'90 F150, 302, 150k mi

I have some nasty pinging that I haven't been able to get rid of. I've done a tune-up (new plugs, wires, cap, rotor) but it didn't really have any effect. I haven't checked the timing (I don't have a light), but I have no reason to believe the timing is advanced too far. On 87 octane, it pings like a *****. On 89 octane, it pings pulling hills on the interstate. 93 octane - I can't afford that in this gas-hog - LOL!

Anyhoo, on to the question; I've read here that I should give the EGR system a look - that a clogged/dirty EGR system can cause pinging. Umm, where is the EGR and how should I clean it? Is it the big nasty, rust-colored thing off the left side of the throttle body? How should I check to see that the EGR valve itself is still functioning properly?

Wade

 

PKRWD once told us if you seperate the last 2 plug wires on the drivers side and keep them seperated throughout their entire routing alot of the ping will disappear. These 2 wires are one after the other in the firing order and keeping these seperated will prevent crossfiring, or pre-ignition, which is ping. It eliminated my ping 99.99%. I was one happy camper when that was gone. I was able to pass slow cars again. Give it a shot. Use some tip-ties if necessary.

The EGR is just downstream of the throttle body. Use brake/throttle cleaner. In my experience with cars the EGR hardly ever causes ping, usually causes stalling and stumbling, bad mpg, and check engine lights. But I don't work on F150s, I work on gm crap.
Good Luck and let us know!

 

Thanks inski21! - I'll take a look at that (along with the EGR ) during my time off from now 'til 1-6-03. I will report back what effect it had.

Wade

 

Most often pinging is caused by too much ignition timing advance, but it can be caused by a lean air/fuel mix, high intake air temps, overheating engine, carbon in the combustion chamber, or the EGR system. If the EGR valve sticks open you will have problems with stalling at low rpms but if it sticks closed it can cause pinging. Most of the time an EGR problem will turn on the check engine light. The EGR valve looks kindof like a UFO it's near the throttle body, there will be a small exhaust pipe that goes up to it. There is a small air filter on the top of the vacuum modulator (next to the valve) that can be cleaned but my experiance is that it doesn't help much. Sometimes that exhaust pipe (EGR tube) gets clogged with carbon and all you have to do is take the tube off and clean it or take off the valve and run the engine to blow the crap out. It's hard to take it off of an old rusty engine though. Also, with the engine idling you can apply vacuum to the port on the top of the valve. If the valve is working it will open and the engine will run real rough or stall. I would check the timing first though. Then the EGR, then run some intake valve cleaner through it to get rid of carbon deposits.

-Jon

 

Jon,

Excellent post. Sometimes it's easy to overlook all possiblities and focus on one.

Another check would be to pull a couple plugs. Excess gaps from wear or simply over gapping means more voltage required to create a spark. Big gaps combined with wearing ignition components and plug wires, and possibly some fouling and wear on the plugs could also create a ping.

I also agree that if the truck has a decent idle, I would move the EGR system way down on the list of possible culprits. My wifes car had a sticking EGR and it ran great if you kept your foot in the gas some, but it wouldn't idle for crap.

 

Thanks guys - The truck idles smooth as silk. I just replaced plugs and wires a couple of months back. I guess I should focus on the carbon and timing more than EGR. That, and the plug wire routing.

Wade