Can old gas cause detonation or pinging?

[04silversnake]

Hello all, I just intalled the tune I received from James today to go with my 2.93" BF. First let me say I had the car sitting in the garage for two weeks with 1/4 of gas of tank. When I took it for a test, I noticed it was pinging between 1500 to 2500 rpm. This happened on a little boost, 5-8 lbs. I was not flooring the car. When I drove it hard, and shifted at higher RPM, I did not hear any pinging. I then, inmediatly fill up fresh 93 mobil. I drove the car a few miles to waste the old gas from the line. Then i attempted to duplicate the same pinging, noticed it almost was gone, but you could hear very little pinging. Taking it to the dyno this week. Any sugestion? I will also speak to James for any suggestion he may recomend. Do you thing the gas sitting in the tank for 2 weeks could have caused this?

 

[LargeOrangeFont]

Yes. More likely was that is was some "bad" gas (not necessarily old). I try to stick to a certain brand, (76 personally) and even from the same station whenever possible. I've gotten a couple bad tanks when I had my WRX, filled up w\ fresh gas, reset the ECU and all was well again.


Ashley

 

[04silversnake]

Will it be necessary to change the tune slightly? like, less timing, or should I have it dyno first? It still pinged very little.

 

[OZ Dude]

Gas does have a definite shelf life but it's usually longer than 2 weeks. Having said that, you don't know how long it was sitting in the gas station's tank for. When you filled up with the "old gas" it could have also been from a near empty tank and dragged up some water, etc. Could of also just been a bit of a bad batch.

As long as it's gone now - that's all that matters!

 

[LargeOrangeFont]

Try resetting your ECU.

Pull negative battery cable, pump the brake a few times and reattach it.

Go out and drive it hard and see if the knock comes back. If it does, dial back a degree of timing and see if that helps.

EDIT: Don't drive it hard until you get the a\f checked.

 

[04silversnake]

LargeOrangeFont, I try always to put BP from the same station since its convinient for me.
OZ Dude Yes, who knos if the tank was almost emty at the station, so that means is even older than the 2 weeks I had it

 

[LargeOrangeFont]

LargeOrangeFont, I try always to put BP from the same station since its convinient for me.
OZ Dude Yes, who knos if the tank was almost emty at the station, so that means is even older than the 2 weeks I had it

Thats good, getting some bad gas happens to all of us at one time or another. You just notice it more on a tuned\modified forced induction car.

The nature of your ping sounds a little odd. What gear were you in when you got the pinging at that low of RPM?

As I said, I wouldnt beat on it till you get it checked out on the dyno.


Ashley

 

[04silversnake]

I donk know if it will affect anything but will try it anyways. I was told that when the new tune is first put in the car, it resets the computer.
Will dyno this week also to make sure everything is ok.
BTW, i did a search and saw an old thread where someone asked if detonation can be identified from a dyno. They said yes it can, and showed a dyno link, but since the thread is so old, I could not open it. Can someone post one of this, so I will know what to look for.
thanks for all your replies.

Try resetting your ECU.

Pull negative battery cable, pump the brake a few times and reattach it.

Go out and drive it hard and see if the knock comes back. If it does, dial back a degree of timing and see if that helps.

EDIT: Don't drive it hard until you get the a\f checked.

 

[04silversnake]

It was noticeable in that RPM range 1500-2500 at 2nd, 3rd, and 4th. Didn not hear it at higher RPM. May be because the CAI and the CB why it was harder to hear. Not noticeable at least.

 

[LargeOrangeFont]

If you car is catless you can see it ping on the dyno. A black puff of smoke will come out of the tailpipes. If you have cats this may be harder to see.

The car will "learn" as you drive it. If it pings, the ECU will remember the load site and try to correct for it, next time it passes through that load site.

Resetting helps the ECU to start from scratch from the baseline tables, and the ping may dissapear completely.

Ashley

 

[04silversnake]

Will reset it. Do you know for how long? just press the brakes is enough with the batt negative disconected?

If you car is catless you can see it ping on the dyno. A black puff of smoke will come out of the tailpipes. If you have cats this may be harder to see.

The car will "learn" as you drive it. If it pings, the ECU will remember the load site and try to correct for it, next time it passes through that load site.

Resetting helps the ECU to start from scratch from the baseline tables, and the ping may dissapear completely.

Ashley

 

[04silversnake]

Yes, I have the stock H pipe.

 

[LargeOrangeFont]

Pump it like 5 -10 times... should be enough. On some cars there is a capacitor to hold power to the ECU if power is lost for a second or two. Pumping the brake supposedly will get rid of any charge left in the system.


Ashley

 

[04silversnake]

Thanks for yout tip LargeOrangeFont.
By the way, I have to say like many others members have, good comments about James RWTD. I sent him a reply about my concern and he replied to me with suggestion and provided me a revised tune for the bad batch of gas. This is a great tuner that takes good care of his customers. Highly recomended.

Pump it like 5 -10 times... should be enough. On some cars there is a capacitor to hold power to the ECU if power is lost for a second or two. Pumping the brake supposedly will get rid of any charge left in the system.


Ashley