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Discussion Starter #1 (Edited)
So, as part of my recent refresh of the engine, I pulled a sample and sent it to blackstone-- came back with 5% fuel with only 3000 miles on the oil.

Compression/leakdown numbers for the engine are fine. Car has no MAFs, so they're not the problem. Before I got these numbers back, as part of my engine refresh I already did all four CPS's, both TPS's, thermostat, changed the air filters and the pre cat 02's, had the fuel injectors rebuilt, and replaced the oil separator system.

I did not replace the spark plugs, but I have documentation that they were replaced 15,000 miles ago.

No codes.

Now, the fuel dilution occurred before I replaced all of the above. So, question is... are there any possible contributors to it that I haven't already replaced?
 

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Doesn't jive with the "didn't seem to dilute" comment, but how about:
- a tstat on it's way out
- sampling after a series of short trips
- sampling without running the engine hot first
 

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Discussion Starter #3 (Edited)
Doesn't jive with the "didn't seem to dilute" comment, but how about:
- a tstat on it's way out
- sampling after a series of short trips
- sampling without running the engine hot first
Actually, I did change the thermostat too, as it had been running too cool (around the 2nd mark on the coolant gauge, if you count them as 4 total).

Sample was taken dead cold.

But... 5% is HIGH!
 

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5% is high. Action is warranted.

You need to hook up a computer and start looking at "stuff other than codes". We tend to be code centric, but that leaves much out of the picture...

Is your car running rich?? You can have issues so that overall the trims stay within bounds but in specific RPM bands it is out of whack- so the DME never gets bad enough to set codes, but excessive fuel is washing the cylinders and getting injected into the oil. Are your wear metals indicative of this kind of thing? I dunno, and also not surprised blackstone gave you a kind of non-answer...

How are the tailpipes, rear bumper?
 

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Have you started up the motor for a very short period of time and shut it off. This can cause fuel to go into the oil.
 

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Take the car out for a good cruise and get it properly warm and do a new draw and re-test. This will, at least partially, answer if the high fuel content is a result of a cold draw or other contamination of the sample. Check, as ARD already pointed out, your fuel trims and injector duty cycle. Also, you should perform an injector leak test because nobody likes a hydro-locked engine.
 

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Is it possible the lab mixed up the samples?
 

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Discussion Starter #12
Google oil sampling. It should ALWAYS be done with the oil hot and within 30 minutes of engine shutdown. Otherwise it's just not representative.
Good to know!

I suspect my fuel dilution did exist, but now that I remember that one of my fuel injectors was flowing excessively, seems like the probably cause.

I'll resample (correctly this time) in 3000 miles to verify the issue is gone, but I'm pretty confident it's addressed at this point.
 
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