give you gas measurements for
-all- the gasses, then I could plug them into a lambda calculator
and we'd better know where the mixture was.
NOx is highest when the mix is slightly richer from
stoichiometric, HC will creep higher when rich also, you already
suspect that the CO is a bit high.
IIRC, you have a scan tool, so I'd check the fuel trim numbers
and clean the MAF sensor and verify that the EGR is in fact
opening as it should.
Sounds like whatever condition is causing the fail is something
that existed before the engine work. A properly rebuilt engine
should run clean from the get-go.
If the cat-con is an aftermarket unit, it is still suspect even
though it is relatively new, most aftermarket convertors are only
30-40 percent efficient right out of the box.
We've pretty much given up on the aftermarket ones here in
Wisconsin because of this..
Car Sound convertors have a good reputation for higher efficiency
and there is a company in Alabama called "Browns" that sells
rebuilt OEM convertors for close to what the aftermarket ones
sell for and lastly, picking a convertor from the Walker catalog
according to shell and pipe size instead of by application can
result in major reductions because of the larger catalyst bed
Well, it appears to be the cat -scan tool shows everything as it
should be, and the cat is NOT lighting under normal test conditions.
I've ordered a direct fit cat from UAP for $195 Canadian - a whole lat
better than $1100 from the dealer!!! - and I'm NOT going to fart
around with a universal, when a CHEAP one is $95.
With any luck it will pas on Tuesday.
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