Quote:
Originally Posted by GaryEGJ
thank you all for your help. I tried the spark plug gap and yes it has all new cheveron supreme feul. I drove it for 120 miles still fails. Ive been asked by you to post results. So.. ASM Emission Test Results are:
%CO2 %O2 HC ppm CO% NO ppm
test rpm meas meas max ave meas max ave meas max ave meas
15 1582 14.6 0.0 105 41 101 .69 .05 .04 530 175 55
25 1609 14.6 0.0 80 30 103 .56 .05 .05 487 138 52
15mph passes the 25mph fails.
SORRY THIS THING WILL NOT FORMAT THE PAGE RIGHT. i WRITE IT OUT SO ITS LINED UP BUT WHEN IT POSTS IT DOESNT STAY
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These are very good numbers for a M103 other than HC, and the fact that O2 is 0.0 means the O2 sensor and catalyst are working well.
That leaves excess misfires as the source of the high HC.
What make/model of spark plugs are in the car?
The ignition system is designed for non-resistor plugs (lots of archive discussion on this issue), but they are getting hard to find. Resistor plugs alter the voltage wave form and reduce spark energy at the plug, which can lead to exess misfires - often not enough to notice, but it can show up in the emission test.
RFI resistors are built into the spark plug boots and the distributor cap. The wires should measure about 2K ohms. Pull and twist on them slightly them while testing. It's possible that the plug wires on a lot of M103s have been damaged by pulling the wires off the plugs by hand. I have a special tool that I bought way back when that grabs the metal RFI shield, so no stress is placed on the wire iteself.
There is also a 1 or 2K ohm resistor in the distributor cap towers. My OE cap had a "flaky" tower that would show the proper resistance when holding the cap loosely, but then go to infinity if I put some thumb pressure on the side of the tower, so I replaced the cap.
The combination of resistor plugs and the flaky cap almost caused my car to bust the 100 ppm HC idle limit in the 1995 two-speed no load test. A new cap and going back to proper Bosch non-resistor plugs dropped the idle HC from 100 ppm in '95 to 22 in the '97 two-speed no load test.
Concentrate your effort on testing secondary ignition system components and make sure you have OE equivalent non-resistor plugs installed.
BTW, use periods instead of spaces to line up the data under the proper headings. The software ignores extra spaces but will recognize periods to keep the columns reasonably aligned for easier reading. These are the ASM test results for my '88 190E 2.6 five-speed, done about two weeks ago.
...............CO2....O2............HC...................CO..................NOx
test..rpm..meas..meas..max..ave..meas..max..ave..meas..max..ave..meas
15...1587..15.0...0.0....116...27.....55...0.74..0.09..0.28...791..255...32
25...2638..15.1...0.0.....91...18.....17....0.62..0.07..0.13...730..223...42
Duke