Knocking and Pinging problem with me pickup truck

[dan2957]

Any mechanics out there?

I have a 1995 F150 that has been knocking and pinging when I am under load pulling my boat. It does not seem to do it all the time but it is getting more frequent. If I slowly accelerate it does not do it as much as when I gun the engine. I have changed the PCV valve, ignition coil and wire, and have a new distributor cap. I also put a timing light on the engine and the timing is within specs.

What else should I look at to solve the problem? A guy at work said I should not worry about it because all trucks knock a little, is this true? What could happen to the engine if I just leave it alone and let it knock?

[Gissert]

Have you checked any of the fault codes? Many places will pull the codes with a scan tool for a fee, and that may tell you exactly what is wrong, ie MAF, MAP, oxygen sensor, etc.

[BobT]

Considering it's about 11 years old and probably has many miles, it is quite possible the engine is starting to get tired. I'm not a mechanic by trade but I am by age and in my experience pinging is typically caused by early ignition. Since the engine is getting tired and perhaps losing compression, it may not be responding to ignition the way it once did, especially under load. In older vehicles (pre EFI), switching to higher octane fuel usually helped. The way I understood it, higher octane fuel is slightly less explosive so by using it you retard your timing just a bit because it takes just a little longer for the fuel to ignite.

I don't know, but could your mechanic check engine timing first to be sure it isn't too far advanced and second, perhaps it could be retarded a degree or so to compensate.

Bob

[Wishin2BFishin]

Knocking can cause damage to the pistons if you don't correct this soon. Can burn holes in the tops of them. Knocking is caused from the timing too far advanced or poor fuel octane or from the engine running too lean. If your using regular fuel (87 octane) then you will need to start using 90 or higher or use an octane booster in the tank. You can try backing off the timing as well. Have you replaced the oxygen (02) sensor recently? This monitors the exhaust and adjusts the fuel mixture. It may be sending the truck's computer the wrong information and could be the cause of the lean burn condition. Also a vacuum leak from one or more of the many hoses attached to the engine could be the cause of this. I have a way of finding any leak. It's not the safest way to do this so be VERY CAREFUL!!! If you have the engine idleing take a can of starting fluid and (lightly) spray each hose. If the engine revs up a little while spraying a hose then it's leaking. Again be very careful!!!

Best of luck...

[Jeremy airjer W]

Do these have the EGR ports behind the thrattle body? What if they where plugged. EGR helps reduce combustion chamber temps which helps reduce ping. The newer fords have a DPFE sensor that can monitor the flow of EGR. The older fords had an EGR pintle sensor that monitored how far open or closed the sensor was. With the engine running remove the vacuumm hose from the EGR vavle. Using a vacuum pump apply vacuum to the valv. If the vehicle stalls ignore everything I just said. If it doesn't stall I would suspect plugged EGR ports may play a role in your ping issue. An upper end cleaning probably wouldn't hurt to try either.

[Valv]

Quote:

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...Using a vacuum pump apply vacuum to the valv.

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I don't think I am going to like any vacuum applied to me, no matter where you apply it....

Anyway, DO NOT spray ether over a running engine, if one of your spark plug wires has even a little crack you will not look very good for a long itme, this is dangerous, carb cleaner might be better, WD40 is great.