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#1
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Help interpreting X11 & EHA electrical data - '86 300E running rough!
Greetings, everyone!
I finally got around to probing my car with a digital multimeter in an effort to diagnose the rough running issue. Symptom: Rough idle, especially under load. Virtually undriveable. Engine smooths out when revved to about 4K RPM. In addition to the EHA valve, I just replaced the O2 sensor. Here's what I found: Current to EHA, Key On/Engine Off: 19.6mA Current to EHA, engine at idle: -1.5 - 3.5mA (varies) Current to EHA, idle & O2 sensor unplugged: 0.4mA X11 port, Pin3-Pin2 (measured in DC volts, since I don't have a duty cycle function) Key On, Engine Off: 3.8V (about 72%, assuming 13.7V battery) Engine idle: 6.5V-8.2V (rises steadily from 6.5 to 8.2, then drops back to 6.5 every 5 seconds or so) Engine Revving (varying speeds): 4V - 11V; varies Engine idle (warm): typical range 6.2-7.2V I discovered that the tamper-resistant cover on the mixture adjustment tower had already been removed, so I tried adjusting the mixture a bit. Using a 3mm allen wrench, I gently pressed down on the screw until I could feel it engage and I could feel resisance to turning. I adjusted the the mixture screw about 1/2 turn in either direction with the engine running and while monitoring Pin3 of the X11 port. Oddly, the voltage at Pin 3 remained virtually unchanged at 6.8V, and the engine did not seem to run any differently when he screw was turned. It seemed to have no effect. I also tried unplugging he EHA and O2 sensor with the engine running. Neither seemed to have any effect; same rough idle. Can anyone make heads or tails of this? Your input is sincerely appreciated! Mika |
#2
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What are your motor mounts like?
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#3
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I have tampered with the 3-mm allen before - half a turn in either direction is quite an adjustment. On my car just a small incremental turn made a change. Regarding your comment about the engine not responding to your fiddling - You don't feel this change instantly. I know it takes (the computer ) time to react. Were you patient enough ? Hopes this helps.
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#4
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How long should I have waited? I probably waited about 15 seconds... is that too little?
Mika Quote:
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#5
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Quote:
__________________
~Jamie _________________ 2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's. 1986 190E 2.3 Black, Auto, Mods to come soon..... |
#6
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Can anyone describe how I can test the O2 sensor I installed?
The sheath around the 1-pin connector makes it difficult to probe when connected. If I probe the singnal pin when it is disconnected, will it tell me anything useful? Thanks, Mika |
#7
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The motor mounts are pretty shot. That aside, the motor runs rough. At idle, I can hear occasional thumps. It sounds almost like someone is kicking the engine every so often. On pressing the accelerator, the engine stumbles badly, but doesn't stall anymore.
Mika Quote:
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