Engine shakes bad :(

[92BronK]

The engine(351) in my 92 shakes bad like it wants to stall but never does,but as soon as i step on the gas its smooth.What could be wrong? Could it be that i need a tune up or any type of sensors?

 

[Big Country]

you might want to tune it up. or check the idle sensor. it sounds like it's idling too low.

 

[snowman74]

Just a shot in the dark here...

If it acts like it wants to stall, but doesn't...and it smooths out once driving...maybe you want to check the motor mounts and make sure the engine isn't torquing one way or the other too much. It wouldn't hurt to check them anyway. Just a thought.

Snowman74

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[Broncoholics]

I had a low idle miss in my 89 for years. I added MSD ignition, replaced the injectors, tune ups, the works. I then found out when doing an air leak down test that the valves in the heads were leaking. The compression test didn't catch this as it isn't enough leak.

I pulled the heads and found that the valves were revessed up in the head by 1/8". When I brought them to the machine shop the guy said its due to not having case hardened valve seats. The old style heads need leaded gas additive as its no longer available at the pumps. With rigs these days who knows what year motor or heads you got in there. When I got my truck it had a new motor but old heads. Once I reinstalled it ran like a new truck.