Pinging noise under slight acceleration

[Justin1985]

Just noticed today a pinging noise coming from the engine. I cannot reproduce the sound while stationary. Had my wife rev the engine and I can't hear anything unusual. I've filled up on premium gas, and checked the oil. I am having a bit of smoke from the dipstick tube and it was very low on oil. I just got this vehicle and the first 3 weeks it drove perfect. Best I can describe the noise is a jackhammer off in the distance. That's actually what I thought the noise was when I first heard it (going over a large bridge crossing the ocean). Its not very loud but I am concerned. It seemed to just start today and out of nowhere.

1996 Explorer V8 5.0 Eddie Bauer 156k miles.

I'm seriously about to buy a horse and buggy with all my troubles....

 

[Justin1985]

I've narrowed the noise down to about 1250 rpm. Any higher or lower and the noise ceases.

 

[Justin1985]

New symptoms... The noise only happens after the engine is good and heated up. Again, only happens while moving. If I keep my foot on the brake and while in gear, push on the gas, the sound doesn't happen. Any help would be great.

 

[gmanpaint]

Engine fuel Ping vs Engine spark Pre-detonation ping.

Ping can be caused from lack of fuel pressure under certain loads. I had this happen, and it turned out to be a weak fuel pump relay. This happens from heat and age. I have had to replace it a couple of times over the years, because the wiring leading to it, is also weakened by heat and age. It can also be caused by a weak fuel pump. Fuel pressure needs tested at different rpm's, and different loads.

Pre-Detonation can be caused by a bad ignition component such as the coil packs or the IGN module. There are other items besides these.

Point being, you need to determine which issue you have first. This can be a pain to figure out, just be patient, and do as much research here before replacing parts.

 

[Justin1985]

Thanks a lot. I had the fuel pump replaced about 3 weeks ago. My brother is a parts guy and he said Ford is notorious for low fuel pressure. I reckon it would be wise to replace the relay regardless. Its not going to hurt anything. Will update upon diagnosis.

 

[Turdle]

Detonation ping can be cause by non metered air entering the combustion chamber.

Make sure the pcv valve is making good seal. The grommet it slides into can go loose and leak vacuum. Also, the dual feed vacuum line for the PCV can get brittle and the F fitting can crack.

Double check the area around the vacuum brake booster one way valve. Move it around a little while the engine is idling and listen for leaking vacuum.



Have you cleaned the MAF sensor?

Check engine light turned on? Just to double check this, does the check engine light turn on with the key?

Does the HVAC switch from vent to defrost as it should? if not, this could indicate a vacuum leak.

 

[Justin1985]

The check engine light is not on while driving, turns on with the key, and hasn't come on since the issue started. Havent cleaned MAF but i think i need to as im missing some power. Vent switches to defrost fine but my AC compressor clutch wont engage (dif problem for a dif day). My brother said it could be worn rockers and as my oil heats up, it gets louder. Heat seems to be a major factor now. It's 90 out today and she's rattling away. I put in STP oil treatment which helped a little. I was told if it was a spark knock that it would throw a code. I have relegated myself to a new set of rockers but haven't committed yet. I read that the factory rockers were soft and one could be walking around.

 

[Flash]

If it's smoking from the dipstick tube then I'd say the MAF needs a clean.
Check the PCV as well.

You might have some carbon build up in the combustion chamber due to it sucking up oily air, you could probably benefit from a Seafoam clean.

The way I do it is with the engine good and warm I let the engine suck up about half the can then I let it really suck it up until it chokes on it.
This coats everything with Seafoam.

Leave it overnight or at least several hours then start her up and go for a highway drive.

It'll smoke like some sort of really bad smoking thing for a while.

It would help to stick some in the tank too.