engine shakes
 

Hi everyone,

So my 97 honda accord engine is shaking when im stopped at a red light or whenever I turn on the ac or defroster. I changed the engine mounts yesterday and I still have the same problem. Any idea what could be causing my engine to vibrate and make my whole car to shake? The shaking stops as soon as I drive off regardless if the ac/defroster is on or off.

Re: engine shakes
 

the rear mount is RPM/vacuum controlled by the ecm to reduce vibes at low rpm, so troubleshoot the rear motor mount's vacuum control solenoid and check for vacuum leaks or hose blockages. i think below 1000 rpm, the solenoid gets or loses power from the ECM to either apply or remove vaccum from the rear mount. I can't remember which way it works. I think it applies power to the solenoid under 1000 rpm. Haynes manual would tell you. don't have mine (or my factory manual) with me right now. look at number 12 in pic

http://www.hondapartsnow.com/diagram...t-3-461666.png

Re: engine shakes
 

I have a very similar problem.. Just purhcased a new aftermarket replacement mount so i'm going to try that and see if it helps...

If not, i'll check out the solenoid and vacuum system itself

Re: engine shakes
 

I will go ahead and check the vacuum control solenoid on the rear mount. Also would cleaning the iacv or adjusting the TPS help at all?

Re: engine shakes
 

check the solenoid and vacuum before wasting your time and money on a rear mount. It's not easy to change out.

Re: engine shakes
 

cleaning the iacv can't possibly hurt anything, but as far as adjusting the tps, i have never heard of that. tps measures throttle angle, and as far as I know you can't adjust that and wouldn't want to. you may be able to adjust the idle speed, but not the tps.

Re: engine shakes
 

I believe idle speed is what I meant. Is that the screw thats located on the throttle body. If so, and if it doesnt hurt to try out, which direction (counter-clockwise/clockwise) should I be turning it to help with my problem?

Re: engine shakes
 

you would only want to try that as a last resort, since the idle is set at the factory and is not supposed to need adjustment. You can adjust it, but if the idle is off, that usally means there is a problem somewhere or the idle would be fine. also, if you have a 97 ex, the CEL should be on if you have an actual idle issue. If your rear mount solenoid is bad, you will feel the vibration, but the idle can actually be correct. I would first check out the vacuum solenoid and hoses for the rear mount, clean the iacv, clean throttle body, add injector cleaner, make sure your air filter is and fuel filter are clean and you have good plugs and wires, dist. cap and rotor, then maybe try to adjust the idle speed. You must adjust the idle with the engine at operating temp after the fans have come on and gone off twice. there is a screw on the throttle body that adjusts the idle, but you'll just have to look at it to decide which way to turn it based on what it's attached to and what turning it will do. i can't remember.

Re: engine shakes
 

Thanks. I appreciate all the tips you've given me. Ill keep you posted on what worked. I remember at my last tune up which was this past september, everything was replaced except spark plug wires as the mechanic who did it stated they were fine. However they hadnt been replaced in about 3-4 years, so Im going to check them out and see how they look as well. Do you think bad wires would have a big impact on causing my engine to shake at idle?

Re: engine shakes
 

if you have a completely bad wire, then yes, you will feel that. the wires could be part of the problem, but if you have a bad wire you will have a misfire on that cylinder and the check engine light should come on. if you have no codes, then the wires should be okay. if you have a wire that is almost bad, then you may be getting a weak spark but not weak enough to turn on the CEL. you can check the wires with an ohmeter to see if they are within spec-refer to a manual for the resistance spec range of the wires. the longer the wire, the higher the resistance value, so there may be a difference in the ohms for the longest wire and the shortest, but they should still be in the spec range.

Re: engine shakes
 

I will check that as well. Thanks again.

Re: engine shakes
 

The reason i am changing the mount is because my mount was completely shot anyway.. Had to change, so I suspect that could be the primary cause...

I also have to take off my intake manifold soon anyway so that should ease installation..

Re: engine shakes
 

After looking through some receipts from work that has been done on the car yesterday, I remembered that the shop that I had taken my car to, states that the idle speed was adjusted to compensate for the load being placed on the engine from having the ac on.

Long story short, my ac compressor's clutch kept on clicking whenever I came to a stop. It would go back to normal when I took off. As the compressor would keep on clicking, my rpms would go up and down shaking the engine in the process. Would this have anything to do with the problem Im having now as it seems to shake when the ac and defroster go on. Should checking to see if its overcharged or not enough freon be the cause for the engine to shake?

Re: engine shakes
 

a/c freon charge won't affect vibration. When the compressor clutch engages, it will drop engine RPM slightly but RPM should correct itself soon after. If your a/c is cycling on and off quickly, it's usually low on freon. you will feel a vibration when the a/c turns on, but it should smooth out after a second or two. Have you checked your rear mount solenoid yet?

Re: engine shakes
 

Have not checked it out yet, but looking to get it done this weekend. I took a look at the spark plug wires last night and they did look a little beat up, so I'll be replacing them today. Trying everything here as having the engine shake like that just annoys me.

Re: engine shakes
 

I know its been a while since I had posted this problem but just wanted to let you guys know this probelm was caused by a dirty iacv. I had checked the rear mounts vacuum function to see if there was some sort of vacuum leak and everything was fine. So for anyone out there with the same problem I had, hope this helps. Thanks

Re: engine shakes
 

yes it is. i went from A/T vacum controlled rear mount to 5spd EX rear mount in 1 hour with the engine still in the car. its really not as hard as everyone makes it out to be.