Gas in Engine Oil (2006 IS250)
04-29-18, 11:12 AM
#1
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Gas in Engine Oil (2006 IS250)
My Car: 2006 Lexus IS250 2.5L AWD
Milage: 175k ( last 15k by me )
Problem:
Fuel is getting into my engine oil very quickly!
I took my car to LEXUS for a routine diagnostic and they alerted me that my engine was running rich and my engine oil wreaked of fuel. I had just replaced the engine oil 200 miles prior and the vehicle has never had this issue previously. Obviously fuel is getting past my piston rings, but it seems weird that the rings would fail so catastrophically.
I've Tried:
After changing the oil again, I've been running fuel injector cleaner for 300 miles and checked the spark plug condition (they appear fine).
Has anyone had this problem or have any suggestions that don't involve a new motor?
Milage: 175k ( last 15k by me )
Problem:
Fuel is getting into my engine oil very quickly!
I took my car to LEXUS for a routine diagnostic and they alerted me that my engine was running rich and my engine oil wreaked of fuel. I had just replaced the engine oil 200 miles prior and the vehicle has never had this issue previously. Obviously fuel is getting past my piston rings, but it seems weird that the rings would fail so catastrophically.
I've Tried:
After changing the oil again, I've been running fuel injector cleaner for 300 miles and checked the spark plug condition (they appear fine).
Has anyone had this problem or have any suggestions that don't involve a new motor?
04-29-18, 12:14 PM
#3
You might verify the cold start injector on the intake is not leaking.
How? One method would be by measuring the fuel pressure. The other would be to remove it from the intake and reconnect it in the open. Switch ignition on. Mind you if it's leaking you have a huge risk for fire and explosion!!!!
Be very careful.
If this engine is in fact being flooded with fuel from either the DI or cold start injector it will take out the CATs.
You could verify some of this with Torque Pro and an OBD adapter. Look at AFR. It will be real low like under 10:1 or something.
How? One method would be by measuring the fuel pressure. The other would be to remove it from the intake and reconnect it in the open. Switch ignition on. Mind you if it's leaking you have a huge risk for fire and explosion!!!!
Be very careful.
If this engine is in fact being flooded with fuel from either the DI or cold start injector it will take out the CATs.
You could verify some of this with Torque Pro and an OBD adapter. Look at AFR. It will be real low like under 10:1 or something.
04-29-18, 07:14 PM
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You might verify the cold start injector on the intake is not leaking.
How? One method would be by measuring the fuel pressure. The other would be to remove it from the intake and reconnect it in the open. Switch ignition on. Mind you if it's leaking you have a huge risk for fire and explosion!!!!
Be very careful.
If this engine is in fact being flooded with fuel from either the DI or cold start injector it will take out the CATs.
You could verify some of this with Torque Pro and an OBD adapter. Look at AFR. It will be real low like under 10:1 or something.
How? One method would be by measuring the fuel pressure. The other would be to remove it from the intake and reconnect it in the open. Switch ignition on. Mind you if it's leaking you have a huge risk for fire and explosion!!!!
Be very careful.
If this engine is in fact being flooded with fuel from either the DI or cold start injector it will take out the CATs.
You could verify some of this with Torque Pro and an OBD adapter. Look at AFR. It will be real low like under 10:1 or something.
My AFR is pretty actually slightly high (~15:1 for 5 minutes in park). I'll definitely check on the cold start injector. Thank You
04-29-18, 09:29 PM
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I'm 100% certain there's fuel in the oil. It smells like gas and is much less viscous than it should be. I pulled all my plugs an none of them were wet nor were any of them abnormally dark indicating that cylinder was the problem.
04-30-18, 07:41 AM
#6
Optimal burn for emission purposes is 14.7:1 so during cruise and under no load like coasting it will go lean beyond 14.7 to say 15 - 20.
Optimal power is ~ 13.0:1 but under load mashing the gas the 350 hits 12.0:1 AFR.
These are all burnable mixtures if you have spark and compression at every hole. What type of daily use does this car see? Is it sitting at idle more than it is at cruise on the highway?
Optimal power is ~ 13.0:1 but under load mashing the gas the 350 hits 12.0:1 AFR.
These are all burnable mixtures if you have spark and compression at every hole. What type of daily use does this car see? Is it sitting at idle more than it is at cruise on the highway?
04-30-18, 08:29 AM
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Optimal burn for emission purposes is 14.7:1 so during cruise and under no load like coasting it will go lean beyond 14.7 to say 15 - 20.
Optimal power is ~ 13.0:1 but under load mashing the gas the 350 hits 12.0:1 AFR.
These are all burnable mixtures if you have spark and compression at every hole. What type of daily use does this car see? Is it sitting at idle more than it is at cruise on the highway?
Optimal power is ~ 13.0:1 but under load mashing the gas the 350 hits 12.0:1 AFR.
These are all burnable mixtures if you have spark and compression at every hole. What type of daily use does this car see? Is it sitting at idle more than it is at cruise on the highway?
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04-30-18, 08:42 AM
#8
If it were the AFR would be lower. Worst case is fuel being added at idle as the air demand is low. Any extra fuel would throw that off.
If you were to examine the long and short term fuel trims and both were -20.0, this indicates the ECM is taking fuel away, this would imply you have added fuel the ECU is not knowingly injecting.
The fact that at idle its at 15, says it's probably fine as leak at idle is near impossible to correct for.
If you were to examine the long and short term fuel trims and both were -20.0, this indicates the ECM is taking fuel away, this would imply you have added fuel the ECU is not knowingly injecting.
The fact that at idle its at 15, says it's probably fine as leak at idle is near impossible to correct for.
04-30-18, 09:55 AM
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If it were the AFR would be lower. Worst case is fuel being added at idle as the air demand is low. Any extra fuel would throw that off.
If you were to examine the long and short term fuel trims and both were -20.0, this indicates the ECM is taking fuel away, this would imply you have added fuel the ECU is not knowingly injecting.
The fact that at idle its at 15, says it's probably fine as leak at idle is near impossible to correct for.
If you were to examine the long and short term fuel trims and both were -20.0, this indicates the ECM is taking fuel away, this would imply you have added fuel the ECU is not knowingly injecting.
The fact that at idle its at 15, says it's probably fine as leak at idle is near impossible to correct for.
Perhaps my understanding is wrong. I thought the leak in the cold start injector (or any injector for that matter) would be present when the car was off since fuel lines stay pressurized. Presumably the excess fuel from the leak would burn off shortly after starting the car and the car would run quasi-normally while it is on. The car has no problem starting, so I don't think any of the cylinders are being flooded. Do you have any suggestions at what else might be causing my problem?
04-30-18, 11:59 AM
#10
To your point, when turned off, yes they remain under pressure until it leaks off from *a location*, injector, pump, tank, etc. And this small amount is likely to evaporate in a hot engine. That said it could land in the crankcase if the volume is excessive.
However, when in operation, leaks into the combustion chamber will force the ECU to pull back its fueling.
Assuming all cylinders have compression and the plugs can burn the fuel....
LTFT >+20, indicate air leaks. It can't supply enough fuel to maintain the trim. It is adding fuel to compensate.
LTFT <-20, indicate too much fuel (leaking injector) and the ECM is actively reducing fuel supply.
A rich AFR mixture = 10 to 14.5:1 OEM fuel MAP.
A lean AFR mixture = 14.9:1 to 20:1...
When is the last time the plugs were pulled, examined and replaced? Although it may not present P030X error, there is a good chance you have a misfire. That said, misfires (10 years ago) were per crankshaft revolution. As in the ECM would throw a P030X CEL only after 300 continuous misfires of a given cylinder. If it detects a burn and fire, the 030x is simply logged as a pending failure. So you might look in whatever tool you are using and review the pending failures. Maybe it will tell you something.
However, when in operation, leaks into the combustion chamber will force the ECU to pull back its fueling.
Assuming all cylinders have compression and the plugs can burn the fuel....
LTFT >+20, indicate air leaks. It can't supply enough fuel to maintain the trim. It is adding fuel to compensate.
LTFT <-20, indicate too much fuel (leaking injector) and the ECM is actively reducing fuel supply.
A rich AFR mixture = 10 to 14.5:1 OEM fuel MAP.
A lean AFR mixture = 14.9:1 to 20:1...
When is the last time the plugs were pulled, examined and replaced? Although it may not present P030X error, there is a good chance you have a misfire. That said, misfires (10 years ago) were per crankshaft revolution. As in the ECM would throw a P030X CEL only after 300 continuous misfires of a given cylinder. If it detects a burn and fire, the 030x is simply logged as a pending failure. So you might look in whatever tool you are using and review the pending failures. Maybe it will tell you something.
05-01-18, 10:48 AM
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To your point, when turned off, yes they remain under pressure until it leaks off from *a location*, injector, pump, tank, etc. And this small amount is likely to evaporate in a hot engine. That said it could land in the crankcase if the volume is excessive.
However, when in operation, leaks into the combustion chamber will force the ECU to pull back its fueling.
Assuming all cylinders have compression and the plugs can burn the fuel....
LTFT >+20, indicate air leaks. It can't supply enough fuel to maintain the trim. It is adding fuel to compensate.
LTFT <-20, indicate too much fuel (leaking injector) and the ECM is actively reducing fuel supply.
A rich AFR mixture = 10 to 14.5:1 OEM fuel MAP.
A lean AFR mixture = 14.9:1 to 20:1...
When is the last time the plugs were pulled, examined and replaced? Although it may not present P030X error, there is a good chance you have a misfire. That said, misfires (10 years ago) were per crankshaft revolution. As in the ECM would throw a P030X CEL only after 300 continuous misfires of a given cylinder. If it detects a burn and fire, the 030x is simply logged as a pending failure. So you might look in whatever tool you are using and review the pending failures. Maybe it will tell you something.
However, when in operation, leaks into the combustion chamber will force the ECU to pull back its fueling.
Assuming all cylinders have compression and the plugs can burn the fuel....
LTFT >+20, indicate air leaks. It can't supply enough fuel to maintain the trim. It is adding fuel to compensate.
LTFT <-20, indicate too much fuel (leaking injector) and the ECM is actively reducing fuel supply.
A rich AFR mixture = 10 to 14.5:1 OEM fuel MAP.
A lean AFR mixture = 14.9:1 to 20:1...
When is the last time the plugs were pulled, examined and replaced? Although it may not present P030X error, there is a good chance you have a misfire. That said, misfires (10 years ago) were per crankshaft revolution. As in the ECM would throw a P030X CEL only after 300 continuous misfires of a given cylinder. If it detects a burn and fire, the 030x is simply logged as a pending failure. So you might look in whatever tool you are using and review the pending failures. Maybe it will tell you something.
Since my last reply, I installed new spark plugs and determined that my cold intake injector does have a small leak. The old plugs appeared fine (e.g. none of them were dark nor when indicating that cylinder was running rich) but I went ahead and swapped them out. By small injector leak, I mean I had the car off and pulled the cold start injector from the intake manifold and let it sit on top of the manifold. I couldn't see the leak by eye, but when I came back an hour later, there was a small pool of fuel next to where it was lying. I went ahead and ordered the replacement part from Lexus. I'll update this post once I get the part installed and fresh oil (since it's saturated with fuel currently). Many Thanks
12-30-22, 06:46 PM
#12
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Any updates regarding what happened since i faced the same issue
Since my last reply, I installed new spark plugs and determined that my cold intake injector does have a small leak. The old plugs appeared fine (e.g. none of them were dark nor when indicating that cylinder was running rich) but I went ahead and swapped them out. By small injector leak, I mean I had the car off and pulled the cold start injector from the intake manifold and let it sit on top of the manifold. I couldn't see the leak by eye, but when I came back an hour later, there was a small pool of fuel next to where it was lying. I went ahead and ordered the replacement part from Lexus. I'll update this post once I get the part installed and fresh oil (since it's saturated with fuel currently). Many Thanks
any updates regarding what happened since i faced the same issue ?
12-30-22, 11:41 PM
#13
I had this issue with an ES300. Mechanic swore it was water in the oil and not gas. Said the engine was toast. I bought a used engine and had it installed somewhere else. Same thing happened with the new engine. Turns out the ECU was keeping an injector open and flooding a cylinder with gas that would leak past the rings into the oil pan.
12-30-22, 11:53 PM
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How did you solve it ?
I had this issue with an ES300. Mechanic swore it was water in the oil and not gas. Said the engine was toast. I bought a used engine and had it installed somewhere else. Same thing happened with the new engine. Turns out the ECU was keeping an injector open and flooding a cylinder with gas that would leak past the rings into the oil pan.
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