Failed emission test

[87MJTIM]

Well, after 25 years, the truck has failed the MD emissions test. Once every two years, MD requires an emissions test for all vehicles in certain counties. Every previous test it has passed with flying colors, but not yesterday. It failed two tests - hydrocarbon and carbon monoxide tests.

 

The liturature lists some likely causes. The first cause for both tests is "air to fuel mixture too rich." Which leads to my issues/questions.

 

About two years ago - after the previous test - I replaced the distributor. (I was replacing the cap and one of the screws broke inside the distributor. After failed attempts to remove the old screw, I just purchased a replacement distributor.) Ever since then, the truck does not have the same pick up (HA-HA) it used to have. It starts fine, it runs fine. However, it just doesn't have the excelleration it used to have, either starting out or on the highway. For example, on highways I have to shift down to 4th to maintain my speed on even modest hills.

 

I was careful line up the rotor when I installed the replacement. It only seemed to fit in one location.

 

Is it possible that I didn't line it up right? Can I adjust the timing? My Chiltons and Haynes indicated that I cannot adjust the timing.

 

Or are my issues elsewhere on the truck?

[Jeep Driver]

I would start with the 02 sensor.

[SubSonic]

There is no adjustment on the dizzy. If you put it in and it starts up and runs O.K. then it's been installed correctly. Make sure all plug connections are good. If this is all good, it is possible your parts store distributor has issues.

 

There is also a chance that at the same period of time something totally unrelated happened. Something like a catalytic converter that is beginning to clog will cause you to lose performance and fail emissions. This is just a thought.

 

You could also unhook your positive battery terminal and ground it to discharge any amount of voltage, this will allow the computer to reset and essentially relearn. While I don't know why a distributor would cause a need for this, it never hurts after replacing any component.

[Harley]

Or do what I did and register it as a collector which makes it emissions exempt. Here in NV anyway, not sure if its the same for you.

It cost me I think something like $45ish for the plates and $10/year for renewal and I don't have to deal with the smog crap.

[87MJTIM]

Or do what I did and register it as a collector which makes it emissions exempt. Here in NV anyway, not sure if its the same for you.

It cost me I think something like $45ish for the plates and $10/year for renewal and I don't have to deal with the smog crap.

 

MD has historic plates for vehicle that are 20 yrs+ old. So, that is an option. But I believe there are restrictions on driving it - ie. maximum miles per yr, holidays and weekends. I will look into it. This is a daily driver.

[Harley]

Yeah thats the catch. It might not work for ya. Was a thought though. Only restriction here is 5000/yr

[87MJTIM]

There is no adjustment on the dizzy. If you put it in and it starts up and runs O.K. then it's been installed correctly. Make sure all plug connections are good. If this is all good, it is possible your parts store distributor has issues.

 

There is also a chance that at the same period of time something totally unrelated happened. Something like a catalytic converter that is beginning to clog will cause you to lose performance and fail emissions. This is just a thought.

 

You could also unhook your positive battery terminal and ground it to discharge any amount of voltage, this will allow the computer to reset and essentially relearn. While I don't know why a distributor would cause a need for this, it never hurts after replacing any component.

 

I replace the catalytic converter two years ago. It clogged up and just about killed the engine. I limped it home...just barely.

 

I will switch the o2 sensor, and new plugs and wires.

 

This may be completely unrelated, but last summer, on a 100+ degree day, I was stopped at a light for a long time with the engine temp rising. Eventually pulled into a parking spot. Shot off the truck. Got out. When I closed the door, I heard a "pop" noise. Looked under the truck and saw the coolant pouring onto the ground from the res. bottle. The screw cap popped off. It would not screw back on.

 

I called my mechanic for help. He told me I could have a leaking head gasket. This could cause back pressure in the cooling system that caused the cap to pop off.

 

I got a new res bottle and cap. Replaced just the cap and have not had that problem since.

 

However, could a back cylinder be the issue?

[SubSonic]

I, as well as you I'm sure, would like to think if the overheating issue has not resurfaced and your not dumping any white smoke that that isn't probable, but I suppose it couldn't be ruled out entirely. However, if neither of these are occuring, I doubt that it's related to the emissions.

 

I installed a new cat on mine six months ago, and just squeeked by emissions, even with a new h.o. motor. With my old OEM cat, it wasn't even close, passed with flying colors. I feel that some cheap replacement cats really do have barely enough material to get you by. Of course they all have mandated warranties so replacement is free if you can prove that to be the issue. I also feel it may have something with my extremely free flowing exhaust... ie. cat and straight pipe out, meaning the exhaust spends far less time being catalyzed.

 

As the previous post said an o2 sensor couldn't hurt, and if you dare try any snake oil, I've had decent luck with seafoam... if you like smoke shows, that is.

 

Check anything that may have been bumped during installation of the new dizzy, low fuel pressure or a tps might cause the sluggish symptoms. All this can be simply checked, but I'd do my best not to throw parts at it. Unless you just want to throw stuff at it until you reach the money cap and they have to pass you... :dunno: but that's time poorly spent and a problem undiagnosed if it doesn't fix it.