[hphan1229]

I bought a used 01 Trooper in 2002 and it made some rattle noise in the engine when I am going up the hill. Took it to the dealer shop and they suggested to replace the fuel filter so I did that but the problem did not go away. So I took it back to the shop, then I was told that they did not find any problem so they told me to use higher octane gas. After that I used the middle grade gas, the noise is reduced a little but still a problem. Does any one have the same problem?

 

[TroopTad]

spark knock.

Happened on my ole 3.2

I'm guessing you have the 3.5, so I'll just go ahead and recommend that you just check the plugs. They are supposed to last 100,000 miles, but since you don't know what the previous owner did, it wouldn't hurt to make sure they look good.

 

[chitown]

I had the same problem according to the dealer on my 3.2. I brought it in because I thought the exhaust was resonating on something and I couldn't find the source. So I thought I'd let them take a look. Prior to that I had a little pinging (probably from the crappy emission-standarded Chicago gas) under heavy load while running the a/c. The dealer took it upon themselves to reprogram the ECM so nowI have no more spark knock, but a little drop in fuel economy. Try searching at the 4x4wire.com for spark knock and you'll get some info on the ECM re-program.

Rob