Hello,

I have searched and searched for someone who may have had this problem, but cannot find any posts with exactly what I am experiencing. The car is a 1994 Honda Accord DX with almost 190,000 miles on it. I have been driving it for the past 8 years now (I got it with 130,000 miles on it). And I have had this issue for almost as long as I have had the car.

First of all, this happens when going on higher speed interstates (75mph speed limit) between 75-80mph and between 2400-2600 rpms. It feels almost as if I am driving over a gravel road (one of the bad ones with all those ridges in them) and it seems like the whole car shakes/rumbles. When I let off the gas and lower the rpms below the previously stated ones it stops. I am not sure if it really has any correlation with going up/down hills as it seems to be more rpm/speed related. Also another note: this doesn't always happen between the rpms/speeds listed either.

My father and I changed the timing belt at 180,000miles but the issue happened before this. We also have changed both cv joints, tie rods, and control arms but I still have this issue.

I have read a lot of different posts on here with similar but not exact issues. Some say clean egr ports, some say wheel bearings, etc.

My Dad (retired mechanic) just says just drive slower, but that is no fun is it!

Thanks in Advance for any insight!

 

Is the suspension lowered at all? And when was the last time the wheels were balanced and an alignment done? Crazy excessive toe could cause the tires could be fighting to go straight, improper wheel balance can cause a vibration noticeable 45+, and the cv shaft brand would be helpful also since brands like duralast don't seem to last long. Feathering on the tires caused by weak shocks can cause a shimmy at higher speeds also

 

shitty tires?

 

All four tires have been recently replaced and balanced (within the past year). It has done this before and after tires have been changed. I also rotated the tires. My car is stock (with the exception of an amp/sub). Not sure I remember the brand, I get most of my parts on rockauto. I have not aligned the car since I got it, the wear before I replaced my tires was even so I figured it was good enough. This has done it before and after replacing all the parts in my previous post.

 

The alignment should be done anytime something like a tie rod end is replaced or turned, is a good idea even without a repair having been performed. You say 2400-2600rpm - 75/80mph, have you checked to see for certain it's vehicle speed related and not engine speed? Because there are a lot of possibilities without narrowing it down

 

I watched it on my recent long distance trip I took. I used to think it was speed related, but on this trip I paid close attention and I believe it is rpm related (which made me think maybe it was the mounts?).

 

Drive on the high way and if it shakes on acceleration but it smooths out when off throttle
Or put it in neutral while driving and if it goes away its most likely bad axels

 

Have you noticed any excessive shaking @ idle? It mount issue is possible...

 

It will keep shaking (if it starts shaking between 2400-2600rpms) if I accelerate until I get approximately above 2600 rpms. It doesn't shake because I accelerate (if that answers your question).

Isn't putting your car in neutral at high speeds then back in gear at said high speeds very bad for your auto trans??

It goes away if I let off the gas because my rpms drop right away.

No more shaking at idle than I remember when I first got it. But it does shake more than my fiance's 2000 sunfire (which just replaced the upper mounts on). I mean sometimes it is smooth, and sometimes the steering wheel will bounce slightly at idle. I guess it kind of depends? Sorry if that doesn't make sense.

Thanks for all the replys though!

 

As long as you rev match the rpms to the speed you will be fine.

If the shaking/bucking only occurs during part throttle cruise, and you have never cleaned the EGR ports, I would do that first.

On 94-97s it is very simple to clean.
Check the Accord FAQ at the top of the page for the How To.

Verify the EGR valve operates smoothly. With the engine COLD, gently pull up on the backside of the diapragm with your fingers, if the valve feels a bit crunchy it may have carbon built up on the shaft. Manually exercising the vale to fully open a few times may help remove the crud, you may need to add a bit of lubricant to loosen up the shaft.
EGR valve gasket is ~$2, and will be the only cost to clean the EGR system.

Only changes I would make to the FAQ procedure is to not use a cleaner initially, it just makes a mess/slurry of carbon goo, just scrape out the carbon while vacuuming at the same time. It will be the consistency of burnt brownie residue, so some will be easy to scrape off other bits will be hard as granite.

A set of cheap picks will aid in cleaning out the crevices. But your main two scraping tools will be a #1 and #2 flat blade screwdriver. These fit perfectly in the ports and channels of the EGR manifold. Do not dig into the metal, just gently scrape away to clean the channels.
In the actual ports of the intake manifold they are stepped, so first use the #2 flat head to clean out the port by simply turning/screwing into the port and using the vacuum to constantly suck the junk out. When you come to a ridge about 1/4" in do not force the screwdriver. Switch to your #1 flathead and continue to screw it in and use the vacuum to pull out the loose carbon until you break free.

Set aside at least an hour for cleaning out all the ports, take your time. Cleaning the EGR manifold itself was what I spent most of my time on, the passages can be well clogged.

And when refitting the injectors/fuel rail DO NOT USE SILICONE GREASE. Use typical wheel bearing grease. Silicone will kill a catalyst.

 

Okay, I cleaned my egr ports and valve. It was completely blocked up and filled with carbon deposits. I noticed when I started it for the first time after cleaning, the engine sounded quieter/smoother. I will have to see when I get on the highway if this helped. I also replaced all my heater hoses and radiator hoses, along with the thermostat since I believe the hoses were all stock (with the exception of the upper radiator hose that I recently had a leak in). All the hoses where in great condition still after 20 years.

 

I hate to bring up an older thread, but I drove on a 6 hour round trip recently and noticed this issue still occurs. It doesn't seem to shake as bad or as often, but it still does it. The front wheels seem fine, I pulled on them and they do not give. I also changed my rotors recently and didn't see anything out of the norm for any of the suspension parts.

It might have gotten better because I noticed my rpms were not as high as before the egr port cleaning. This may just be a fluke, or maybe because I was running the A/C intermittently so the engine had more of a load on it.

Any ideas on what else I should check?

Thanks!

 

the rear trans/engine mount is computer controlled to soften when idling in gear and to stiffen when accelerating or decelerating. check that out and see what you come up with... the service manual should explain the procedure for testing the mount.

-chris