Avocado Roll
New Member
The Test: I just took my car to Air-Care, and it Failed based on high Hydrocarbons at idle. This relates to unburned fuel. The HC reading came up at 390ppm, where the maximum is 114ppm, (avg statistical pass reading is 13ppm!). It passed all other tests.
My Setup: The car has an aftermarket air-filter, as well as Cat->back exhaust. New Distributor, Wires, Plugs (<6months).
Diagnostics & Hints:
Air Care Readings:
Thanks for the help!!!
My Setup: The car has an aftermarket air-filter, as well as Cat->back exhaust. New Distributor, Wires, Plugs (<6months).
Diagnostics & Hints:
- The car will maintain a high idle (1500rpms) until it fully warms up. About 5 minutes in, as the temp reaches warmed/operating level, the idle lopes between 1500 & normal idle speed. It will hang at 1500 for about a second, drop rapidly down and rapidly back up and hang at 1500rpms again. Depending on outside temperature, this could last for 1-3 minutes.
- Oxygen sensor: Previous owner installed a replacement, but the body is crimped slightly. I tested the voltage it was putting out. As the car warmed up, it got to a loop of 0.5 - 1.2 volts. At one point (randomly) it held a voltage of 2.0-3.0 for about 10 seconds, but I saw this once and could not repeat it. (Haynes Manual says it should be between 0.1-0.9 volts - could mine be different because of my high flow air filter or does this indicate a problem elsewhere, or is it defective???)
- Distributor: When the previous owner installed the distributor, he slapped it on with no adjustment to timing!!! He ran 94 octane b/c it was WAY too advanced. it pinged badly at half-throttle below 4000rpms with 87octane fuel. I retarded the timing and it ran smoothly on 87 fuel AND had more kick at 4500rpms. Strangely enough, over time, it started pinging again more, and I retarded the timing further. This relieved the pinging and then a month later I notice the pinging coming back again between 2000-3500 rpms at FOP in higher gears.
- Running Synthetic 10W30. Oil level drops roughly under 1L / 1000km. Noticed oil leaking from valve cover and tightened it, which seemed to fix it (previous owner did not tighten anything enough!) Could it be burning some oil as well? Would this bring HC count to 390ppm?
- Electrical: When I add headlights + fog lights (~350W total) the idle will usually drop about... ~80 rpms? Wondering if the alternator or battery are ok. Sound system works great and car always turns over quickly and starts well.
- Spark plugs - pulled them out after a long idle: they look fine: tip electrode is black and arch electrode is brownish. They did have an interesting smell though.
- Below are pics of the Air Care readings. Notice on the HC scale - stays just below maximum allowable for 6 seconds, then spikes to 661ppm! then fluctuates at over 300ppm. Notice also the closely related O2 readings with a spike just after HC readings fly up.
- Back of the car has a huge soot that builds up over time around the exhaust tip
Air Care Readings:
Thanks for the help!!!
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