Topic: Engine noise

[ml1275]

Hi All

Newbie on here - so be gentle. :oops:

Had my 2.5 for about 6 months and love it. Apart from the fact that I get a pinging/knocking on a 'steady throttle'. It does not do this under load. Jeep knowledge is a bit scarce over here in the UK. Any ideas guys.

2.5TJ - done about 65k Miles.

Cheers
ML

[Jeffy]

What year is the Jeep?  If it's misfiring the PCM should have seen it and recorded the error.  This would be the first place I'd check.  Depending on the year of the Jeep, you might not need a scanner to read it.

[ml1275]

Hi

Not really a misfire more of a pinking / pre-ignition sound.

Done all the usual to sort it out. Changed plugs, dizzy cap, rotor arm, airfilter, fitted accel coil, poweraid and so on.  Front manifold bolt was snapped when I bought it, but the dealer replaced it before collection. Manifold looks like it has been V hot in the past - a bit blued - is this normal.

By the way it is a 97 - I have checked the diags and nothing shows up.

Ta
ML

[Jeffy]

Have you put a timing light on the engine to see if it's ok.  I'm guessing it would be since you haven't mentioned any idling problems.  Have you tried upping the octane of fuel/petrol to see if it goes away?

With only 65K on the odometer, I don't think carbon build up would be that much although it is a possability.  What kind of spark plugs are you running?

Although what RPM does this happen with?  It wouldn't be around 3000RPM would it?  Perhaps a slight incline?

[ml1275]

Idle is perfect. Also it does not do this whilst on warm up. Happens at most revs above 2500. If you back off the trottle to the point where it is between accellerating & decellerating it makes this fairly loud pinging / clattering noise. It is possible to drive around it    but it is a pain in the a**. Plugs look fine. Run it on 95 octane unleaded (98 & 102 is available) but damn expensive - standard 95 is $1.80 a Litre  :shock:  :shock:

Maybe it could be something mechanical - eg camchain tensioner?

Thanks again
ML

[Jeffy]

Well, I'm wondering if it still pings when bumping it up one grade.  This will tell you id it's a compression/heat problem.  Although in the US, most use 87 octane so I would think that you'd be fine.

I know 2.5L's have had a problem with slight detonation problems at or around 2700-3000 if you hold the throttle with a slight load.  Neither accelerating nor decelerating.

Do you have a Factory Service Manual?  If not check the FAQ area.