GS300 Running a little rich - Failing Smog!
03-20-14, 09:37 PM
#1
GS300 Running a little rich - Failing Smog!
I have a 1998 Lexus GS300 with about 128,000 miles on it. Over the course of three months Ive been doing a few things to prepare my car for this dreaded day. Ive replaced the timing belt, vvt-i solenoid, valve cover and cam seals, spark plugs, coil pack wires and the oil was changed. The entire time Ive owned the car Ive only been running on premium grade fuel.
I went it for a smog on my first visit to the shop and failed because my Hydro Carbons were a bit high. Just barely they said. I took it in to a mechanic who hooked it up to a computer for a diagnostic check and he says everything looks perfect. I told him I suspected the spark plugs because when I had bought them, the gentleman at the counter had gapped all of them right in front of me. Both the mechanic and Lexus dealer told me he was not supposed to gap dual electrode plugs with precious metals. So I replaced my new plugs with a new set of OEM Denso plugs from the Lexus dealer and took it back in for a smog. I failed again on my second visit. This time the results were worse. Everything else is passing. Im just failing emissions. If someone with experience can shed some light on this, I would greatly appreciate it.
I went it for a smog on my first visit to the shop and failed because my Hydro Carbons were a bit high. Just barely they said. I took it in to a mechanic who hooked it up to a computer for a diagnostic check and he says everything looks perfect. I told him I suspected the spark plugs because when I had bought them, the gentleman at the counter had gapped all of them right in front of me. Both the mechanic and Lexus dealer told me he was not supposed to gap dual electrode plugs with precious metals. So I replaced my new plugs with a new set of OEM Denso plugs from the Lexus dealer and took it back in for a smog. I failed again on my second visit. This time the results were worse. Everything else is passing. Im just failing emissions. If someone with experience can shed some light on this, I would greatly appreciate it.
03-21-14, 08:43 PM
#4
Just a little update for those who might be on the same boat...
After doing a bit of google research, I noticed a common theme. Since I've owned my GS I've been experiencing oil related issues. My VVTi gear leaked pretty bad so I rebuilt it. A CEL came up for a blocked Oil Control Valve. I replaced the screen which was clogged by oil residue. A week later my car stalls. Same CEL code came up. I replaced my OCV solenoid. When I had examined it, it was caked so bad with oil which was like the cause of failure. From time to time I get a burnt oil smell coming from the engine bay but there are no leaks.
It's all leading to contaminated oil. Oil releases hydrocarbons from the crank case through the PCV valve which then gets burned off inside the engine. Contaminated oil will produce higher amounts of HC which can lead to a rich mixture causing me to fail emissions. On my results report I was failing because of high Hydro Carbons.
I've only owned the car for two oil changes. I use nothing but Eneos 5-30w synthetics. I suspect the previous owned hardly ever changed the oil and he/she did, they probably used conventionals. That resulted in higher HCs which created engine oil deposit build up.
I'm going to buy the AMSoil engine flush and another 6 quarts of Eneos oil. I'll also pour in a bottle of injector cleaner and maybe some race gas and run that beast up and down the highway before I stop at the smog station.
After doing a bit of google research, I noticed a common theme. Since I've owned my GS I've been experiencing oil related issues. My VVTi gear leaked pretty bad so I rebuilt it. A CEL came up for a blocked Oil Control Valve. I replaced the screen which was clogged by oil residue. A week later my car stalls. Same CEL code came up. I replaced my OCV solenoid. When I had examined it, it was caked so bad with oil which was like the cause of failure. From time to time I get a burnt oil smell coming from the engine bay but there are no leaks.
It's all leading to contaminated oil. Oil releases hydrocarbons from the crank case through the PCV valve which then gets burned off inside the engine. Contaminated oil will produce higher amounts of HC which can lead to a rich mixture causing me to fail emissions. On my results report I was failing because of high Hydro Carbons.
I've only owned the car for two oil changes. I use nothing but Eneos 5-30w synthetics. I suspect the previous owned hardly ever changed the oil and he/she did, they probably used conventionals. That resulted in higher HCs which created engine oil deposit build up.
I'm going to buy the AMSoil engine flush and another 6 quarts of Eneos oil. I'll also pour in a bottle of injector cleaner and maybe some race gas and run that beast up and down the highway before I stop at the smog station.
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