94 F150 5.0 vibration around 1500 RPM

[warrenp099]

New guy here looking for some help. I have a 94 F150 with a 5.0. I had the motor replaced a few months ago and got an issue with the change. I get a vibration at 1500 RPM and it goes away as I throttle past 1500. I have the EGR vacuum line blocked right now but it is alot worse with the EGR hooked up. I have looked for vacuum leaks and repaired one but the problem is still there. It does it in Park and Neutral and can be felt while driving at normal cruisng speed of around 55 to 60 because RPM is around 1500 at those speeds. Any ideas? Thanks for any help.

 

[blacksnapon]

New guy here looking for some help. I have a 94 F150 with a 5.0. I had the motor replaced a few months ago and got an issue with the change. I get a vibration at 1500 RPM and it goes away as I throttle past 1500. I have the EGR vacuum line blocked right now but it is alot worse with the EGR hooked up. I have looked for vacuum leaks and repaired one but the problem is still there. It does it in Park and Neutral and can be felt while driving at normal cruisng speed of around 55 to 60 because RPM is around 1500 at those speeds. Any ideas? Thanks for any help.

Last time I ran into this was due to the balance of the flywheel.

 

[warrenp099]

Thanks for the reply. I might would agree with the flywheel except that hooking up the EGR makes it alot worse. I believe it may be something to do with injectors or something along those lines maybe. Once it gets past the 1500 range it seems to clear right up. I may have multiple issues though.

 

[flareside_thunder]

Does it stay running by itself at idle? I'd be inclined to say flywheel or harmonic balancer as well.

 

[warrenp099]

Yes it stays running and runs very well. It only vibrates at around 1300 to 1500 RPM and gets alot worse when hooking up the EGR vacuum line.

 

[blacksnapon]

Yes it stays running and runs very well. It only vibrates at around 1300 to 1500 RPM and gets alot worse when hooking up the EGR vacuum line.

Ya know, do whatever you think is necessary, just ask yourself when is there maximum vacuum? Yep, 1500 rpms and down.

 

[CaFordDude]

blacksnapon
ase master tech--fmc senior master tech

I'm just sayin...

 

[warrenp099]

Ok maybe I should've been a litlle more clear. I should've said engine runs a little rough at 1500 and gets alot worse when the EGR is connected. I believe it's an engine run thing and not a mechanical thing. I unplugged the mass air flow sensor and it seemed to get better. I could actually plug up the EGR without the engine running bad. But I know I can't run it without the mass air flow hooked up. When the EGR is plugged up it runs as if you unplugged an injector.

 

[Lost]

What year motor out of ? Pre 93 Had old firing order . newer 351 layout. I had issues with a maf equipped truck had to redo the injector wiring because of it.

Did a 5.0 replace a 5.0 ? flywheels r different

 

[primetime]

Make sure your spark plug wires are well separated. 1 and 3 I think, and 6 and 5 if I remember right. Sometimes you will get a miss I they are too close.