Emissions

[java]

so i went to get my emissions test done. the last one i will ever need might i add. and i just barely fail CO at idle....
anyone a emissions expert?
so its a 22RE out of a 87 runner, hedman header, 2.5" exhaust, no cat.

my idle is set high, about 1100 rpms, if i hold the steering at lock to add a little load to the engine it is within the test range.

the only thing i could think of is do have a small exhaust leak at the header gasket, could this affect it? didnt even cross my mind till i failed.

the only parts counted are HC and CO, i failed the idle CO

Test Results:
Cruise: HC CO CO+CO2 02
allowable 150 1 6 NA
tested 95 .08 14.48 1.37

allowable 220 1.2 6 NA
Idle 126 1.65 15.95 .34

thanks for any help. :beer:

 

[Trainwreckinseattle]

Elevated hydrocarbon (HC) emissions usually indicate ignition misfire due to fouled spark plugs or a bad plug. But high HC emissions can also be caused by burned exhaust valves (check compression), lean misfire (check for vacuum leaks, low fuel pressure or dirty injectors), or rich fuel conditions (fuel saturated carburetor floats, excessive fuel pressure, leaky injectors or a dead O2 sensor).

High carbon monoxide (CO) emissions are a telltale sign of a rich fuel mixture. On older carbureted vehicles, fuel-saturated plastic floats, incorrect float settings, leaky power valves and misadjusted chokes are often responsible for the rich mixture. On newer vehicles with feedback fuel controls and fuel injection, leaky injectors, excessive fuel pressure and sluggish or contaminated O2 sensors are all possibilities to investigate.


Toyota makes a GREAT product, that's why we buy them. They spent millions of dollars engineering the factory manifold to work flawlessly for many many years. I have seen too many problems with MOST headers. Most are absolute GARBAGE. I have only seen a few really quality units. But they still (unless wraped with header tape) cause severely high under hood temps. Litterally cooking everything under the hood.

There are two types of headers, one is designed with the O2 sensor at the top where it only reads from one pistons exhaust. The other type puts the O2 just before the collector. When the O2 is at the collector the EGT is too low for the factory computer and O2 to function properly which is calibrated for the stock manifold and EGT. When at the top of the header the O2 is litterally baked to death causing a quick failure, and is subject to that one cylinders reading instead of an average of them all. The factory manifold shields it from a lot of heat.

I have dealt with this problem a number of times. ICEHAWK on this board simply would not believe me when he failed his emissions test untill we put his truck back to a stock manifold after him just trying a new O2. I think he had it emission tested like 4 times while he played with it. Once back to stock with his new O2 many problems were solved including the test.

I dislike headers, But if you have to have it try putting in a new O2 first. That would be my suggestion. Also a tune up couldn't hurt. NGK V power BPR5EY (Part #1223) is a great choice. :awesomework: The cat probably would have helped. But in all my experiences with older EFI engines. A properly running engine doesn't seem to need a cat to pass with flying colors. :eeek:

Rottsa Ruck :beer:

 

[Rix]

Put a cheap-o cat in it for the test.

 

[java]

thanks for the help, ive passed with the header before, but it was a diff motor. and it didnt have a exhaust leak.
the 02 is down by the collector so maybe its not getting warm enough.
im thinking the exhaust leak is making it run rich at idle, when on the throttle, there is alot more exhaust flow so the o2 reads much better.