I just filled my tank with Stop & shop 87 octane gas, and shortly after I noticed a strange sound comming from my vehicle. While traveling at a speed of over 35, if I take my foot off of the accelerator, and then give it a little gas to accelerate, I hear what sounds to be what I can only describe as an obnoxious air sucking/metalic swoosh for a brief moment before the vehicle begins to go faster. I can also feel this noise slightly when it happens.
This was not happening before I went to the gas station. Could it be the gas, or something completely unrelated?

 

Harry, first off, if you filled your tank with 87 octane gas, that can be part of your problem. Our motors are supposed to be using 93 octane gas. Running the lower grade gas can lead to engine pinging, which may be what you are hearing. Going with more of a brand name station, they tend to use higher than stated octane gas, which allows some people to get away with using less than 93 octane pumps.

Other than that, not sure what you could be hearing. Did the intake fall off of the motor? Just a silly question to ask. I would also do a hose check and see if you have a hose that suddenly failed on you and it just happened to occur around the time you filled up.

 

Hello,

Is it pinging, which sounds like marbles rattling in a can? If so, either the fuel octane is too low and / or the engine's knock sensors aren't working. The X-Type has two knock sensors located on the block beneath the intake manifold and it's a fairly big job to replace them.

Is the check engine light on and are there any codes stored?

Good luck,

Steve

 

Sounds very much like marbles in a can. No check engine light. It also doesn't do it at a dead stop. only at cruising speed under load.

 

One more thing, could I possible correct this by using some sort of octane booster?

 

Hello,

Hope that it's just fuel with too low octane. Pinging (knocking) isn't good for the engine: it's actually the sound of the pistons trying to reverse their direction which is caused by the fuel detonating before the pistons are at the top of their stroke. It puts a lot of pressure on the piston's wrist pins and connecting rods.

If you have a full tank, buy an octane booster additive at your local auto parts store (I think 104 Plus is one brand) and add it to your tank as soon as you can. Otherwise, add the highest octane fuel you can find. If the sound goes away it's entirely fuel octane-related. If it doesn't have the knock sensors checked.

Good luck,

Steve

 

I have added prestone octane booster to the fuel and drove about 5 miles which has definately helped.
Shouldn't pinging such as this trigger the check engine light to come on?

 

how would it if your knock sensors are faulty ? The knock sensors should retard the timing enough for you to safely run any gasoline octane, that makes me think they are bad.

Please use only 91 octane or higher, preferbly from shell. The jag isnt for reg unleaded so using it , or thinking its fine is wrong. While Im sure you thought nothing of it, steer clear of it. Do as the manual says, only add the minimal amount of fuel with lower then 91oct rating to get you to a station that carries 91 octane.

If its not avail where you are, get the knock sensors replaced or sell the car.

-vic

 

Hello,

Not sure if the CEL could be triggered by low octane.

As you burn fuel in the tank keep adding higher octane fuel - this will help increase the average octane value.

Be sure the car isn't overheating which can also cause premature detonation / pinging. Don't just look at the temp gauge, be sure the reservoir is topped-up and that there aren't any leaks. Has the car overheated at all recently? If so, you may have damaged a head gasket.

I think increasing octane should fix it. But, if the symptoms don't completely go away have the knock sensors checked.

Good luck,

Steve

 

There definately has been an improvement after adding the octane booster, however octane booster will only bring the octaine up by a single point, so today after I drive to and from work I'll add a gallon or two of 93 octane. I'll do this until it completely stops.

 

Id run the tank to around a quarter before you add new fuel. Add more booster instead.

You dont want to keep the 87 blend in there for longer than that tank, which you will by diluting the fuel with 93 octane. Just go on a drive to waste some fuel and top up once your nearing a quarter tank.

 

If your car won't run ping free on regular octane gas, their is an underlying problem that needs to be fixed. The knock sensors will automatically back off the timing to compensate, with an accompanying loss of power. Makes no difference if you're cruising at a steady speed or are generally light on the throttle.

Note that the typical octane boosters only increase rating by .1% per can not 1%.

 

My issue is that I'm not sure if what I'm hearing is actually pinging. To a layman such as myself it sounds like air sucking for a half a second. Also, the conditions which create the noise have to be specific. If I go from a dead stop to 70mph the car runs great regardless how gentle or harsh I step on the gas. The only time I hear this noise is when I'm coasting at around 40mph, with my foot off of the petal. Then if I give it a small romp I hear it, as if something was either engaging, or again, the sound of "air" swooshing. It does not make this noise at any other time.

If this was truely pre-ignition wouldn't it happen say on a hill or during regular driving?

 

Correct. It would happen any time there was a heavy load on the engine - accelerating or climbing a hill. Sounds like you have something else going on.

 

Harry

Hopefully it just that simple and you're good to go.

 

A/C compressor clutch?

 

Hesitations can ne caused from many different things.

Allow the fuel to run out, and replace with new fresh 91 or higher octane to eliminate that variable. Of course if its the fuel it wont go away as you pull away from the gas station. That new fuel will have to make its way to the motor.

If the problem remains you have to go to the next step, which the pros will inform you on.

 

i didthe math on the octane boosters.. you would need to add several cans of it to raise your octane lever by a point.. they write on the side of it you raise your octane by a point.. they mean 0.1 octane.. I learned this running a race rotary engine and needing 94 octane minimum for my computer settings i nearly blew my engine when only being able to put in 91 octane.. i had to put in 6 of those cans to get my engine to run right with only 15 dollars of fuel

 

Maybe you can help me since I think my problem is fuel. I have a 2002 X-type 2.5 sport model 70,000 miles. It looses power (sometimes) at 2800 rpm. I can run fine under 2800, but cannot go above until the problem clears 30 seconds to 3 minutes. When it clears the car has real get up and go like it should through out tac range. Engine light is on and the code reads Lean. I have replaced the fuel filter twice and am running 93 Octane. Could have got bad fuel. Fuel does have Ethonol less than 10%. Currently running Shell with 31 MPG highway. I have added additives to remove water in fuel as a solution. Any other ideas. The problem is intermitant. Recently drove 700 miles with no problem. Other times the problem can happen within 10-30 miles. Shutting engine off does not clear the problem. It acts and feels like a clogged fuel filter except it always happens at the same RPM.

 

It's not the fuel and you won't find a cure in a bottle of miracle fluid.