Octane ratings and hard starts

HemiETR · 12-03-2004, 08:08 PM

Titan was very sluggish on startup with the high octane 93 rating. I called the service manager and he said I should switch to low grade 87 octane. Since then I've had no sluggish problems on start up. Have any of you had the same problem? Or are all of you running the low grade?

Thanks

honeykeeper · 12-03-2004, 08:27 PM

low grade so far 3,000 miles too.

Ape0r · 12-03-2004, 09:37 PM

"Low grade" really isn't a very good way to describe 87 octaine fuel. 87 octaine fuel isn't of lower quality than 93 octane, it simply burns more easily. Octane refers to the fuels "resistence" to combustion. The lower the octane rating, the lower the burning temp of the fuel. Of course, burning temp is affected by outside variables too, such as temperature and pressure. Engines that require high octane fuel are designed with higher compression ratios to increase power, e.g. high pressure. If you put 87 into an engine that demands 93, it will combust before the cylinder has reached TDC (top dead center), and cause knock. However, what you should draw from the above is that 87 burns more EASILY. Should definitely help out with cold starts. My '04 Chevy has never had anything but 87, and I'm keepin' it that way.

Using higher octane fuel than your engine requires can actually cause carbon buildup! However, I think I remember hearing something about the Titan manual saying something about how you should use high octane for the best performance, so I wouldn't worry about that with your Titan. You might want to use 87 when it is cold outside, though. Personally, I'd use 87 all the time, just to save a few bucks.

*OnebadSE* · 12-03-2004, 10:07 PM

I use 93 octane and have no problems. I used to use plain ole 87 but find my truck to be a bit more peppy with the 93. If yours acts better on 87, use 87. All vehicles, even of the same make and model, are different in some ways.

Half Shovel · 12-03-2004, 10:41 PM

I really don't mean this to offend anyone, but DAMN I wish people would do a search before more octane threads. Use 87 octane in your Titan - it's that simple.

HS

Titan Power · 12-03-2004, 11:32 PM

There are many more variables to gasoline then just octane. How many times did this happen? Once? Thirty? If it was only once, it could be a number of things. Detonation resistance and volitility are not exactly the same things. Gas of the same octane is not even the same year round. It the summer the mix is less volitile to reduce evaporative emissions. In the winter it is more so to help with cold starts. Often, temps will drop earlier then expected, and the stations still have the summer formula. Then many cars can have trouble starting. That possibility is much more likely, or perhaps a bad batch of gas. I've run 118 octane race gas in my other car, with a low compression turbo engine, with no starting issues. The Titan shouldn't have any difficulty with it's excellent ignition system, head design, and engine management. Either that or there is a problem with your truck.

Jason K.

*OnebadSE* · 12-04-2004, 12:26 AM

Quote:

Originally Posted by Half Shovel

I really don't mean this to offend anyone, but DAMN I wish people would do a search before more octane threads. Use 87 octane in your Titan - it's that simple.

HS

What's "that simple" is you thinking everyone has to conform to your thinking. My truck is quicker, more powerful running on 93 than on 87, and I can well afford the minimal cost difference. Stop believing everything you read and try things for yourself. Experience wins every time.

BiXLL · 12-04-2004, 07:14 AM

LOL, here we go again! Some guys just enjoy paying more, feeling the more they pay, the better it runs.

HemiETR · 12-04-2004, 07:49 AM

Quote:

Originally Posted by Titan Power

There are many more variables to gasoline then just octane. How many times did this happen? Once? Thirty? If it was only once, it could be a number of things. Detonation resistance and volitility are not exactly the same things. Gas of the same octane is not even the same year round. It the summer the mix is less volitile to reduce evaporative emissions. In the winter it is more so to help with cold starts. Often, temps will drop earlier then expected, and the stations still have the summer formula. Then many cars can have trouble starting. That possibility is much more likely, or perhaps a bad batch of gas. I've run 118 octane race gas in my other car, with a low compression turbo engine, with no starting issues. The Titan shouldn't have any difficulty with it's excellent ignition system, head design, and engine management. Either that or there is a problem with your truck.

Jason K.

It happened till I switched to 87. I'm thinking its bad batch of gas though. I run the Air Force Base Gas consistently and I have the same type of problem with my Toyota Camry. I'll try a different gas station.

Thanks

HemiETR · 12-04-2004, 07:59 AM

Quote:

Originally Posted by Half Shovel

I really don't mean this to offend anyone, but DAMN I wish people would do a search before more octane threads. Use 87 octane in your Titan - it's that simple.

HS

HS

Thanks for your input. If you feel as though people are boring you, don't waste your time and reply to their thread - it's that simple.

HEMI-SMOKER · 12-04-2004, 08:23 AM

I Cant Tell Any Difference In Performance With 87 Or 93, However I Have Pre-ignition Knock No Matter Which I Use. Especially Before It Warms Up. Not As Bad Then And This Is Only When I'm Steeping On It.i Told My Dealer And He Said I Should Run 93. Does Every One Have Pre-ignition. I Also Notice That My Injectors Are Awfullly Loud

SE 4X4 OFFROAD BIG TOW

*OnebadSE* · 12-04-2004, 09:21 AM

Quote:

Originally Posted by HEMI-SMOKER

I Cant Tell Any Difference In Performance With 87 Or 93, However I Have Pre-ignition Knock No Matter Which I Use. Especially Before It Warms Up. Not As Bad Then And This Is Only When I'm Steeping On It.i Told My Dealer And He Said I Should Run 93. Does Every One Have Pre-ignition. I Also Notice That My Injectors Are Awfullly Loud

SE 4X4 OFFROAD BIG TOW

I've never heard of a vehicle with a knock sensor that knocked. I think you're hearing something other than pre-ignition. I've used both regular and premium, neither had any effect on noise in my truck.
Anyone caring to try using premium to see its' effects, remember that it'll take a tankful or two of premium before the ECU can change mapping but, you'll notice the difference. You may then decide it's not worth the extra $$$ but it's very noticable. There have been dynos on this forum proving a slightly faster truck with it.

PS, do your homework, the Titans V8 Endurance engine most definitely IS a high compression engine. It's 9.80/1 to be exact.

HEMI-SMOKER · 12-04-2004, 11:14 AM

Quote:

Originally Posted by OnebadSE

I've never heard of a vehicle with a knock sensor that knocked. I think you're hearing something other than pre-ignition. I've used both regular and premium, neither had any effect on noise in my truck.
Anyone caring to try using premium to see its' effects, remember that it'll take a tankful or two of premium before the ECU can change mapping but, you'll notice the difference. You may then decide it's not worth the extra $$$ but it's very noticable. There have been dynos on this forum proving a slightly faster truck with it.

PS, do your homework, the Titans V8 Endurance engine most definitely IS a high compression engine. It's 9.80/1 to be exact.

THANX. I THINK I'M JUST HEARING LOUD INJECTORS OR MAYBE I'M JUST GOIN NUTS. THE DEALER AND MECHANIC (WHO OWNES A TITAN) SAID IT SOUNDS NORMAL.MAYBE I SHOULD QUIT BEING SO ANAL AND JUST ENJOY MY AWESOME TRUCK!!!!!!!!!!!!!!!!!!!! I LOVE MY TITAN!!!!!!!!!!!!

JS02 · 12-04-2004, 12:55 PM

I have used 87 octane for about 15000 miles and tried 91 octane for the last 13000 miles. I have not had any starting problems at all. The Titan doeas seem to run better. But I don't race the truck and have not put it on a dyno so I can't say for sure. The mpg has increased about 7-8%. 91 octane fuel costs about 5% more for me so I feel there is no increased cost. I do know from my experience racing my Buick Grand National that increased timing improves power and generally requires more octane. Juma saw by using a scanner that the Titan would increase the timing with higher octane fuel after the first tank or so. It may be that the more agressive you drive the more the increased octane will show up. I'm sure the quality of fuel also has some effect too.
When I first started driving my truck I used 87 octane. I tow a lot and generally use my Titan pretty hard. I too didn't feel there was any advantage to higher octane fuel. Now I have compared both over a lot of miles and I feel there is a difference. It is definitely not a simple answer. High octane used to be used for engines iwth higher compression ration and advanced timing. Now we have compression ratios that are very comperable to some of the high compression engines of the past and do it with electronics. It makes sense to me that if the engine electronics can be computer adjusted to work better with higher octane fuel then it could improve the performance of the engine.

Half Shovel · 12-04-2004, 01:44 PM

Quote:

Originally Posted by HemiETR

HS

Thanks for your input. If you feel as though people are boring you, don't waste your time and reply to their thread - it's that simple.

Hemi,
Ok, I'll eat some humble pie here. What I should have said was "there are 5,327 threads on this topic on TT already, please refer to them".

You're right, I'm bored with the octane threads, because folks keep saying "Will I get more performance out of high octane gas" or "I get more performance out of my truck by using 93 octane gas". Unless the Titan's ECU is programmed to advance timing until it detects knock (taking advantage of the higher knock-resistance of 93 over 87), you're wasting your money. You're also risking turning your truck into an octane "junkie", a very real phenomenon.

I don't know if the Titan's ECU does this (see other threads on this particular element of the octane/engine discussions), but my guess is that it doesn't because of emissions and mileage considerations. If anyone knows the answer to this, post it. I think I do remember seeing something about it somewhere...

Consider this - if the Titan motor did actually get better performance out of higher octane gas, wouldn't Nissan recommend it for "optimal performance", or wouldn't this idea be all over every auto mag? I never see it, and I read MT, C&D, Automobile, and a few off road mags pretty regularly. I mean jeez - talk about an easy mod!

So I'll kwit mah *****in', but people, please at least do a search for this before starting yet ANOTHER octane thread. I honestly don't know why this topic puts a bee in my bonnet....must be the boredom thing you mentioned.

HS