ADKMustang

So I could use a little help. I store my 07 GT vert (33,000 miles) over the winter and when I brought him back to life he has a bit of spark knock mostly between 2-3 and 3-4 under heavy acceleration. What I have done to try and remedy is changed the fuel filter, disconnected battery for an hour to reset computer and tried higher octane gas but it is still making the knocking sound.

What should I try next...spark plugs?? What else....it didn't do this before storage. Any help would be appreciated. Thanks!



PS...I used stabilizer in a full tank before putting him to sleep.

edwin108

Do you have a tune?

ADKMustang

No tune and it is all stock.

edwin108

How much gas do you have left in the tank? I would siphon it out and fill up with fresh gas.

ADKMustang

When I took it out of storage I ran it down half way and then put in 93. Ran that empty then filled it up with 91, now that is down to 1/4 tank left. Before storage I had been running 87 no problems at all.

drewsky

I'm assuming you didn't put any gas treatment solvent over the winter? I would burn all the gas in it but taking it easy on the throttle and not much load at all!! Then run a combustion chamber/injector cleaner at the gas station the next time you fill up.. See if that helps at all.

ADKMustang

I certainly can try that. I did put Stabil in the tank before putting him to sleep for the winter so that fuel should have been OK for the spring.

Anyone have any thoughts on spark plugs? Should I do them at 33,000?

Simon1

I would run the car until it has zero miles left on the trip computer. The bad gas will absorb water and water stays at the bottom of the tank.

I got a batch of bad race gas one time and it took 3-4 complete fill ups before it was gone out of the tank.

I have a homemade insert I put into the fuel rail, start the motor and then turn a valve and the pumps pump out all of the fuel. Motor still runs will continue to run until there is no fuel left.

After the fuel is completely gone and a few tanks of fresh fuel has gone through the tank, then I would worry about throwing parts at it.

Next time you store it. Run it dry or almost empty and find fuel that has no ethanol in it. You can usually find this stuff at specialty places. They will usually be labeled as "off road".

ADKMustang

OK....so I have put in Valvoline Techron and 94 octane and run that down and the verdict is.....well mixed. The spark knock is a little better but under heavy acceleration (load) I am still getting knock.

What would be the next step......what should I try or check. Thoughts or advice....

Simon1

Run tank empty to 0 miles, fill up with the highest octane possible. Drive car. Re-access.

It's very rare for our cars to have spark knock unless there is an octane problem, tune problem or vacuum leak causing a miss.