90 accord rough idle in gear and rough take off
 

I'm am working on a 90' accord lx auto tranny. 140k. The car starts right up idles perfect. When you put it into gear D or R it idles very rough and runs like its on 3 cyl. until you reach 3500-4000 rpm's. Then it runs smooth until it shifts and the rpm's drop below 3500-4000. The car had a cracked ex. manifold and i thought that might have been the prob. but it wasn't. I also put in new plugs and a valve cover gasket because it was leaking oil onto the plugs. Next I was going to look at the EGR. Anybody have any thoughts on this one?

Re: 90 accord rough idle in gear and rough take off (snooking99)
 

IF this condition starts about 1800 rpm and continues to about 2300 rpm, you COULD and I emphasize "could" be dealing with several carbon clogged EGR ports in the Intake Manifold.
If three were clogged off and only one remained, that one remaining cylinder would be asked to ingest inert gasses ment for four (not one) cylinders. This would effectively kill off that one cylinder; and it would act 'dead' within that rpm range.
There are several TSB's from Honda on this subject along with two threads in the Accord FAQ section on the first page of this forum

P

Re: 90 accord rough idle in gear and rough take off (P_Adams)
 

The problem starts as soon as you put it into gear. Like 600-700 rpm's.

Re: 90 accord rough idle in gear and rough take off (snooking99)
 

You may (and I emphasize May) have a broken rear engine mount. This is a vacuum assisted mount which, when it fails collapses to the point that the engine bracket all but rests on the rear crossmember.
The shaking gets so severe that things have actually falled off cars. On my wifes past '88, it got so bad that the front bumper fascia came loose.

The tough part of this diagnosis is that it idles fine while in neutral....

P

Re: 90 accord rough idle in gear and rough take off (P_Adams)
 

It's not a motor mount. The engine doesn't move much.

Try Idle valves
 

I was having trouble with my 1990 Accord EX Auto with having a very strong idle speed. I checked myFast Idle Thermo Valve, the inside plastic ring was loose, fixed that and my car ran better. Then, Chekced my Idle Air Control (IAC) valve and it was pretty much filled up with gunk, cleaned that out and my car ran great after that, even in gear. Mybe givnig these valves a check migth help with your low idling problem. Also, There is an idling adjusting screw on top of air intake manifold, Counterclockwise lowers RPM, Clockwise increases, migth want to take a look at that too.

Re: 90 accord rough idle in gear and rough take off
 

Have you found the fix yet for your 90 lx ?? Because I am also having that problem