2002 XLS 4 liter pinging

[thammel]

I bought a used '02 xls with 4 liter v6 last Sept. It has 52k miles now. The engine pings (knocks) frequently under load - mild acceleration. When in for another problem recently I asked the technician and he said there's no knock sensor on these vehicles now and that the computer takes care of this. How in the world then is timing controlled - with no into-knock sensor, I don't see how to stop this pinging. Any suggestions? Just live with it? I'm concerned over valve train (and other ) components. I've read re carbon build-up contributing to this, but am skeptical. Comments?

Thanks!
Tom

 

[TPLYNCH]

Try cleaning the Mass Air Sensor (MAS) then reset the computer. If no change, try seafoaming the carbon out.

http://www.explorerforum.com/forums/showthread.php?threadid=56770&perpage=25&pagenumber=1

 

[Eneurb]

When does the ping occur?? Around 2000 RPM under load perhaps??

 

[Doug904]

I bought a used '02 xls with 4 liter v6 last Sept. It has 52k miles now. The engine pings (knocks) frequently under load - mild acceleration. When in for another problem recently I asked the technician and he said there's no knock sensor on these vehicles now and that the computer takes care of this. How in the world then is timing controlled - with no into-knock sensor, I don't see how to stop this pinging. Any suggestions? Just live with it? I'm concerned over valve train (and other ) components. I've read re carbon build-up contributing to this, but am skeptical. Comments?

Thanks!
Tom

That mechanis is wrong, there have been knock sensors on the SOHC's since the first in 97'. They still have them even in 04'. They are in the valley of the engine where the lifters used to be, they are a round sensor with a single bolt in the middle of them. The connector is at the front of the engine beside the valve cover on the driver's side.

The knock sensor values for light loads,where you probably getting the pinging, is very little, maybe 2-3 degree's of retart. What the Tech should have offered you, atleast if you're still in warrenty, is a reprogramming of the PCM with a newer and better file for your vehice and this concern. They're out there but it takes five minutes to look so most just give some BS responses.

Do the before mentioned items, cleaning the MAF and checking your Air filter while your there. Also with your milage you need to check your spark plugs and the gap.

Later Doug.

 

[thammel]

Thanks for all the advice! I will clean the MAF sensor. I couldn't believe there was no knock sensor, so I'm glad to hear there is one. As for the knock, yes, I'm pretty sure it's under light load and in the 2k rpm range. The plugs are pretty new as well as the air filter. The PCM was reprogrammed recently also. I was having problems that I think now are the 4Wd auto system kicking in under hard acceleration up hills occasionally. The feel is kinda like a clunking feel. They worked on the engine, thinking it was missing, but I don't think this was the problem. I just got the car last Sept and it's a great vehicle. (2002 xls 4wd)

My latest project/challenge with it is to figure out how to turn on/activate the ambient temperature sensor. I harness is there (at the radiator) and I bought the sensor and plugges it in, hoping to get the exterior temp readout in the dash, but it didn't click on. Any ideas?

Thanks,
Tom

 

[Jack03EB]

You also might be concerned about carbon build-up. When carbon builds on your head and piston dome it increases compression ratio ie: say your stock engine runs a 10:1 comp. ratio, that's fine for reg. gas.The pinging is from detonation (almost like a diesel engine runs)The higher the compression ratio the higher the octane drag cars can run a 7.5:1 ratio, hence the fuel alcohol mix.
My best remedy for carbon build-up is a nice freeway roadtrip at varying speeds and/or
I will stick with my "pour" mechanic remedy Sea Foam engine treatment. If you haven't ever heard of it before it is the best!!!! Put it in your tank for a fuel cleaning or suck it up thru the PCV and choke the engine out, let it soak for 5 mins, then watch the smoke screen and listen how smooth your X will idle!!!

Also mainly if you do have a serious carbon problem your vehicle will diesel after shut-down. This is caused by hot carbon in the combustion chamber igniting unused fuel.

 

[eggbutt]

inform us what works, i have the same problem