Help request - NOx doubled in dyno inspection

Hi,

This is the same situation I had the last time I went for
inspection... Nox on my 91 BMW 318i failed. Only this time, it has
doubled from the accepted level! My car an E30 318i with the M42 1.8L
engine was designed without an EGR or any other sort of NOx control,
except, i suppose for the catalyst in the cat converter.

Background:
For reference, in 2003, my emissions (dyno test) were as follows:
NOx 1114 (standard is 1134)
HC 97 (standard is 146)
CO% 0.33 (standard is 0.82)
CO2% 14.1
O2% 0.2

Failure in 2005:
NOx 1167
HC 96
CO% 0.35
CO2% 15.3
O2% 0.3

Replaced cat converter, reading that passed in 2005:
NOx 1074
HC 133
CO% 0.34
CO% 14.8
O% 0.2

My failure today:
NOx: 2126 (DOUBLED!!!!)
HC:161
CO%:0.54
CO2%:14.1

As a reference, my 98 Chevy truck (owned since new) had these results
on its last dyno test (currently exempted because its an OBDII
vehicle, so these are a little old, but done on the same system):
NOx 16
HC 7
CO% 0.01
CO2% 15.2
O2% 0

Spark plugs are very clean and correctly gapped, etc., I even ran the
new Amsoil PI through the tank just before to ensure that CCs, etc.
were cleaned out. No dice.

I do have a dinan chip, Ill be removing it as of right now, to
hopefully be able to pass... The car runs great and gets me good fuel
economy, Id hate to have to spend $500 on senseless repairs to get a
waiver, just because this car never came with an EGR from the factory
(by design).

UGH!

Any thoughts or comments would be most appreciated. I have heard that
ingnition coils (this car has a distributorless system) going bad can
cause funny problems like this. Any thoughts???

Thanks,

JMH

Nox is a direct function of cylinder temps, this is affected by timing,
engine temps, fuel mixture, compression ratio, and of course the cat is
the final clean up component. A older high mileage vehicle could always
be at risk for this issue, try retarding the timing slightly, maybe run
carbon cleaner thru the intake, no magic bullet here.


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JMH wrote:
> Hi,
>
> This is the same situation I had the last time I went for
> inspection... Nox on my 91 BMW 318i failed. Only this time, it has
> doubled from the accepted level! My car an E30 318i with the M42 1.8L
> engine was designed without an EGR or any other sort of NOx control,
> except, i suppose for the catalyst in the cat converter.
>
> Background:
> For reference, in 2003, my emissions (dyno test) were as follows:
> NOx 1114 (standard is 1134)
> HC 97 (standard is 146)
> CO% 0.33 (standard is 0.82)
> CO2% 14.1
> O2% 0.2
>
> Failure in 2005:
> NOx 1167
> HC 96
> CO% 0.35
> CO2% 15.3
> O2% 0.3
>
> Replaced cat converter, reading that passed in 2005:
> NOx 1074
> HC 133
> CO% 0.34
> CO% 14.8
> O% 0.2
>
> My failure today:
> NOx: 2126 (DOUBLED!!!!)
> HC:161
> CO%:0.54
> CO2%:14.1
>
> As a reference, my 98 Chevy truck (owned since new) had these results
> on its last dyno test (currently exempted because its an OBDII
> vehicle, so these are a little old, but done on the same system):
> NOx 16
> HC 7
> CO% 0.01
> CO2% 15.2
> O2% 0
>
> Spark plugs are very clean and correctly gapped, etc., I even ran the
> new Amsoil PI through the tank just before to ensure that CCs, etc.
> were cleaned out. No dice.
>
> I do have a dinan chip, Ill be removing it as of right now, to
> hopefully be able to pass... The car runs great and gets me good fuel
> economy, Id hate to have to spend $500 on senseless repairs to get a
> waiver, just because this car never came with an EGR from the factory
> (by design).
>
> UGH!
>
> Any thoughts or comments would be most appreciated. I have heard that
> ingnition coils (this car has a distributorless system) going bad can
> cause funny problems like this. Any thoughts???
>
> Thanks,
>
> JMH
>
Was the replacement cat an oem unit or aftermarket?

On Jun 7, 9:09 pm, Steve Austin > wrote:
> JMH wrote:
> > Hi,
>
> > This is the same situation I had the last time I went for
> > inspection... Nox on my 91 BMW 318i failed. Only this time, it has
> > doubled from the accepted level! My car an E30 318i with the M42 1.8L
> > engine was designed without an EGR or any other sort of NOx control,
> > except, i suppose for the catalyst in the cat converter.
>
> > Background:
> > For reference, in 2003, my emissions (dyno test) were as follows:
> > NOx 1114 (standard is 1134)
> > HC 97 (standard is 146)
> > CO% 0.33 (standard is 0.82)
> > CO2% 14.1
> > O2% 0.2
>
> > Failure in 2005:
> > NOx 1167
> > HC 96
> > CO% 0.35
> > CO2% 15.3
> > O2% 0.3
>
> > Replaced cat converter, reading that passed in 2005:
> > NOx 1074
> > HC 133
> > CO% 0.34
> > CO% 14.8
> > O% 0.2
>
> > My failure today:
> > NOx: 2126 (DOUBLED!!!!)
> > HC:161
> > CO%:0.54
> > CO2%:14.1
>
> > As a reference, my 98 Chevy truck (owned since new) had these results
> > on its last dyno test (currently exempted because its an OBDII
> > vehicle, so these are a little old, but done on the same system):
> > NOx 16
> > HC 7
> > CO% 0.01
> > CO2% 15.2
> > O2% 0
>
> > Spark plugs are very clean and correctly gapped, etc., I even ran the
> > new Amsoil PI through the tank just before to ensure that CCs, etc.
> > were cleaned out. No dice.
>
> > I do have a dinan chip, Ill be removing it as of right now, to
> > hopefully be able to pass... The car runs great and gets me good fuel
> > economy, Id hate to have to spend $500 on senseless repairs to get a
> > waiver, just because this car never came with an EGR from the factory
> > (by design).
>
> > UGH!
>
> > Any thoughts or comments would be most appreciated. I have heard that
> > ingnition coils (this car has a distributorless system) going bad can
> > cause funny problems like this. Any thoughts???
>
> > Thanks,
>
> > JMH
>
> Was the replacement cat an oem unit or aftermarket?

It was an aftermarket, no name no less...

If needs be, Ill need to spend some $$$ to get my emissions waiver
($450 must be spent). I hate throwing parts at perfectly operating
cars, but if that is what must be done, then Ill likely obtain a DEC
(unless someone suggests another brand or to go OE only) cat setup for
my car (the aftermarket was simply cut and welded in), as Im sure a
$250 cat converter is not of the highest quality.

Thanks!

JMH

JMH wrote:
> On Jun 7, 9:09 pm, Steve Austin > wrote:
>> JMH wrote:
>>> Hi,
>>> This is the same situation I had the last time I went for
>>> inspection... Nox on my 91 BMW 318i failed. Only this time, it has
>>> doubled from the accepted level! My car an E30 318i with the M42 1.8L
>>> engine was designed without an EGR or any other sort of NOx control,
>>> except, i suppose for the catalyst in the cat converter.
>>> Background:
>>> For reference, in 2003, my emissions (dyno test) were as follows:
>>> NOx 1114 (standard is 1134)
>>> HC 97 (standard is 146)
>>> CO% 0.33 (standard is 0.82)
>>> CO2% 14.1
>>> O2% 0.2
>>> Failure in 2005:
>>> NOx 1167
>>> HC 96
>>> CO% 0.35
>>> CO2% 15.3
>>> O2% 0.3
>>> Replaced cat converter, reading that passed in 2005:
>>> NOx 1074
>>> HC 133
>>> CO% 0.34
>>> CO% 14.8
>>> O% 0.2
>>> My failure today:
>>> NOx: 2126 (DOUBLED!!!!)
>>> HC:161
>>> CO%:0.54
>>> CO2%:14.1
>>> As a reference, my 98 Chevy truck (owned since new) had these results
>>> on its last dyno test (currently exempted because its an OBDII
>>> vehicle, so these are a little old, but done on the same system):
>>> NOx 16
>>> HC 7
>>> CO% 0.01
>>> CO2% 15.2
>>> O2% 0
>>> Spark plugs are very clean and correctly gapped, etc., I even ran the
>>> new Amsoil PI through the tank just before to ensure that CCs, etc.
>>> were cleaned out. No dice.
>>> I do have a dinan chip, Ill be removing it as of right now, to
>>> hopefully be able to pass... The car runs great and gets me good fuel
>>> economy, Id hate to have to spend $500 on senseless repairs to get a
>>> waiver, just because this car never came with an EGR from the factory
>>> (by design).
>>> UGH!
>>> Any thoughts or comments would be most appreciated. I have heard that
>>> ingnition coils (this car has a distributorless system) going bad can
>>> cause funny problems like this. Any thoughts???
>>> Thanks,
>>> JMH
>> Was the replacement cat an oem unit or aftermarket?
>
> It was an aftermarket, no name no less...
>
> If needs be, Ill need to spend some $$$ to get my emissions waiver
> ($450 must be spent). I hate throwing parts at perfectly operating
> cars, but if that is what must be done, then Ill likely obtain a DEC
> (unless someone suggests another brand or to go OE only) cat setup for
> my car (the aftermarket was simply cut and welded in), as Im sure a
> $250 cat converter is not of the highest quality.
>
> Thanks!
>
> JMH
>
When did the chip go in?