5.2 Liter detonation

[superbee1970440]

I have an ongoing, intermitant detonation or "spark knock" problem on my 99' Ram. When the motor is fully warmed up, under load with light throttle, I hear detonation. It sorta comes & goes.I have had the ECM updated, I installed the "updated" intake gasket set & cleaned the injectors but it still happens. The grade of gas makes no difference.
One of the master techs at a local dealership told me that some of them just are noisy & there is nothing that can be done. I find that kind of hard to swallow. I have owned my truck since brand new & totally love it. It only has 63k on it & I would like to keep it forever.
The problem has been happening for the last 2 years & is driving me nuts!

Any Ideas?

[ehostler]

Turn up the stereo system. Then you won't hear the problem... lol

You've done everything that I can think of, off of the top of my head.

This may sound stupid, but are you sure that it is predetonation (ping)? When I first got my truck, I used to hear what I thought was ping. It only happened under certain load conditions and RPMs. I took it to the dealership and duplicated the sound for them. They toubleshot the problem for a couple of days. Then they did test drives of a couple of other new trucks and heard the exact same sound. That's when they returned my truck to me. They continued to troubleshoot the sound on other new trucks. About a month went by when they called and told me that they had isolated the sound and asked me to bring my truck back in. Turns out it was the bearings in the serpantine idler pulley.

[HankL]

I wrote this several years ago:

http://dodgeram.org/tech/gas/Trouble/ping.htm

if I were to revise it today I would place more emphasis
on removing carbon deposits on a continual basis,
and spend more time pointing out that many Magnum
cylinder heads have cracks from intake valve seat to
exhaust valve seat - particularly on cyl # 7 and 8

[Dennis Jokela]

A 180° thermostat cured the ping in my 92 Dakota 5.2.The truck also seemed to pick up some power with the new thermostat.

Dennis Jokel

[TK]

Put you air temp sensor in the intake before the throttle body...............seems to help me.

[dgc333]

I believe one of the biggest reasons that stock magnum engines have detonation problems is that the pistons are down in the cylinder around 0.050". This pretty much negates the quench area and the detonation resistance quench offers in the closed chamber head design used on a magnum engine.

I built a 360 this past year with zero decked flat top pistons and magnum heads. With the 0.039" head gasket I am using results in an ideal quench distance and 10.6:1 compression. This engine runs fine on 89 octane (haven't tried 87) and that is with 35 degrees of total mechanical advance all in by 2500 rpm. I realize this does nothing to help your situation but does show what the design is capable of.

One thing you may want to try; Take the manifold air temperature sensor out of the intake (mounted at the front passenger side of the intake manifold) and relocate it to the hose just in front of the air hat on the throttle body (don't forget to put a pipe plug in the manifold). This will trick the computer into thinking the air in the manifold is a little cooler than it is and will richen the mixture slightly (I didn't notice and fuel mileage change).

I did this to the engine in my 99 Dakota and it has been one of the most satisfing changes I have made. My truck used to get quite sluggish feeling when it was fully warmed up on hot days. By moving the sensor I no longer get that sluggish feeling.

This and the 180 degree t-stat my just solve your problem.

[superbee1970440]

Hey guys, thanks for all the replies. I really apreciate it.
I think first I'm going to try moving the air temp sensor. Anyone know what thread size plug is needed?
Also, where do you find a 180 degree thermostat. I havn't been able to find one for my motor.
Thanks, Sam.