My 1991 5.2L v8 Dakota (216k miles) is in need of a current inspection sticker (lest I get another ticket for said offense). I bought the truck last summer for a song - and it's performed well for me..

The truck runs great (smooth) - no smoke, etc... however, it failed the emissions test run by 2 different shops.

HC (ppm) Standard is 137 - mine read 220 (failed)
CO(%) Std is 1.52 - mine read 3.06 (failed)
NO% (ppm) - Std is 859 - Mine is 116 (pass)

The above numbers were for the 25mph test.

My question... Would these numbers be consistent with a hi-flow aftermarket catalytic converter? I looked at the exhaust, and the converter that is there - is painted blue, and is only a little bit bigger than the exhaust pipe itself. It has on outflow port that goes back to the air pump - so if it's aftermarket part - it looks like it's hooked up correctly... Looks nothing like any other cat. converter that I've seen. (most I've seen look like a small muffler - and certainly aren't painted blue).

I **OCCASIONALLY** get a CEL, with codes 12, 41, 51, 55 -

41 = ( Charging system excess or lack of field current)
51 = ( Lean Condition )

I changed the spark plugs this week, (and ran some "emissions lowering snake-oil elixir" through the tank) - with no appreciable change in the emissions test... I replaced the O2 sensor a few months ago (again - no appreciable change in the occasional code 51 showing up -)

Ideas?

 

I was not aware that dallas county required the sniffer. I'm in mansfield (Tarrant Co) and no sniffer for me.

I can't help on the numbers, maybe somebody else that has to get sniffed can elaborate. But a Cat should be quite large, aftermarket or not. What you are describing sounds more like a glasspack muffler than a cat. But if the full muffler is there and this has the third outlet, it has to be a cat….but I'll go with the theory that it's a inefficient high-flow.

 

Dallas county was one of the first to have the emissions testing implemented.

Yes - the full muffler is there...

 

I'm not sure what to say. Hopefully somebody else will chime in. Mine is pretty much set up to race but I have all the stock emissions there (barely passes the OBDII test), I've never been sniffed.

 

Best I can say is run cleaner through like you did. Get hotter plugs. Get hotter thermostat. Run premium fuel. Clean air cleaner. Keep it hot for the test and hope for the best.

 

I'll move this post to the first gen Dakota forum.

 

obviously the vehicle was driven in a county where no emmission test was required.
yes- you will need new catalytic converter- the system is not able to handle the small high flow converter.
lot of people think, to install something like that will increase the power- but mostly the opposite is the case.
if you do so, you have to do a lot more than that. I guess your truck is also a gas hog.
the error codes you get are likely indicated by the O2 sensors who are at their limit due to the system.
The catalytic converter supposed to convert Nh, CO and HC in Co2, H2O and Nox. that's why your No is so low- should be higher and the rest gets lower automatically.
try to get the catalytic converters at the junk yard.
I would also check- just for safety- if other manipulations are done to the truck and fix it.
to get more HP out of an engine it takes way more than just installing a high flow catalytic converter and a flow master.

good luck.

Chris

 

It's a good idea to do an oil change, spark plugs, cap rotor and wires immediately before a smog test in a vehicle that old. You probably do need a better cat. EDIT the reasoning here is that used oil off gasses hydrocarbons a lot more than new oil and can make the difference in a test and I think the cleaner burning made possible by new cap rotor etc is obvious.

If that does not work I would ask the folks who test it what needs fixing as they should know since the machine sniffing it should be telling them what is running right and what isn't.

 

A new catalytic converter did the trick. $99 for the converter, plus about $150 labor for the weld job (including the metal line back to the air pump).

Passed the emissions test like a champ.

Next year, though - it's old enough to be exempt from emissions testing.

@Chris65 - I don't know the history of the truck... I bought it last year for a song ($800) - and it's run well for me - but yes - it's a gas hawg.

I also found a fuel line leak from the rubber hose at the inlet to the carburetor. The rubber lines need to be replaced BADLY (from the crimped fitting to the carb, as well as from the crimped fittings on either side of the fuel filter). I'll be replacing those fuel lines ASAFP.

Thanks all!!!

 

i figured i should chime in on this government B.S!! take your truck and get a bolt on converter,then you can go to a strait pipe after the emissions test is over with,hear in ohio i havent heard of an e check for a while now...in fact i dont think the world is getting warmer,i think its getting colder after the winter we just went through..lol..but,if your exempt next year,then your good..