: Gas smell in oil, black exhaust tips, backfiring, ADVICE PLEASE!



ABest62
01-04-12, 10:49 PM
I just checked my oil and it smells like it has gas in it. This oil is new (80 miles). I just thought, at first, that the Mobile 1 extended performance oil smelled funny, but the gas smell is pretty distict now.
Also, my exhaust tips turn black within a day if I dont put race fuel in the tank. Typically, I do 4 gallons 100 octane with 10 gallons of 91, but I cant always get 100 octane as it is very limited in Vegas. Vegas doesnt have 93,, stupid!!. I also get backfiring/popping between shifts or while decelerating way more on 91 octane. I attributed this to the big cam and 93 octane tune (done on East coast where 93 is readily available I assume).

Anyway, if anyone has had this problem, or knows what to do to fix this,, please share!

List of Performance Mods:
Lingenfelter 2.55" upper supercharger pulley
Lingenfelter 9.1" crank pulley
Lingenfelter CAI
Lingenfelter GT9 blower camshaft
Lingenfelter valve springs and push rods
Tuning by Redline Motorsports
Corsa Sport Exhaust

EVIL_C5
01-05-12, 07:29 AM
I was having similar issues and found that the car was running very lean at part throttle and thru transitions. you take that along with TQ Management where the PCM is pulling timing between shifts and also dumping fuel in to compensate for the lean condition, it made mine stutter and pop.

I had to log many miles of driving to get anywhere on it.

WhoseCadillacIsThat
01-05-12, 07:34 AM
This is serious business! You either have an injector (or injectors) weeping fuel pressure off the rail or basically dumping fuel. (Strange part is a backfire is a symptom of a lean burn condition....) In any case the cylinder walls are being washed by excess fuel which winds up in the crankcase so oil is no longer present up on the cylinder walls and scoring will result. This scoring will eventually destroy a piston since the rings are likely to seize against an un-lubricated cylinder wall. Check with your tuners.... Fuel in the oil is quick death to an engine.

GreaseMonkey
01-05-12, 08:22 AM
This is serious business! You either have an injector (or injectors) weeping fuel pressure off the rail or basically dumping fuel. (Strange part is a backfire is a symptom of a lean burn condition....) In any case the cylinder walls are being washed by excess fuel which winds up in the crankcase so oil is no longer present up on the cylinder walls and scoring will result. This scoring will eventually destroy a piston since the rings are likely to seize against an un-lubricated cylinder wall. Check with your tuners.... Fuel in the oil is quick death to an engine.

This. A backfire can be caused by the engine running rich as well. It's simply anytime there is excess fuel that makes it out of the combustion chamber. A lean can cause it because there wasn't optimal combustion, and a rich mixture can cause it for the same reason.

To the OP, no CEL or have you been able to pull codes (inactive or active)?

Fireverm
01-05-12, 01:21 PM
Auto or manual? Are you getting actual backfiring or just some popping and gargling between shifts or decelerating? If it's a manual you will get that with that exhaust and it is normal thing because of the different back pressure.

I currently have just a CAI and Corsa sports and it does that popping whether I have a tune in or not.

Why don't you get it re-tuned for 91 if you think it has a 93 tune in it and save yourself a bunch of hassle? There are so few pumps in this town that offer 100.

ABest62
01-05-12, 01:54 PM
Thanks for the replies! No I have not gotten any CELs. The car is a manual and I did expect the popping between shifts and during deceleration, it actually sounds great,, but it does it worse when running 91 octane, and will even do mild real backfires between shifts when it is colder (nothing like the full-on backfires that sound like a bomb going off).. Like I said, I just figured with the increased duration and lift of the cam, some fuel was making it past the exhaust valves. The wierd part is that I checked the oil all the time and always rub the oil between my fingers and smell it (just a habit Ive had for years to check for gas or coolant in the oil).. And it never smelled like gas until RIGHT after I had Mobil 1 Extended Performance put in (maybe 80-100 miles ago as of now). That doesnt seem like a coincidence to me..

I would like to get a 91 tune done just to make sure, but I dont know of a good place in Vegas and I'm surely not taking it back to Redline in NY. I just had it dynoed at Shelby Motorsports a couple months ago and everything seemed good to go, even the A/F ratio. They didnt say anything to the contrary. I guess I could have them tune it, even though they primarily deal with GT500s,,, if they can do Super Snakes, they should be able to do an LSA.. I have attached the dyno sheet. Do the AF ratios look good to you guys?

WhoseCadillacIsThat
01-05-12, 02:18 PM
This. A backfire can be caused by the engine running rich as well. It's simply anytime there is excess fuel that makes it out of the combustion chamber. A lean can cause it because there wasn't optimal combustion, and a rich mixture can cause it for the same reason.

To the OP, no CEL or have you been able to pull codes (inactive or active)?

Wrong.... what happens if you turn the oxygen off first on a oxyacetylene torch? Nothing - but a stream of soot. Try turning the acetylene off first - backfire! Same scenario in an internal combustion engine.... Textbook: backfire is caused by a lean burn condition - not a rich condition. A flooded engine does not backfire - it just doesn't fire at all.

Now back to the OP.

ABest62
01-05-12, 03:40 PM
From what EVIL was saying, his car does the same. It is only between shifts that I get a small backfire/pop now and then and mostly before reaching full operating temp and while running 91 octane. The car overall runs like a striped ape as you can probably tell by the dyno. My main concern is the gas-like smell in the oil and maybe the blackening of the exhaust tips so quickly. A 91 octane tune would probably help with the black tips, but I'm not so sure about the gas smell.

If anyone else is running Mobile 1 Extended Performance, please smell your dipstick. Strange request I know, but maybe this oil just smells weird compared to regular Mobil 1??

----------


I was having similar issues and found that the car was running very lean at part throttle and thru transitions. you take that along with TQ Management where the PCM is pulling timing between shifts and also dumping fuel in to compensate for the lean condition, it made mine stutter and pop.

I had to log many miles of driving to get anywhere on it.

EVIL, what do you mean when you say you had to log many miles to get anywhere on it? Did it clear itself up after a while?

GreaseMonkey
01-06-12, 07:25 AM
Wrong.... what happens if you turn the oxygen off first on a oxyacetylene torch? Nothing - but a stream of soot. Try turning the acetylene off first - backfire! Same scenario in an internal combustion engine.... Textbook: backfire is caused by a lean burn condition - not a rich condition. A flooded engine does not backfire - it just doesn't fire at all.

Now back to the OP.

If it's rich enough it will flood, but too rich of a condition that will still combust but not fully will still cause a backfire. Lean conditions are usually the cause, however when there is a concern of fuel smell in the oil there is something going on other than a lean condition.


A backfire occurs when there is an imbalance in the air to fuel ratio required for your vehicle to operate properly. If the fuel mixture is too lean (not enough fuel) you may have a backfire in the intake, or too rich (too much fuel) you may get a backfire out of the exhaust system. Most backfires are easily repaired by correcting the imbalance and providing a greater or lesser percentage of fuel to the mixture.

http://www.2carpros.com/articles/what-is-an-engine-backfire

Dogbreath
01-06-12, 09:03 AM
I'd bet that your tune is fine and that this is not related to the oil. You have either a leaky injector or more likely a failed sensor that is telling the computer that the engine is running lean and therefore dumps more fuel. Have somebody with a good reader check the fuel trims.

ABest62
01-20-12, 11:54 AM
Just a quick update. I put Mobil 1 Extended Performance in my Titan right after my first post and believe it or not the oil smelled just like the oil in my V after 50-60 miles. It is a strange smelling oil, nothing like regular Mobil 1 synthetic. Has a fuel-like smell. Hard to explain, guess you'd just havta try yourself. Either way, it is a relief.

As for black exhaust and popping,, I decided to run race gas/91 mix every fill up until I get the headers installed and a 91 tune done. I think I got some bad gas the day I decided to post this thread cause I had filled up at some random station across town that I had never been before and it got way worse (kinda freaked me out). The car runs perfect with 4 gal 100oct / 10 gal 91 oct. Just regular popping (sounds great) and the tips stay clean for several days.
I decided that I will go with Shelby for the tune after the header install. I will post the results when the time comes.

But 1st Im getting brembo 2 peice rotors, cause I'm sick of looking at rust on an otherwise flawless car! (and getting new HAWK PC pads to reduce the brake dust).

WhoseCadillacIsThat
01-22-12, 08:49 AM
Just a quick update. I put Mobil 1 Extended Performance in my Titan right after my first post and believe it or not the oil smelled just like the oil in my V after 50-60 miles. It is a strange smelling oil, nothing like regular Mobil 1 synthetic. Has a fuel-like smell. Hard to explain, guess you'd just havta try yourself. Either way, it is a relief.

As for black exhaust and popping,, I decided to run race gas/91 mix every fill up until I get the headers installed and a 91 tune done. I think I got some bad gas the day I decided to post this thread cause I had filled up at some random station across town that I had never been before and it got way worse (kinda freaked me out). The car runs perfect with 4 gal 100oct / 10 gal 91 oct. Just regular popping (sounds great) and the tips stay clean for several days.
I decided that I will go with Shelby for the tune after the header install. I will post the results when the time comes.

But 1st Im getting brembo 2 peice rotors, cause I'm sick of looking at rust on an otherwise flawless car! (and getting new HAWK PC pads to reduce the brake dust).

Since you brought up the rotors....(don't enjoy the rust look either!) what about the new rotors from GM that have a heat treated graphite non rusting surface...?