pinging 3.8 in T&C '97 w/ 220,000 miles

[sheldon!]

I've got ping like I've never seen on any other car.

She has new plugs, (the good ones), a new upstream O2 sensor and great gas milage. No smoke or any visiable indication anything is wrong.

I've tried preimum gas and it does make some slight improvement, but still pings like crazy. I'd accept it on accleration, but she pings even at crusing with no load. Push lightly on the gas at any time and you hear some real clatter.

Before I hand over my credit card to the dealer, anyone have an idea?

[neon_rt]

I'm thinking knock sensor.
The knock sensor should be preventing knock, unless the knock is so severe that even though the sensor is telling the ECM that the engine is knocking, the ECM is to the limit on countermeasures to prevent knock.
If the sensor is not working at all, maybe the ECM is advancing the timing to increase mileage and is not getting a response that knock has occured.
It could be a leaking headgasket, it could be EGR, it could be ... the list goes on and on.
When you find out, could you please post it. Most people get it fixed and then don't tell us what it was. It would help to know if we are right or wrong (so we don't give other people bad advice).

[RahX]

i would have a shop check it out. it could also be carbon buildup on the pistons. 220k is a lot of mileage.

[holdemjunkie]

I think neon's right about the EGR, if its gummed up with carbon, making it so it's inop it will cause pre ignition (pinging). Make sure ur using the right octan gas, u will find the octan rating in ur owners manual. Somtimes ppl will use super gas thinking that there engine will run beter, but that not the case, super gas actuly burns slower then reg, so somtimes when ppl use super gas when they don't need to it will also cause pre ignition

[holdemjunkie]

I think neon's right about the EGR, if its gummed up with carbon, making it so it's inop it will cause pre ignition (pinging). Make sure ur using the right octan gas, u will find the octan rating in ur owners manual. Somtimes ppl will use super gas thinking that there engine will run beter, but that not the case, super gas actuly burns slower then reg, so somtimes when ppl use super gas when they don't need to it will also cause pre ignition

[sheldon!]

Thank you, all for the help!

I got a price of $89 for the knock sensor from the dealer. Geeze, he beat almost all the Internet prices. I'll look for the EGR tomorrow. Fallback is an appointment with the dealer next week.

I used the premium gas to see if it had any effect. Regular really was so bad it scared me. Thought the pistons would vibrate into pieces. BTW, I have a very light foot, and gas mileage is usually 32 ~34 mpg at 65 mph on the interstate. I have used 5w 30 oil since new, although for this problem I tried 10w 40. It made no difference.

I usually drove my Town Cars 250,000 miles before selling them. I was hoping to do the same with this vehicle.

Please continue to add anything else you think of as a probable cause.

And, THANKS AGAIN!

[RahX]

Originally Posted by holdemjunkie

I think neon's right about the EGR, if its gummed up with carbon, making it so it's inop it will cause pre ignition (pinging). Make sure ur using the right octan gas, u will find the octan rating in ur owners manual. Somtimes ppl will use super gas thinking that there engine will run beter, but that not the case, super gas actuly burns slower then reg, so somtimes when ppl use super gas when they don't need to it will also cause pre ignition

octane is an anti-knock rating. using a higher octane gas should diminish pre-ignition. ive never heard of higher octane causing pre-ignition, that just goes against its purpose. if the knock sensor is doing its job then the engine shouldnt have any detonation at all. using a higher octane will allow the timing to be more advanced but the knock sensor would keep it from being over-advanced.

[Stevo2]

Originally Posted by sheldon!

I've got ping like I've never seen on any other car.

She has new plugs, (the good ones), a new upstream O2 sensor and great gas milage. No smoke or any visiable indication anything is wrong.

I've tried preimum gas and it does make some slight improvement, but still pings like crazy. I'd accept it on accleration, but she pings even at crusing with no load. Push lightly on the gas at any time and you hear some real clatter.

Before I hand over my credit card to the dealer, anyone have an idea?

Try running a can of Mopar Combustion Chamber Cleaner(from Dealer) part# 4318001 or a can of SeaFoam through the engine and gas tank. Follow directions on the can or below. You can get the SeaFoam from NAPA/CarQuest for about $6. You could have a buildup of carbon in the combustion chambers causing your knock.
www.seafoamsales.com

Try this link for some info on how best to soak the engine. Scroll down til you see Mopar Combustion Cleaner. I would recommend that after you do this procedure that you change the oil and filter, so schedule both things when you need to change the oil.
www.allpar.com/fix/throttlebodycleaning.html

[sheldon!]

I have decided to follow the cheapest path to success. I have added injector cleaner with this tankful. The Combustion Chamber Cleaner will come next. Then, knock sensor.... then dealer.

I also noticed a few more things: ping only happens when the engine becomes warm and I hadn't changed the PCV valve since mile 1!

As I complete each step, I'll check here for any further notes from you before moving on to the next step.

Thanks, again!

[kuujak]

Check fuel pump pressure in road test. If not within specs put a new one in, the real thing, not a jobber's. This is what I did and it solved the ping knock problem.