Looking for your opinions. I have a 99 F-150 SC 4.6L Romeo engine, auto trans, and 3.55LS rear end. The truck has almost 28,000 miles on it.

When lightly accelerating, the engine pings sounds like octane knock. It will only do it after the engine is up to full operating temperature (30 Mins from a cold start). Runs great cold. It seems to be aggrevated by very hot days (I live in Tucson, +100 F temps). Really haven't noticed it on cool days, prior to this summer.

I've had the truck into Ford dealer three times. First time the service manager told me to run two full tanks of 89 octane. There was no change, still pinged like a banshee. Second time I took it in, they actually spent some time with it and replaced the MAF sensor (said it was out of range). This still has not fixed the problem though. Third time I took it in, the same guy that told me to run 89 octane said during a test drive with me, "a bit of light pinging is normal on a hot day, in city traffic". He said the computer doesn't have enough time to adjust the mixture (air to fuel, I suppose). He said to run 89 Octane it all the time.

I've tried the Chevron Techron treatment also, seemed to improve it a bit, but as soon as I put another tank of gas in (87 Octane-what's recommended) the problem returns.

Any of you all having similar problems? Does what this guy is telling me sound reasonable to you? My car doesn't do this, why should my truck?

Steve

 

Hi Steve,

Every once in awhile one of these vehicles will behave like this. Many times it's due to a bad MAF, as they looked into already in your case, or an EGR (exhaust gas recirculation) issue, etc.

And then sometimes it's just a matter of needing to use a better quality fuel, a gas with a higher energy content. I don't know what brand of gas you're using, but usually Texaco & Amoco have good high energy content, and there are some other brands that can work well too, but those 2 brands are generally among the best in most areas of the country. Steer clear of Exxon (low energy) and any off-brands or no-names, as they will generally have lower energy content, and that can contribute to detonation even if the octane number is there. Some areas do have fuel quality issues, as some areas have poor air quality, and that is generally where you'll find the worst fuels in terms of their energy content, in areas of poor air quality, thanks to the Feds air quality monitoring campaign. Again, I have no idea if this affects you in your particular area.

That vehicle should *never* exhibit detonation on a good quality 89 octane gasoline on the factory program. It really shouldn't do it on good quality 87 octane either, but once in awhile we'll see one of these trucks that just needs to have a good 89 octane in the tank, and nothing less will do, either due to just a quirk with an individual vehicle, or due to overall poor quality fuel in a particular geographic area. Not often, but it happens on occasion, even though they are actually tuned for 87 octane from the factory.

If this continues to happen on good quality 89 octane, and your dealership says they can't do anything aobut it, then in that situation I would ask your Service Manager for the name & number of their Zone Rep. (each Ford dealership has a factory Zone Representative), who can make an appointment to come out and meet you at the dealership and go over your concerns.

However, if using a good quality 89 octane clears this up, then you'll probably just have to bite the bullet and use it all the time, as Ford cannot control fuel quality, of course, that is something beyond our control as layman, other than to just use what we feel are the best fuels available in our area.

The basics to check when detonation occurs are, use good quality gas, then check things like the MAF (already done in your case), EGR functions, O2 sensors, etc.

Sorry I can't be more help, good luck & do let us know what develops!

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
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[This message has been edited by Superchips_Distributor (edited 06-30-2001).]

 

Try what I outlined, since it doesn't cost much, you don'y have a lot to loose.

pinging fix

 

Thanks for the inputs. I'll give this a try. I failed to mention in the first post that I use Chevron gas and that this pinging only happens at very light acceleration. No pinging at full throttle.

What sensors are outside air temperature related? As I said before, there is also no pinging when the temperature is below 90 degrees F.

Thanks for the link Ted, I'll definately check that out.

Steve

 

The way you desribed this tuning is the way I learnt to tune engines--Give the engine as much timing as it can handle..For maximum performance and maximum fuel mileage....The engine should not ping under hard acceleration but will ping very lightly under no-load....

If this pinging can't be corrected by the grade of grade then the engine can be detuned by retarding the timing..

The way it is setup is the way I like to run my vehicles...these engines are less suseptible to engine damage due to a little pinging....everything in the valve train is hardend because of the no lead....

Now I said that it is normal to have a very light pinging...not any heavy or any dentonation....

You will get maximum performance this way.....

I also agree that a good quality of fuel should be used in all cases
and that on hot days the engine is more suseptible to pinging...

which brings up another possibility....in stop and go traffic when the engine temp is higher the engine will ping more....

I would check things like driving habits, engine temp, fuel quality...

If it is heat related then on a cool day it probably will not ping, here again the way I prefer to have my engines tuned...

Light, light ping on the highway no load summer heat...no ping under hard acceleration....