Pinging with 87 octane

[alw]

Ok, we've discussed this before in other threads, but I wanted to see if anyone else has this too.

If I run 87 AKI (AKI is the rating at all gas pumps in the U.S. r+m/2) gas, my truck pings like crazy. Service guy says Nissan recommends 91 AKI or higher gas if you have pinging. He says the pinging I hear is the computer adjusting the timing to make up for the gas and that Nissan doed not really enforce the higher octane requirement.

I thought the Titan was speced to run 87 AKI gas!

[bestatchess]

Originally Posted by alw

He says the pinging I hear is the computer adjusting the timing to make up for the gas

Huh? The pinging, also known as "detonation" indicates that the octane rating of the fuel is too low for the current conditions of the engine. Under these circumstances, one would expect that if the computer is adjusting anything, it would be retarding the timing which would tend to stop the pinging. (along the same line, the aftermarket chip mods do the opposite, advancing the timing to run at higher compression and requiring the use of higher octane gas to get a little more HP) Maybe the dealer meant that it will take some time for the computer to adjust the timing to stop the pinging? Did you switch from 91 down to 87 when the pinging started?

Maybe you got some crappy gas? Have you tried different brands of 87 octane? If your truck won't run without pinging on good quality 87, I think it would be an indication that the computer is not correctly adjusting the timing.

[alw]

Originally Posted by bestatchess

Huh? The pinging, also known as "detonation" indicates that the octane rating of the fuel is too low for the current conditions of the engine. Under these circumstances, one would expect that if the computer is adjusting anything, it would be retarding the timing which would tend to stop the pinging. (along the same line, the aftermarket chip mods do the opposite, advancing the timing to run at higher compression and requiring the use of higher octane gas to get a little more HP) Maybe the dealer meant that it will take some time for the computer to adjust the timing to stop the pinging? Did you switch from 91 down to 87 when the pinging started?

Maybe you got some crappy gas? Have you tried different brands of 87 octane? If your truck won't run without pinging on good quality 87, I think it would be an indication that the computer is not correctly adjusting the timing.

Yes, this was after 5 tanks of gas from different stations. Should it take 5 tanks for the computer to adjust?

[Deepwater]

I've had zero problems running with the 87 octane, maybe they could try reflashing the computer? Or maybe theres a bad sensor? In any case I wouldn't drive it to long before I new for sure that everything was ok.
I hope that they can figure this out for you.

[bighawaii]

Originally Posted by alw

Ok, we've discussed this before in other threads, but I wanted to see if anyone else has this too.

If I run 87 AKI (AKI is the rating at all gas pumps in the U.S. r+m/2) gas, my truck pings like crazy. Service guy says Nissan recommends 91 AKI or higher gas if you have pinging. He says the pinging I hear is the computer adjusting the timing to make up for the gas and that Nissan doed not really enforce the higher octane requirement.

I thought the Titan was speced to run 87 AKI gas!

what exactly is this pinging? is its knock, if so did you or your dealer actually measure it? i doubt you are getting any more then the rest of us. have you listend to another titan? it just may be your injectors or purge valve, they are both a bit loud. the titan is designed to run on 87 and doesnt need 91, if they actaully test your truck on both octanes and it goes away with the 91 then the problem lies with your computer like bestatchess said, and its inline components(sensors, wiring, etc).

[Steamguy]

Originally Posted by alw

Ok, we've discussed this before in other threads, but I wanted to see if anyone else has this too.

If I run 87 AKI (AKI is the rating at all gas pumps in the U.S. r+m/2) gas, my truck pings like crazy. Service guy says Nissan recommends 91 AKI or higher gas if you have pinging. He says the pinging I hear is the computer adjusting the timing to make up for the gas and that Nissan doed not really enforce the higher octane requirement.

I thought the Titan was speced to run 87 AKI gas!

alw,

It is. You have something wrong, and need to get into the dealer before you have engine damage.

On the other hand: If you have 1 (one) ping when charging up a hill, the knock sensor in the engine is doing its job. The system adjusts to load and fuel quality.

If you have continuous pinging, you have a preignition problem and need to get in NOW. This will wreck the engine in short order.

Don't believe any tech who says you should put 91 octane in it. I tow a trailer with 87 octane in the tank.

One thought though: you should not be buying fuel with excessive ethanol additive if you can help it. I forget the level of ethanol; see the manual.

Steamguy

[bighawaii]

Originally Posted by alw

Yes, this was after 5 tanks of gas from different stations. Should it take 5 tanks for the computer to adjust?

if you really know you are getting increased knock then no, it shouldnt take 5 tanks, it should adjust during or after the 1st tank of fresh gas.

[bighawaii]

Originally Posted by Steamguy

alw,

It is. You have something wrong, and need to get into the dealer before you have engine damage.

On the other hand: If you have 1 (one) ping when charging up a hill, the knock sensor in the engine is doing its job. The system adjusts to load and fuel quality.

If you have continuous pinging, you have a preignition problem and need to get in NOW. This will wreck the engine in short order.

Don't believe any tech who says you should put 91 octane in it. I tow a trailer with 87 octane in the tank.

One thought though: you should not be buying fuel with excessive ethanol additive if you can help it. I forget the level of ethanol; see the manual.

Steamguy

on the side note, preignition can be one of many causes for continuous pinging.

[alw]

Does the purge valve make noise in time with the engine rpm?

The noise I am hearing only happens when the truck in under load i.e. in gear, driving and accelerating. It does not happen while in park.

[bighawaii]

if you hear it under load and not when parked or stopped then its not your purge valve. when exactly did you notice the ticking start? if its a soft ticking then its probably your injectors though i personally cant hear them, i have yet to drive with my windows up listening closly for odd sounds. if its very loud or sounds like metal hitting on metal then i would take it into the dealer ASAP like Steamguy said. matter of fact, i would take it into the dealer and take a drive with the service man to replicate the sound.

[cali-titan]

Originally Posted by alw

Does the purge valve make noise in time with the engine rpm?

The noise I am hearing only happens when the truck in under load i.e. in gear, driving and accelerating. It does not happen while in park.

Alw, I hope your O2 sensor is not damaged by now, but I would advise:
1) Take the truck for a long drive at high speed, no stop and go traffic, this will help clean the cylinders and any residues in the ALL IMPORTANT O2 sensor, drving too slow in stop and go traffic can/may ruin the cumbustion chamber... with this I mean, red line it once in a while it is not so bad, in fact it is good for the engine.

2) Use a quality gas.. a name brand, in other words use Regular Mobil one, yes it is two cents more, but you will not have problems regarding ignition issues, pinging, cat converter failure, etc.

3) If in traffic take the overdrive off, sometimes you will find that if you keep the foot in the same place, but downshift one gear (or two) you will go faster, even when you are not pushing the gas anymore than before manually-shifting .. I hope that made sense.

Well, good luck and I hope it helps... lets us know how it went.

[Steve04SE]

Originally Posted by alw

Does the purge valve make noise in time with the engine rpm?

The noise I am hearing only happens when the truck in under load i.e. in gear, driving and accelerating. It does not happen while in park.

Are you hearing a "slight" pinging upon initial acceleration which goes away when you reach desired speed, a clattering (louder than pinging), or a knocking (louder than clattering). Do you hear it when going W.O.T. (floorboarding the throttle) or only upon initiating gradual acceleration and upon backing off throttle, after reaching desired speed, it goes away.

Slight pinging under acceleration (not WOT) is called "tip-in knock" and is NOT harmful to engines according the Titan owner's manual (and Corvette service manual). This "slight pinging" indicates the engine is properly tuned for optimum performance.
Again, I'm referring to "slight" pinging when initially depressing gas pedal which quickly goes away as speed increases. When going WOT if pinging, or worse, clattering or knocking occurs, you definitely have a problem.

[alw]

What I thought was pinging has since diminshed greatly, if not gone away.

I have tried for weeks to locate the source of it. Driving with the windows down, I could not hear it from outside the cab. With all the windows up, I could hear it over the radio and a/c at a normal volume. It did happen with throttle lead in and under WOT.

It has been frustrating as it comes and goes. I have taken a length of 1.5" pvc pipe and poked around the engine for clues. Nothing coming from the valve covers, cannot locate an exhaust leak. The only item that sounds remotely possible is the fuel injectors.

Anyone know if it's possible for one or more injectors to make noise on an irregular basis?

[stevemis]

Originally Posted by Steve04SE

Slight pinging under acceleration (not WOT) is called "tip-in knock" and is NOT harmful to engines according the Titan owner's manual (and Corvette service manual). This "slight pinging" indicates the engine is properly tuned for optimum performance.

I believe it was GM who called that "the sound of economy" back in the 70's or 80's. It tends to stop when you bore a hole all the way through the piston.



-Steve

[alw]

Whatever the noise is (purge valve, injectors, crappy gas), it's back.

I guess the dealer will finally take action and get off their rear when this damn thing finally blows up. 5 years and 60K, here I come.