emissions help requested

[urbancynic]

Do any of you guys have any tips or tricks or any info really to lower Nox readings? the car is an 86 325e. It has a new cat and muffler, icv works fine, car idles stablly at 6-800rpm. All other readings are lower than state standards. dont know what else you might need to know? Im new to bmws so please excuse me of ignorance. :mrgreen:

[jlevie]

High NOx suggests bad catalytic converters or an engine that is running lean. Since the cats have recently been replaced, look for intake leaks, low fuel pressure, clogged injectors, of a bad AFM.

[urbancynic]

I was suggested to run it through with 1/4 tank or less and 2 qts of denatured alcohol and to also remove the air filter. then run it at 2k rpm for 15 minutes to get the cat hot and engine to temperature. I did that and ran it through emissions. Here's the readings:

Hydrocarbons .19 1.60 allowable
Carbon monoxide .84 15.00 allowable
NOX 7.21 2.50 allowable

previous test readings were:

HC .59
CO 2.72
NOX 5.91

between the last test and todays i ran a bottle of fuel injector cleaner and 91 octane fuel. Seems like its running lean to me... how do I adjust that?

[jlevie]

Running lean will be one or a combination of: intake leaks, fuel delivery problem, or AFM problem. Figuring out which is a matter of eliminating possibilities. Start by checking for intake leaks (having the intake smoke tested is the fastest and best method). The run the fuel system tests in the Bentley manual. If the problem persists, consider the AFM.

[urbancynic]

Here we go again....

So I picked up an 86 325es about a week and a half ago.

Last Sunday I spent my day replacing the timing belt, tensioner, thermostat, water pump, v-belts, air filter, and all the coolant hoses.

All that went well, although it took a bit longer than I expected. It wasn't difficult though.

Last Monday I had an issue with coolant overflowing and a bit of overheating at idle. After looking into it, I discovered that I hadn't quite bled the system properly.

Wednesday I spent my evening by jacking up the front of the car, adding coolant to the reservoir, and trying to bleed the system. Heater was running during this time. Heater output is warm, but not as hot as I was expecting.

Thursday - Tried to run it through emissions. Got the car up to operating temp before taking it in. The car did not overheat, but was getting warm, so while I waited in line I had to shut it down when I was waiting.

I ran the test on it and it failed on NOx. I don't recall exact numbers but they were something similar to this:

HC - 1.3, Max allowable - 1.6
CO - 9.43, Max Allowable - 15.0
NOx - 6.4, Max Allowable - 2.5

I was somewhat expecting this so I took it to my parent's place to do work.

I figured I NEEDED to find out why my fans weren't kicking on, so I tried to bleed the system again to no avail. The fan did kick on when jumpered on both high and low settings, but not through the switches.

New fan switches were ordered as well as a coolant temp sensor for the ecu. Plugs were removed and showed a nice brown color, but were Bosch Platinum +4's, so I replaced them with standard NGK plugs. I then ran about half a can of Seafoam through the intake and dumped the rest into the gas tank.

When the sensor and switches arrived at the parts store I picked them up and installed them. When I removed the CTS, some, but not much, coolant came out of the hole. When I removed the upper fan switch (Low speed on this car - is this correct placement, or does it not matter?) NO coolant came out. When I replaced the lower fan switch, some, but barely any came out. Coolant was added, front end jacked up, heater on, and attempted to bleed the system, but was unsuccessful as far as I can tell.

I then ran it through emissions again and the numbers were as follows:

HC - .7, max allowable 1.60 grams per mile
CO - 11.07, max allowable 15.0 grams per mile
NOx - 3.38, max allowable 2.50 grams per mile

Next day I went back to the drawing board and jumpered the low speed fan switch so I could keep it running during the wait in line, tried to bleed the coolant of air again - which I don't think worked, richened up the mixture screw on the AFM about a half a turn.

I replaced the vacuum hose from the FPR to the intake manifold as it looked pretty bad. I then sprayed around every place I could think of looking for other vacuum leaks, but found none.

I attempted to test the O2 sensor as outlined in the Bentley manual, but I'm not sure I did it right because my results were as follows:

Volts would continuously drop and keep going into the negative. I could introduce a vacuum leak (open oil filler cap), the reading would drop faster, but come back up a bit before dropping again. The reading would increase in both cases if I revved the engine.

I then took the car down for testing again. I waited in line for about 30-45 minutes and didn't need to shut the car off at all while waiting. These were my results after 3 runs on the rollers (I guess the kid didn't know how to drive the car or something):

HC - .65, max allowable 1.60
CO - 13.39, max allowable 15.00
NOx - 3.07, max allowable 2.50

I'm not really sure what to do now other than a cat and/or O2 sensor. Any ideas?