Early 99 shake up to 1700 rpm

[jdb213]

Hello everyone. Sorry for my first post to be a problem, but I have searched the archives and read all I can to try and solve this issue. First off, the truck is an early 99, F-250, 2WD, 6 speed manual, bone stock as of now. I want to get this problem resolved before any mods. From idle up to about 1700 rpms it sounds like a miss and the gearshift shakes pretty rough. Above that rpm it is relativley smooth. It does this while parked or driving, warm or cold. I have changed the oil and filter, fuel filter, air filter and trans. fluid. I have tried to pull codes several times, but none present. I got the truck from a family member that never worked the truck, it has just been a daily driver. I was told maybe an injector going, but I didn't know if an injector would clear up after a certain rpm. Thanks in advance for any ideas or input.

[Dirk]

How many miles?

An injector(s) or o-rings could cause this. You need to have someone run a buzz test and contrib/balance test on the injectors. Make sure your harmonic balancer isn't coming apart. By any chance have you had a look at the flywheel as a possible cause?

[jdb213]

The truck has just over 120K. I haven't checked the flywheel yet, but was planning on doing that tomorrow if the weather is good. I will also take a look at the harmonic balancer. Thanks.

[Dirk]

I haven't pulled my balancer off (doing that this weekend to install the Fluidampr), but I've seen gas engine balancers start to come apart and cause shaking. I'm leaning more towards the fly wheel or injectors.

There will be a tech along shortly I'm sure.

[jdb213]

Now that I think about you saying injector o-rings it made me think that this morning as I walked behind the truck I kind of smelled a faint oil burning smell from the exhaust. Possible o-rings leaking????

[Dirk]

How much oil does your truck use? What color was the fuel filter when you pulled it?

[jdb213]

Honestly, I've only had the tuck for about a month and a half so I haven't noticed a considerable amount yet. The fuel filter actually still looked pretty clean. There was a very slight amount of a black sediment underneath the actual filter though. Not a significant amount though.

[jdb213]

Finally got around to getting a buzz test and cylinder contribution. My #8 injector failed the cct. Well, that gives me something to do over the weekend. Thanks for the input Dirko.

[Dirk]

No problem. Everyone is here to help! Be sure to run a compression test if you can get the equipment.

[jdb213]

I'll see if I can locate one. Do you know where to start to find a gauge? Mine doesn't near high enough.