My 95 Accord has/had a vibration at idle. In the last 6 months, I have had the timing belts, front and rear motor mounts changed. Also, had a BG injector treatment done at the dealer (free).

Last week, I checked the rear mount and found it would not hold a vacuum. Had it changed again and the vibration is much better, but the engine is still not smooth at idle. Now it is almost more like a buzz.

The front mount is okay.

Here is what I am thinking/questioning;
Balance shaft belt not correctly clocked?
Drivers side or transmission mount? It is really hard to see the rubber on them.


Ideas?

 

How have you been?

Anyway yes your ideas do seem possible. If it was the balance belt, did this happen after replacement or before....meaning, the balance shaft belt usually doesn't "jump" time. Also the rear mount is only "in play" when the car is in gear....so is this felt in park? What is the rpm at idle?

 

Been doing okay, just pretty busy.

Can't recall if the vibration started right after the timing belt job or not. I do remember they had to re-do it as the counter balance shaft seal leaked immediately ( defective seal).

It vibrates in park as well as drive or reverse, although it is slightly worse in drive or reverse. Much improved however, since changing that rear mount.

I think I might check the IACV as well. Is there a diagram handy showing where it is?

 

How many miles are on the current plugs? Have u recently changed the cap and rotor in the distributor or checked them for corrosion ? A bad spark to a cylinder can make a 4 cyl run real rough. I had a zx2 that had to have plugs every 30000 mils or the whole car would shake in drive. The mounts being broke could also cause vibrations but you should b able to feel it in the car when you switch from d to p. Gl hope you find the issue u might also check for bad fuel injector.

 

The entire ignition system is new within 6 months,. I changed the plugs again last week. No change

How do you "check an injector"?

What I need is an old fashioned ignition oscilloscope.

 

I think there is a "how to" in the Common DIY Threads on the IAC. Also, what is the base idle....take a quick look at the front mount, I know it was replaced but if the rear had to be replaced again????

The injector can be tested for resistance and to see if you have power with key on, ground signal when running might be hard to detect.......but IF this is injector related I would say it is either clogged or leaking.....if it wasn't working, you'd be running on three cyl.

 

I'll check the howto. The rear mount is brand new, tested before and after installation.

The engine runs fine above idle (750rpm) I have also checked the ignition timing and run the valves, and checked compression ( all 182-185 )

 

The front mount? Just a guess if the rear gave out, could the front have gone as well?

 

likely the balance shaft belt is not timed.

 

The following procedure should confirm whether rear balance shaft (where oil seal is located) is aligned correctly.

Turn engine CCW by hand to TDC using timing pointer on timing belt cover and timing marks on crankshaft pulley. You can remove the upper timing belt cover (fairly easy but valve cover must be lifted to release) to confirm camshaft is aligned.

Remove the rear balance shaft lock access bolt and attempt to insert a long 1/4" or 6mm bolt. It should go into the maintenance hole & balance shaft 74 mm or 2.9 inches. See shop manual for details. If it will not the balance shaft is misaligned. Fix requires removing upper and lower timing belt covers, crankshaft pulley, and balance shaft belt to realign.

With a good light, you may (not sure) be able to see the forward balance shaft alignment mark down through the lower timing belt cover w/ upper timing belt cover removed. The elongated mark on forward balance shaft should be TDC and aligned w/ pointer on engine.

good luck