1990 Dodge Spirit 3.0 V-6 Emission Test Failure

[Tom Schwartzmier]

I am having difficulty passing my state mandated emission test on a 1990 Dodge Spirit with a 3.0 V-6 engine. I recently acquired this vehicle which has only 32K original miles on it. It was brought in from out of state where it had not been required to be tested for emissions.

The vehicle has obviously not been driven much but I have driven it for over 500 miles so the gasoline in it was fresh. The station that performed the emission testing suggested a tune up which I am in the process of doing before I bring it back for a re-test. About all that can be replaced during a tune up is plugs, dist. cap, rotor and plug wires. I am also running gum-out fuel injector cleaner through it and then a product from CRC which guarantees that you will pass the emission test or they'll refund double what you paid for it.

I can't help but wonder if there isn't something else that I should to correct this problem once and for all since it will have to re-tested annually and with such low mileage I might have this vehicle for several years.

Any suggestions would be appreciated.

 

[Matthew S. Whiting]

I am having difficulty passing my state mandated emission test on a 1990 Dodge Spirit with a 3.0 V-6 engine. I recently acquired this vehicle which has only 32K original miles on it. It was brought in from out of state where it had not been required to be tested for emissions.

The vehicle has obviously not been driven much but I have driven it for over 500 miles so the gasoline in it was fresh. The station that performed the emission testing suggested a tune up which I am in the process of doing before I bring it back for a re-test. About all that can be replaced during a tune up is plugs, dist. cap, rotor and plug wires. I am also running gum-out fuel injector cleaner through it and then a product from CRC which guarantees that you will pass the emission test or they'll refund double what you paid for it.

What didn't pass? HC? NOx?

In addition to what you mention above, I'd change the air filter and check the EGR valve. Could be the catalytic convertor is dead also. Knowing what failed will help isolate the problem. Different pollution control devices serve different functions. For example, EGR helps to knock off the high temperature spikes during combustion which reduces formation of oxides of nitrogen. High HC could be fuel injector problems, clogged air filter, faulty mass air flow sensor, water temp sensor, etc.

I can't help but wonder if there isn't something else that I should to correct this problem once and for all since it will have to re-tested annually and with such low mileage I might have this vehicle for several years.

There's lots of other things to check, but the more information as to what the failure mode was, the less random parts replacement you will have to do.

Have you checked for fault codes? I'm not sure about the 3.0 engine, but my Acclaim with the 2.5L could be checked by cycling the ignition key as follows: on-off-on-off-on within something like a 5 second window and then counting the flashes on the check engine light. A long pause is a separator between digits and a short pause is a separator between pulses in a digit count. If memory serves, you should start with 12 and end with 55 and any real fault codes will be in between.

Matt

 

[Tom Schwartzmier]

Matt --

Thanks for your input and help. I've enclosed some additional information below.

Tom

What didn't pass? HC? NOx?

It failed on both. The CO% was 9.44 and the limit is 1.20 -- the HC ppm was 638 and the limit is 220. Both or these readings were at an idle.

It also failed both at 2,500 rpm test with readings of 8.59% and 281 ppm respectively. These are somewhat better but still not very close.

In addition to what you mention above, I'd change the air filter and check the EGR valve. Could be the catalytic convertor is dead also. Knowing what failed will help isolate the problem. Different pollution control devices serve different functions. For example, EGR helps to knock off the high temperature spikes during combustion which reduces formation of oxides of nitrogen. High HC could be fuel injector problems, clogged air filter, faulty mass air flow sensor, water temp sensor, etc.

The air filter was brand new. I'll have to check the EGR -- that's a good idea. I guess it could be catalytic converter. I am trying to run cleaner through the injectors -- it runs so smooth and well it's tough to imagine them being clogged.

One thing I have noticed about the vehicle is that the water temperature gauge never goes up very far -- it barely evers goes into the low end of the operating range -- this is much lower than a previous Spirit I owned and the Jeep that I have now. Maybe the thermostat is too low or not closing tightly to allow the temperature to rise. You wouldn't happen to know what temperature this should be would you ? Probably either 180 or 195 would be my guess.

There's lots of other things to check, but the more information as to what the failure mode was, the less random parts replacement you will have to do.

Have you checked for fault codes? I'm not sure about the 3.0 engine, but my Acclaim with the 2.5L could be checked by cycling the ignition key as follows: on-off-on-off-on within something like a 5 second window and then counting the flashes on the check engine light. A long pause is a separator between digits and a short pause is a separator between pulses in a digit count. If memory serves, you should start with 12 and end with 55 and any real fault codes will be in between.

I used to own an 1989 Spirit with a 2.5L turbo. I remember the trick with the codes. I'll have to give that a try -- I had forgot about this "trick"

 

[Matthew S. Whiting]

Matt --

Thanks for your input and help. I've enclosed some additional information below.

Tom

It failed on both. The CO% was 9.44 and the limit is 1.20 -- the HC ppm was 638 and the limit is 220. Both or these readings were at an idle.

OK, CO isn't the same as NOx. I forgot to mention CO in my first post. NOx shouldn't fail at idle anyway.

It also failed both at 2,500 rpm test with readings of 8.59% and 281 ppm respectively. These are somewhat better but still not very close.

The air filter was brand new. I'll have to check the EGR -- that's a good idea. I guess it could be catalytic converter. I am trying to run cleaner through the injectors -- it runs so smooth and well it's tough to imagine them being clogged.

I'll add the oxygen sensor to the list of items above. Basically, it sounds like you are running too rich given the high HC level. Any sensor that provides mixture control input to the ECM is suspect.

One thing I have noticed about the vehicle is that the water temperature gauge never goes up very far -- it barely evers goes into the low end of the operating range -- this is much lower than a previous Spirit I owned and the Jeep that I have now. Maybe the thermostat is too low or not closing tightly to allow the temperature to rise. You wouldn't happen to know what temperature this should be would you ? Probably either 180 or 195 would be my guess.

Could be a thermostat problem. Cool running could cause the problem you are seeing. I had the water temperature sensor fail on my Chevy truck a couple of years ago. The engine still warmed up fine, but the computer thought it was still cold. It ran it very rich which did wonders for power output, but gas mileage dropped by 40% and the exhaust pipe was black as could be. How does your tail pipe look?

Matt

 

[Tom Schwartzmier]

Matt --

Thanks again for your help.

The codes I got from rotating the key three times were 12 - 51 - 55. Code 51 is related to the oxygen sensor. I don't believe the other codes pertain to a problem.

See additional information below.

Tom

OK, CO isn't the same as NOx. I forgot to mention CO in my first post. NOx shouldn't fail at idle anyway.

NOx was not on the print out they gave me -- just CO and HC

I'll add the oxygen sensor to the list of items above. Basically, it sounds like you are running too rich given the high HC level. Any sensor that provides mixture control input to the ECM is suspect.

Since I got the error code 51 I think the oxgen sensor is one of the the first things that I'll replace.

Could be a thermostat problem. Cool running could cause the problem you are seeing. I had the water temperature sensor fail on my Chevy truck a couple of years ago. The engine still warmed up fine, but the computer thought it was still cold. It ran it very rich which did wonders for power output, but gas mileage dropped by 40% and the exhaust pipe was black as could be. How does your tail pipe look?

The thermostat is a cheap precaution and it's easy to get to so I plan on changing it for sure. I have no unusual black deposits on the exhaust pipe.

 

[Daniel J. Stern]

I'll add the oxygen sensor to the list of items above. Basically, it sounds like you are running too rich given the high HC level. Any sensor that provides mixture control input to the ECM is suspect.

Replacing sensors and other parts willy-nilly isn't the way to fix the problem. Proper diagnosis (starting with a readout of the fault codes) is.

How does your tail pipe look?

Except in cases of *extremely* rich running, tailpipe appearance is not a reliable indicator of combustion conditions in any car burning unleaded gasoline, with or without a catalytic converter.

DS

 

[Matthew S. Whiting]

Replacing sensors and other parts willy-nilly isn't the way to fix the problem. Proper diagnosis (starting with a readout of the fault codes) is.

I agree and said much the same thing earlier in the thread if you'd bothered to read it.

Except in cases of *extremely* rich running, tailpipe appearance is not a reliable indicator of combustion conditions in any car burning unleaded gasoline, with or without a catalytic converter.

Well, when my water temp sensor failed on my pickup, it was running extremely rich. I went from 17 MPG to 12 MPG.

Matt

 

[Kirk Matheson]

Usually, a stuck open thermostat will cause a "17" to be set.

-Kirk Matheson