Alright my 1996 F-150 351 has got a pinging problem.

I am running 91 octane, (I tried the hypertech programmer so I put in 91.)

and recently did a coolant flush on it at a local lube shop. so basically the engine will ping at highway speeds in 3rd and 4th gear.

I took the programmer out but this seemed to happen after the coolant flush was done.

what are some things I could check?

-plugs are my guess?

 

Check your base timing with the spout out , it should be 10 degress BTDC ...Lew

 

Your engine (stock) is engineered to run on 87 octane. It lacks the compression rate to successfully digest 91 octane as a regular diet. Seafoam, 1/3 can through the power brake booster Vac hose, while the engine is at warm idle. Shut off for 15 minutes. Pour the rest into the gas tank. Restart & rev out the combustion chamber contamination. Then take it for a hard drive. There will be an incredible amount of white smoke for a minute or two. My 302 runs fine w/ my base timing set at 16 BTDC w/ 87 octane. If you start running higher octane, eventually it will require the higher octane just to run w/o ping. And then higher octane till you run out of higher grades. It phenomena is called fuel wicking. Incompletely ignited fuel soaks into deposits, causing uncontrolled detonation. I would also switch to Motorcraft Nic plated copper Core plugs at least until the condition is rectified because Double Platinum plugs can & may burn a hole it a piston & are less likely to cause ping. You may need to repeat the Seafoam process after a tank of gas.

 

thank you both for the insight. I am gonna put the programmer back in and then run the tanks dry and switch back to 87 and take the programmer out.

then just set my timing to I think 14 degrees BTDC.

 

If you want to run 14* you will need 93 octane.

 

Or whatever it will tolerate with the combustion chamber deposits. What it will tolerate will be a direct indication of the amount of deposits. I've seen engines so carboned up, they couldn't handle 10 BTDC! Remember base time is w/ the spout plug removed. Don't forget to replace the plug after base time is set or you will have no ECU timing advance!
Seafoam will speed up rectification of this problem, but I would refrain from adding it to your oil, unless your planning on changing your oil soon. Stick to just the combustion chamber & as a gas treatment. I treat mine just prior to each oil change. Once every 8K (I use synthetic oil). The high octane gas would actually be better for running Seafoam added, as it will allow better saturation of the deposits while running. I've seen this situation many times & the Seafoam method is the cheapest, easiest & quickest method of dealing w/ it. You can also have it done "professionally" but it runs about $175-225, depending where you go.

 

If you have heavy combustion chamber deposits. & if you run 93 octane, you will have those deposits.
My 87' 302 runs 87 octane at 16 BTDC w/ motorcraft Nic Plated copper Cores w/ no problem. I can run 18, but the slight performance increase doesn't justify it the extra 2 degrees.

 

well I went out tonight (I did nothing but work and had no time for my baby )

and installed the hypertech programmer everything worked great no pinging nothin. on the front tank....

when I first started the truck it was on the rear tank and it started up then idled down and died... started again it idled up and then died again.... so I gave it a little gas and it didnt rev up at all. it had no power so I put it in drive and hammered it and it moved but then there was no power (like pushing the pedal and nothing happens and then it drove fine after those few hick ups. the truck felt under powered and so I switched to the front take and it ran smoother idled nicer and had more power on the front tank than the rear.

my understanding is that there is 2 fuel pumps 1 in each tank. the previous owner said he never ran the rear tank when he bought it so he didnt even know if it worked. my guess is.... I have a bad rear tank fuel pump

so the plan is to run the 91 till empty then fill up with 87 and take the programmer out. people have told me to use the v-power that shell has as it helps clean valves. and I am gonna pick up a can of the sea foam from napa tomorrow.

 

Dosen't explain the miss running on the front tank. It's nice tohave the second tank for trips. Your going to have fun with the Seafoam if you actually use use it. As I mentioned, skip adding it to your oil unless your planning on changing it soon. 1/3 through brake booster Vac hose at warm idle, off for 15 mins. 2/3 in tank. Restart and rev out the funky crap. Take it for a hard drive. Then Lucas Injector cleaner, every 5th tank, as maintenance. Seafoam has been used for this purpose for over 30 yrs.