Failed Air-Care! --> High HydroCarbons at Idle

[Avocado Roll]

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:

• 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

My Guesses: O2 sensor? Idle Air Control Valve? Fuel Injectors? Battery/Alternator?

Air Care Readings:

Thanks for the help!!!

 

[sexystover]

fix the 02 sensor and clean ur throttle body and IAC, the car should not idle hunt (jump between 1500 and idle) once it is warm it should be a steady idle somwhere just below 1000rpm

also check for any stored codes

 

[Avocado Roll]

Thanks Sexy - will install my new O2 Sensor.

How do you reccomend I clean the Throttle body and IAC?

Just about to run tests on IAC valve now. This may fix the idle loping (although the car idles fine when fully warmed up) but is this likely to resolve the high hydrocarbon count?\

Other Suggestions?

 

[sexystover]

get a can of carb cleaner its only a few bux at walmart or autozone and just go to town with a can of that and a toothbrush/small wire brush. when you start the car the idle will be high because of the carb cleaner u used to clean it but the idle will come back to normal after it burns it off, had a similar problem on a scion tc, cleaned the throttle body and iac with carb cleaner, started it up and let it idle for a few minutes and it fixed the weird idle problem

 

[jdmjim]

being that youe Cos are ok HCs is usually ignition related. find the idle problem and im sure youll fix the high readngs

 

[AcurInteg96]

Thanks Sexy - will install my new O2 Sensor.

How do you reccomend I clean the Throttle body and IAC?

Just about to run tests on IAC valve now. This may fix the idle loping (although the car idles fine when fully warmed up) but is this likely to resolve the high hydrocarbon count?\

Other Suggestions?

:rolf:

 

[Avocado Roll]

Did some further work:

Tested Idle Air Control Valve (IAC). It seems to be doing it's job, but it does hesitate when the car is half warm. About the idle though: take note that the car does carry a steady idle when fully warmed up. I will still clean the throttle body with the brush as suggested.

I did not yet install the new O2 sensor (if I do, I can not return it). 1)I want to test the fuel pressure regulator - if pressure is too high, it may be the problem. 2)Also want to test the injectors for a leaky one.

As for the O2 sensor, the higher voltages it is putting out is likely in response to the rich mixture that already exists.

JDMjim, As for ignition: plugs, wires, distributor are new. Battery Voltage reading was fine. Should I further retard the timing until it doesn't ping at all - or is this pinging caused by something else (right now it's very minor, higher gears, open throttle at 2000-3000ish rpms.)

What do you think?

Further thoughts?

 

[sexystover]

im not sure if theres timing marks on the crank pulley (i dont own a teg yet) but i would try to borrow a timing light if there are and actually check your timing to it can be set to factory settings instead of guestimating

 

[Avocado Roll]

So on my to-do list:

-Clean throttle body (how do you suggest I get to the IAC valve?... w/ the brush or just the throttle body cleaner?)
-Test fuel pressure
-Adjust timing with strobe/timing light

Timing adjustment should help, though I doubt the slight advance is causing HC readings 3-6x the allowable amount.

 

[sexystover]

for cleaning the IAC just spray the TB cleaner in it and turn the key on/off to get it to move

 

[kfed]

I had a toyota tested and my timing was advanced 5 degrees. It barely passed some of the emission readings, but when i set the timing to where it should be I had 50%-70% less readings. So, timing may be a big help in emissions. Idle should be around 750 plus minus 50 rpms. Cold idle should be between 1000 to 2000 rpms

 

[Avocado Roll]

I see - good call on the timing in that case. Will have some time to do work on the car later this week. I will do all items listed in post above and let you guys know.

 

[Avocado Roll]

Unresolved

So here's what I've done

-Tested Fuel pressure and regulator - OK
-Cleaned Throttle body
-Replaced O2 Sensor
-Replaced IAC Valve (idling better now)
-Tuned to factory timing

Runs well now but testing the O2 sensor I now get open loop (solid) readings at 12 or 13 V from both new and old sensor... (the old one used to to a closed loop w/ high readings even that's better!)

Help?

 

[Samurai_Blue]

use an aem or stock intake. and is your cat good?

 

[Avocado Roll]

cat should be good as it is pretty new and all other readings pass.

I have an AEM filter & tube