JHZR2
Staff member
Hi,
Last time I took my car (91 318i with M42 engine, 5sp manual trans) for inspection (6/2003), it just barely passed.
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
So I just slipped by. That test was done with an ProFormance chip installed, M1 15w-50 oil, Amoco low-sulfur premium fuel, and shortly after a tuneup and replacement of the breather hose sets.
Since then, in interest of lowering NOx, I replaced my O2 sensor with an OE bosch. Additionally, thinking that the proformance chip had something to do with it, I bought a Dinan chip for the car, and installed it - thinking this was a name brand that may be designed a little better than my EBAY chip.
The car has been running well. Very smooth, good MPG (29 average), decent power. No signs of an issue, and no CELs or codes. Ive been running on top-tier conoco gasoline currently, with regular use of FP (did a shock dose not too long ago) and LC.
Today I took the car in. My readings were as follows:
NOx 1167
HC 96
CO% 0.35
CO2% 15.3
O2% 0.3
Both tests were performed after a good (15+ mile highway drive) warmup, fast idling while sitting (~2000 RPM), etc.
So my NOx went up just enough to fail me. HC was essentially the same, CO was more or less the same but increased slightly, CO2 increased quite a bit, and O2 increased a tiny bit too.
What do you think? All breather hoses are fine, there is no indication of any leaks of any sort anywhere. Maybe there is a leak on the exhaust after the engine, but I havent seen any evidence of it - usually things like that can be heard fairly easily.
Would use of a chip like the dinan one that Im using cause things like this? If spark/injection timing (thats what chips adjust, right?) is altered, would this cause the potential for hotter combustion and thus higher NOx? The engine doesnt have a knock sensor, so 91+ is mandatory; I always use 93.
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
Based upon the results of the newer, lower mileage vehicle, it tells me that my BMW is:
a) not oxidizing all the CO as it should, as O% ought to be 0
b) CO2 is as high in the BMW case as in the case of my truck, with the BMW having less CO oxidized, and higher HC content. This would tell me that the BMW is running richer than the truck is, and that the cat isnt doing its conversion as it ought to.
Any ideas / suggestions? I NEED to get passed by tomorrow, as I need the car and will be down in DC for the next 4 months.
Thanks in advance for any advice.
Last time I took my car (91 318i with M42 engine, 5sp manual trans) for inspection (6/2003), it just barely passed.
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
So I just slipped by. That test was done with an ProFormance chip installed, M1 15w-50 oil, Amoco low-sulfur premium fuel, and shortly after a tuneup and replacement of the breather hose sets.
Since then, in interest of lowering NOx, I replaced my O2 sensor with an OE bosch. Additionally, thinking that the proformance chip had something to do with it, I bought a Dinan chip for the car, and installed it - thinking this was a name brand that may be designed a little better than my EBAY chip.
The car has been running well. Very smooth, good MPG (29 average), decent power. No signs of an issue, and no CELs or codes. Ive been running on top-tier conoco gasoline currently, with regular use of FP (did a shock dose not too long ago) and LC.
Today I took the car in. My readings were as follows:
NOx 1167
HC 96
CO% 0.35
CO2% 15.3
O2% 0.3
Both tests were performed after a good (15+ mile highway drive) warmup, fast idling while sitting (~2000 RPM), etc.
So my NOx went up just enough to fail me. HC was essentially the same, CO was more or less the same but increased slightly, CO2 increased quite a bit, and O2 increased a tiny bit too.
What do you think? All breather hoses are fine, there is no indication of any leaks of any sort anywhere. Maybe there is a leak on the exhaust after the engine, but I havent seen any evidence of it - usually things like that can be heard fairly easily.
Would use of a chip like the dinan one that Im using cause things like this? If spark/injection timing (thats what chips adjust, right?) is altered, would this cause the potential for hotter combustion and thus higher NOx? The engine doesnt have a knock sensor, so 91+ is mandatory; I always use 93.
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
Based upon the results of the newer, lower mileage vehicle, it tells me that my BMW is:
a) not oxidizing all the CO as it should, as O% ought to be 0
b) CO2 is as high in the BMW case as in the case of my truck, with the BMW having less CO oxidized, and higher HC content. This would tell me that the BMW is running richer than the truck is, and that the cat isnt doing its conversion as it ought to.
Any ideas / suggestions? I NEED to get passed by tomorrow, as I need the car and will be down in DC for the next 4 months.
Thanks in advance for any advice.