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StripesRef · 01-26-2020, 06:53 PM

I had a car that did that and in that situation it was the tires. It appears that many other believe that could be the culprit. Be careful and good luck.

NeilV · 01-26-2020, 09:03 PM

Great that they found that in this instance it was a EFI issue!

The tires though are still way to old and should have been replaced years ago especially if your considering traveling to the South. We have way too many 6 year old tires fail here in Florida due to visitors running on tires over 6 years old.

Most reputable tire shops will not touch a tire over 5 years old except to send it to the recyclers even if the tire has never been mounted on a rim.

Note that balancing beads can also exhibit odd vibration issues once a tire warms up or after going over an expansion joint requiring you to come to a full stop to redistribute them again. This will often be due to irregularities inside the casing or due to tires being dynamically out of balance such as when balancing weights of different sizes need to be used on either sides of the rim diagonally across from each other.

Please don't put off getting rid of those old tires because the current issue was resolved with a fuel injection repair. They are still unsafe and will only continue to become more unsafe if you continue running them.

88keys · 01-26-2020, 10:59 PM

Quote:

Originally Posted by rschreifels

It may or may not have anything to do with your problem, but if your tires are 9 years old, I would start by replacing them ASAP. At that age, the lower miles on the tires may be more risky than higher miles.

It may fix it, or not, but the tires should be replaced.

+1
We bought used with very low mileage on the RV and had a shudder at a specific speed/RPM. The steering wheel would start to shake.
We thought that it couldn’t be the tires due to the low mileage so we pursued alignment, balancing, etc.
Turned out that the tires were badly dry rotted...so much so that the steel belts had actually shifted causing quite a dangerous situation. The tire shop had never seen such badly rotted tires...and, yet, from the outside, they looked good. Dealer tire paint maybe.

Marshalone · 01-27-2020, 02:45 PM

We bought a 2018 38 ft Jayco Precept a couple of months ago. The front end shook and the steering wheel had a vibration in it going down the road at highway speeds. I was told the tires will develop flat spots if the unit sits for very long. MH only had 17,000 miles on it. We had the front end aligned (it was out) and an after market stabilizer properly mounted (it was not) and then replaced our out-of-round front tires. Alignment was only $180 but the tires......$1450.00 for the pair. Seems to be much smoother now. Worth the money to get these things done.

4WDEd · 01-27-2020, 05:57 PM

Check your ride height. If the air bags raise or lower during the trip, it will put the driveshaft out of alignment, and that will cause the shudder or vibration you are describing.I had that happen on a trip to San Marcos and it took me a while to figure it out. Once I raised the ride height slightly, the problem went away.

asuperheat · 01-27-2020, 06:58 PM

If it was ever towed the drive shaft may not have been reinstalled properly. If not careful when reinstalled they can be misaligned from how they were balanced.

skyexplorer · 01-28-2020, 09:30 AM

this sound like it may be a fuel pressure issue. these engines weren't designed to pull fuel from long distances. If the fuel pump warms up slightly and fuel pressure drops it could be causing starvation under load. codes would show injector misfire but would not show the cause was loss of fuel pressure. a booster pump in the fuel line to get fuel to the pump may be your solution and a lot cheaper then replacing injectors and having problem again.

Jchemie · 01-28-2020, 09:38 AM

So I had a similar problem like grizzly did, shook at times. What pinpointed the problem was one of the times when it shuddered, I was looking out at the drivers side rear view mirror as I accelereated changing lanes. I saw a puff of black smoke from the exhaust. Small, quick, intermittent, but only on acceleration. Final answer was #6 injector was intermittantly cutting out. For some odd reason it didn’t set a code, probally because it was short and infrequent. I thought it was bad fuel or poor electrical connection on the injector plugs. Clean fuel, new filters, checked connections seemed to work but soon the problem would reappear. Scanner showed no code or problem. Eventually it went south on a long trip, caused a cascade effect down the line on other engine components which cost $$$, had to replace them. Had I gone to a Cummins shop and had them do a cylinder power test, I probally would have found it earlier and avoided some cost and headaches.
But to all the other posts, yes, tires and drive shaft are the first place to look.

Dav L · 01-28-2020, 11:45 AM

The first step towards diagnosing a vibration is to localize it.
Does it change dependent on accel / decel? While braking?
Turning to one side or the other?

The way to determine where is to feel where it is coming from (front / back).

A Wheel vibration is 1/4 the frequency of a driveline vibration.

To isolate motor, change to a higher gear and see if the vibration changes. If so, points towards engine. Not 100% but indicative.

Chargerman · 01-28-2020, 01:15 PM

The OP has posted that it has been diagnosed as an engine/ fuel issue

Grizz_ly · 01-29-2020, 11:45 AM

Thanks for all the feed back thus far. Yes, I will be looking into new tires. The plan atm is: I have ordered a replacement injector, icp sensor, and oil rail o-rings and I have them on hand.
But first I am removing the valve cover to clean and inspected the harness and look for ‘dusting’ on the injector connections and run sea foam-then drive to our next destination (4-5 hr drive). If it’s still shuddering I will at our next stop drop in the new injector and sensor. IF it still happens after that I will drop it off at a service center...

damguy22 · 02-09-2020, 07:53 AM

you are on the right track. this is a power issue. it will be hard to isolate. Transmission could be a part. since its under load beat bet would be to see if a tech could drive it with a computer hooked.

Grizz_ly · 10-18-2020, 10:22 AM

Just as a final followup: we stopped at 3 different repair shops to have the issue diagnosed. 1 charged us $ and the other 2 didn’t. The only thing that ever showed was an injector 4 issue but it was never active even when driving (so they weren’t sure). The cheapest thing for me to do was replace the injector myself and see if it fixed the problem. If not I would head down the rabbit hole.

Thankfully though I replaced injector 4 and all is well. No more shutter. To anyone wanting to do this themselves it was not difficult at all. The high pressure rail was heavy but still it was rather easy. My injector harness had no frays. It took a couple hours at most and after exchanging the injector it only cost a few hundred dollars.

Thanks for all the suggestions.
Zac