Engine shaking...

[Skandocious]

My truck is in my sig. It has developed a shake at an idle (I think at the rest of the RPMs). I have been trying to find a vibration in my drivetrain for months but I am now thinking it is attributed to something in my engine being out of balance.

So the vibration is pretty apparent at idle, and happens in a constant pattern. At idle it will just be .........bu-bump.........bu-bump..........bu-bump......... You get the idea.

What might be causing this? I changed my spark plugs/wires/cap/rotor a few months ago and I changed the fuel filter the other day. Also replaced the ignition coil with an MSD blaster coil. Any ideas?

 

[blacksnapon]

Does it increase with engine speed, or disappear? Is it related to engine speed or ground speed?

 

[Skandocious]

Does it increase with engine speed, or disappear? Is it related to engine speed or ground speed?

It seems to kind of die of if I idle it up a little bit, but I am also feeling some sort of shake (not sure if it's the same one) at higher speeds. And it is doing this when in park/neutral so its not related to ground speed

 

[blacksnapon]

Vacuum leaks will be more noticeable at idle. Egr valve, isc motor can cause these symptoms. Watch for the no brainer stuff as well (7 and 8 wires next to each other, common misfires, etc.)

 

[Skandocious]

I'm familiar with the EGR valve and believe it to be operating correctly (on a side note, the EVP sensor is new), but what is the ISC motor? FFI shows that ISC means Idle Speed Control... Are you referring to the IAC valve? If that was bad then my engine would be surging, no?

 

[blacksnapon]

Yeah, the iac (intake air control) is the same thing as isc, just depends on where you live. The iac motor can cause a lot of weird symptoms. I've seen weights come off of flywheels (be more apt to get worse with engine speed), flywheels cracking, bell housing bolts coming loose (engine and trans getting out of line). And look at the harmonic balancer (front pulley) and bolts.

 

[Skandocious]

I suppose I could replace the IAC... But I really would like NOT to throw parts at my truck. I do have a new Motorcraft PCV sitting in my garage (since about 4 months ago) since I couldn't get the old one out. I was going to replace it as a maintenance part. Could a bad PCV cause this?

The truck does shake pretty bad at speed though... That has been happening since I had a hairy experience in the mountains, in a snowstorm. Got stuck in a snowbank and tried to rock myself out; drive, reverse, drive, reverse... I let the transmission KICK into gear a few times by giving it gas before it engaged (I know, I was panicked). Ever since then I have had a shake at speed... Feels like a tire way out of balance but I have had my tires balance and rotated tons of times (and checked for out of round).

 

[blacksnapon]

Try removing the iac valve and running carb cleaner through it first. The pcv valve would be another avenue as well! The other vibration, look for a bent driveshaft, u joints.

 

[Skandocious]

U-joints are new, not sure about the driveshaft, I'm going to try balancing it sooner or later. My service manual describes a procedure where you can use chalk and hose clamps to balance a driveshaft. If that makes the vibration go away at speed then I'll take it and have it professionally balanced with weld on weights.

I supposed the vibration at idle could be a different vibration. I've turned the truck off a few time at ~40mph to see if the vibe went away (eliminating the engine as a possibility) and I couldn't really tell if the vibe went away... I'll try it again.

 

[Bob Ayers]

Has it thrown a CEL? If it has, get the codes scanned....

 

[Skandocious]

I've got a code scanner and it is not throwing any codes. I have had many codes in the past but I have fixed them all. No problems there anymore.

 

[Brian_B]

I suppose I could replace the IAC... But I really would like NOT to throw parts at my truck. I do have a new Motorcraft PCV sitting in my garage (since about 4 months ago) since I couldn't get the old one out. I was going to replace it as a maintenance part. Could a bad PCV cause this?

The truck does shake pretty bad at speed though... That has been happening since I had a hairy experience in the mountains, in a snowstorm. Got stuck in a snowbank and tried to rock myself out; drive, reverse, drive, reverse... I let the transmission KICK into gear a few times by giving it gas before it engaged (I know, I was panicked). Ever since then I have had a shake at speed... Feels like a tire way out of balance but I have had my tires balance and rotated tons of times (and checked for out of round).

I know it has been mentioned, but I would suspect a flywheel being cracked, weight thrown off it it, or something of that nature.

You said you were going to get the driveshaft checked.

That rocking to get unstuck (I have done it too) can cause weird damage. It could even be something internal to the transmission. What does the fluid look and smell like?

 

[Skandocious]

I changed the fluid to AMSOIL universal ATF when I bought the truck at around 95k miles, then had the snowstorm incident. ATF still had nice color and smell to it recently but I was getting a strange noise from near the torque converter so I just went ahead and changed it again. This time I used Valvoline dino ATF and the noise seems to have gone away (hard to tell because my truck is straight piped right now and VERY loud).

As for a problem with the flywheel, I've never pulled a tranny or an engine. I do have the equipment for pulling the tranny away from the engine, would this give me access to the flywheel?

 

[Brian_B]

Yes...it should. You might be able to just remove the t-case cover and see the flywheel.

I found one that was cracked around the center by looking in at it.

You might want to let a pro answer that question though. I have not worked on the full size trucks.

 

[Skandocious]

Remove the t-case cover?? The transfer case is bolted to the rear of the transmission... And the flywheel is between the engine and the transmission (bolted to the torque converter if I'm not mistaken). How would seeing the flywheel have anything to do with the transfer case? And whats a transfer case cover? Lol

The guys on the other forum are also suggesting that it could be motor mounts. How can I check those?

 

[Brian_B]

OOPS! Typo. T-converter cover. Sorry.

 

[Skandocious]

Oh okay. So you're talking about that little inspection hole with the grommet inside? Yeah I don't think that the hole is big enough, looking through the hole you can only see the torque converter.

 

[Brian_B]

Umm...No. There is a thin metal plate that bolts on the bottom front of the transmission. You remove it to bolt/un-bolt the torque converter from the flywheel. That cover is what I am talking about removing and looking up in with a light.

Every automatic I have ever seen in my life has one. Most have 4 bolts, but I have not worked on your particular trans.

You need to un-bolt the torque converter before you slide the transmission back.

 

[Skandocious]

Yeah.... The E4OD definitely doesn't have that cover. I also downloaded a TC removal guide and it says:

 

[Brian_B]

look at steps 17 and 18. The cover has to come off before you can get to step 20 (remove converter nuts).