On my 98 SVT it has suddenly developed a very suttle vibration around 2300-2500 rpm. The only reason i noticed it is because thats the rpm i sit at on highway between 55 and 60. I was wondering if there was a throttle linkage spec. I dont know about manuals but in the auto vehicles i own when the linkage stretches a little it tends to cause the same problems. Any input would be helpful i'm pretty confused.
The thing to check is if you have lost some wheel weights (especially after a hard bump). High speed vibration can be attributed to bad wheel balance. Other reasons could be lower control arm bushings and struts.
Well the thing is. I can stop put it in nuetral and rev to that point and the vibration is there. Above or below that rpm its fine.
The check engine light hasn't even come on its running good except for that point. The only mod i've done is an intake which has been there for around 5 months. Is it possible some of my emission and vacumm hoses arnt getting proper flow at that rpm?
I forgot to mention that i also relpaced my spark plugs around a week ago with the Autolite XP plugs. I also need to change my wires soon. Is there a chance i need to pull my plugs and recheck the gap? My first thought was a warped or bent cam or crank shaft, but that would become much worse at higher rpm. this just stops all signs after 2500 and doesnt start until 2300
thats all i've done to the car since i've had it. it took about 4 days for the vibration to show up after plug replacement. just enough to tingle your foot like riding on a rough road.
ok so i've replaced my plug wires and fuel filter and have notice the vibration started to fluxuate on where it wants to appear. When i get on it the engine seems to loose power and come back, the vibration appears randomly through the rpm. Up until recently it only appeared at 2300-2500rpm. Could this be a fuel delivery issue such as a dying pump or bad injector? For the most part it still likes the 2300 to 2500 rpm range to show up though.
A bad fuel pump would show signs of failure when the demand for fuel is the greatest (ie. hard acceleration or ascending a hill) or when there is very little fuel in the tank. Doesn't sound like it to me.
If you have not done any injector maintenance yet, you should try a bottle of injector cleaner in the fuel tank. I like Red Line SI-1. A chemical decarbon might not hurt either.
But the fact that it started happening after changing the plugs may still be significant. Sometimes ignition misfires manifest themselves in strange ways, even with RPM specific or light load misses. Did you look at the plugs again? Did you crack one when installing it (this sort of miss can be from a cracked plug)? Did any of the plugs pick up any strange deposits? Did you try substituting a know good coil?
Lastly, it could be an out of balance problem. The first harmonic for a vibration to show up from something out of balance is 1700 RPM. What accessory on the engine it turning at 1700 RPM when the engine is at 2300 to 2500 RPM? Alternator, power steering pump, air conditioning compressor, water pump? Running the engine briefly with the belt off would confirm all but the water pump.
i've already tried the injector cleaner and pulled the plugs again to check for gap but didnt notice any crack. Is there any specific place i should look for a crack?
The outer porcelin. The portion that is outside the engine, above the threads. It is often at an angle.
would a coil pack from a 96 taurus duratec be a good tester to see if mine is ok. If by chance it is a harmonic balance on my shaft how hard is it to change and how much are the parts?
The 96 coil should be the same.
I'm not talking about a shaft out of balance. I'm suggesting it may be something like the alternator. If you can dteremine which accessory is causing it, replace that accessory (alternator, power steering pump, air conditioning compressor or compressor clutch). Confirm that the problem goes away with the belt removed first.
Thanks i'll repost again when i get a chance to work on it this weekend.
