Gnuman Posted March 31, 2005 Share Posted March 31, 2005 I got my emissions tested in order to register my car the other day, and I noticed that my hydrocarbons and CO were a lot higher at idle than at running speed (they test at idle and 2500RPM). I was wondering if a can of Seafoam would help this at all? I still passed with lots of room to spare, but I want even better emissions if I can get that. I also had my largest tank-fill today. with 358 miles on the trip meter, I took 15.150 gals for an MPG of 23 and change. I really do not want to get that close to 15.8 ( the tank size listed in the owner's manual) again, I must tell you. . . I drove most of the way home with the low fuel indicator on, because the gas is $.05 to $.10 cheaper per gal out here, compared to where I'm working right now. Would Seafoam improve milage any, if it cleaned up the top end? Or would that be an O2 sensor thing I need to look at? I know that my O2 readings were the same for running speed as for idle, so I dunno if the O2 sensor is bad ( or even bad enough to cause the fuel trim to be off). I'm thinking that perhaps a can of Seafoam might help those two things. Or am I selling myself snake oil? Quote Link to comment Share on other sites More sharing options...
Chef Posted March 31, 2005 Share Posted March 31, 2005 That's normal. Cars tend to produce higher concentrations of these pollutants at idle than at higher rpm. Probably somethig to do with less engine efficiency at those rpms and possibly due to the temperature of the cat (would be hotter at higher rpms due to increased exhaust heat, and therefore likely more efficient). I got my emissions tested in order to register my car the other day, and I noticed that my hydrocarbons and CO were a lot higher at idle than at running speed (they test at idle and 2500RPM). I was wondering if a can of Seafoam would help this at all? I still passed with lots of room to spare, but I want even better emissions if I can get that. I also had my largest tank-fill today. with 358 miles on the trip meter, I took 15.150 gals for an MPG of 23 and change. I really do not want to get that close to 15.8 ( the tank size listed in the owner's manual) again, I must tell you. . . I drove most of the way home with the low fuel indicator on, because the gas is $.05 to $.10 cheaper per gal out here, compared to where I'm working right now. Would Seafoam improve milage any, if it cleaned up the top end? Or would that be an O2 sensor thing I need to look at? I know that my O2 readings were the same for running speed as for idle, so I dunno if the O2 sensor is bad ( or even bad enough to cause the fuel trim to be off). I'm thinking that perhaps a can of Seafoam might help those two things. Or am I selling myself snake oil? Quote Link to comment Share on other sites More sharing options...
charlierh2 Posted March 31, 2005 Share Posted March 31, 2005 doesnt your a/f ratio get more lean all the way up to wot? Quote Link to comment Share on other sites More sharing options...
Gnuman Posted March 31, 2005 Author Share Posted March 31, 2005 That's normal. Cars tend to produce higher concentrations of these pollutants at idle than at higher rpm. Probably somethig to do with less engine efficiency at those rpms and possibly due to the temperature of the cat (would be hotter at higher rpms due to increased exhaust heat, and therefore likely more efficient). I know it is normal for the idle emissions to be higher, but my car differs more than the "average" they quote. I'm wanting to bring that down is all. Wouldn't the cat be at a similar temp, considering that the car was already warmed up? I can't see it fluxuating that much. . The numbers I got were: Idle: 44PPM HC (average 29, limit 120) 0.28% CO (average 0.10, limit 1.0) driving speed: 6PPM HC (average 20, limit 140) 0.10% CO (average 0.10, limit 1.0) The CO2 was 14.9% at idle and 15.1% running. The O2 was .1% both places. Yes, I passed. Yes I still have room to spare. Yes I still want to bring my idle numbers down a bit. The question is will Seafoam help at all? If not, what will (besides a new engine, which I'm nowhere near close to needing)? Quote Link to comment Share on other sites More sharing options...
friendly_jacek Posted March 31, 2005 Share Posted March 31, 2005 I dont see how seafoam could help. But it may not hurt either. It looks like your emission components are working. I also get middling mpg in 00 legacy and "heavy" exhaust smell on cold engine. The only irregularity I found was excessive fuel pressure. Waiting for the part to be delivered. It that is the issue in my car (i hope), maybe there are more subs with defective fuel pressure regulators. Quote Link to comment Share on other sites More sharing options...
edrach Posted March 31, 2005 Share Posted March 31, 2005 Old saying: "Don't try to fix what's not broke." It would be nice to have it better, but your engine is working just fine. Seafoam probably wouldn't hurt you, but any dinking with the system might make things worse. I know it is normal for the idle emissions to be higher, but my car differs more than the "average" they quote. I'm wanting to bring that down is all. Wouldn't the cat be at a similar temp, considering that the car was already warmed up? I can't see it fluxuating that much. . The numbers I got were: Idle: 44PPM HC (average 29, limit 120) 0.28% CO (average 0.10, limit 1.0) driving speed: 6PPM HC (average 20, limit 140) 0.10% CO (average 0.10, limit 1.0) The CO2 was 14.9% at idle and 15.1% running. The O2 was .1% both places. Yes, I passed. Yes I still have room to spare. Yes I still want to bring my idle numbers down a bit. The question is will Seafoam help at all? If not, what will (besides a new engine, which I'm nowhere near close to needing)? Quote Link to comment Share on other sites More sharing options...
Scoobaroo Posted March 31, 2005 Share Posted March 31, 2005 How old is your o2 sensor? They can get lazy without setting a code. For them to set a code, they have to be really bad. (unresponsive, flatline, etc.) Quote Link to comment Share on other sites More sharing options...
Gnuman Posted March 31, 2005 Author Share Posted March 31, 2005 How old is your o2 sensor? They can get lazy without setting a code. For them to set a code, they have to be really bad. (unresponsive, flatline, etc.) The car has 152000 miles on it. I seriously doubt that the O2 sensor has ever been changed. When I hit 180000 I plan on a refit (new t-belt, all new seals, new waterpump, torque the oilpump screws and reseal it, new O2 sensor, flush coolant, new clutch, etc). This car has had basic maint since the day it was bought new (by a friend), and then by my stepdaughter, who gave it to me when it started getting expensive for her to have fixed. I'm not even sure that the T-belt was changed at 105K. The only reason I'm waiting until 180K is to get all the parts I want to change at a rate I can afford (I'm stockpiling the parts). The engine is non-interferance, so I feel safe in pushing it that far, but not much farther. Quote Link to comment Share on other sites More sharing options...
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