Rattle under load.

[BigOne]

Just recently purchased my '94. Took it on it's first real run today, 350 kilometers. Combination of highway, backroads, gravel with a bit of 4x4 along the way.

The vehicle runs really well, with one exception. When pulling up a hill, under load ( over 1/2 throttle ) I get valve train rattle. This would indicate timing is off.

As these engines are computer controlled, what in your experiences would be causing this? When it does it really hard, the check engine light comes on then goes off again when I back off and the rattle lessens.

Should I be suspecting something like a MAF sensor? Maybe need to run some injector cleaner in my fuel for a bit?

I'm new to this vehicle (less than a week) so any help would be appreciated.

Thanks.

 

[Ric94]

"Pinging" can usually be cleared up by cleaning MAFS.do a search to see how its done.

 

[BigOne]

Thanks, yes, I'm going to give that a try.

I did a search before making this post, but it seemed more like they had been referring to a constant pinging or knocking as opposed to the situation where it only happens under heavier acceleration loading.

Thanks again, MAFS is on it's way to a new life.

 

[asdfioo]

Mine did the same thing. Every time I took it above around 2500 rpms, it would sound like somthing was loose. I have never heard an engine ping before so I didn't know what it was. After I cleaned the MAF it went away. Good luck with yours.

 

[BigOne]

Thanks guys, next set of days off out she comes

 

[UTexplorer51]

spark knock

The pinging you here is spark knock and can be cured several different ways. The first is to run some 93 octane gas through and see if it quits. If it does, then just use 93 in it everytime it starts up again.

The second thing is to look and see if your plugs, wires, and coil is worn. You can check the resistance on the coil by taking it to AutoZone and have them look the resistance up. If anything is bad, then replace it.

The last thing to try is to unplug the Mass Air Flow sensor and drive around. It won't hurt the engine, only make it a little hateful. It will rumble and burn off a lot of carbon deposit within the plenum because it will be running rich, but if the pinging stops, then you know that is your problem. Cleaning it won't always work unfortunatly, so eventually it will need to be replaced.

The reason it is knocking b/c of the MAF sensor is because it is sending the wrong information to the computer. The computer controls the air/fuel ratios. If it has bad info, then you get the knock. The engine either runs too lean or too rich, or you may have early detonation of the plug.

This is my first post back on the message board. Good to be back.

Brian