I have a 93 Accord with strange idle/performance issues. The first thing I did was remove the AIC valve and clean it and replace the gasket. This seemed to improve and bring up the idle slightly. I also watched this video thinking there was actually an idle screw to adjust.


At 1:15 he points to the screw. I adjusted this out and it did indeed bring up the idle but then it also seemed to cause more problems then it fixed. First thing is it sounded like there was a vacuum leak when it was running. Then when the car was cold it was idle high/low/high/low. So I screwed it back in all the way and then found that upon trying to accelerate the car would cut out like it was running on 3 cylinders. So I then backed it out slightly, maybe 1-2 turns and it seems to be back to square one and running OK but not perfect.

What is this screw and how is it properly adjusted? it seems to be quite loose to turn.

 

Screw is adjusted w/ Idle Air Control Valve (IACV) disconnected. Adjust to 550 +/- 50 rpm, reconnect IACV, and reset ECM to eliminate code that will arise due to IACV disconnect.

Also you should clean throttle plate (both sides) and throttle bore around plate w/ throttle body cleaner.

Vacuum leaks can be detected by spraying liberal stream of water around supspicious connections listened for engine rpm change.

good luck

 

There's an O-ring around that screw, maybe it's hardened or broken? That would be a vacuum leak sounds like what you might have.

Remove the screw completely to see the O-ring. Parts drawings show that O-ring isn't a separate part, but comes with a new needle/screw.

 

I checked that and it does seem like it could use replacing. Someone had bandaided it by stuffing some sort of sealer in the screw. The oring is there but more like hard plastic then rubber.

 

So unplugged the IACV and adjusted to 550ish. Disconnected battery, reconnected IACV and then reconnected battery and started. Car seemed to idle very low, around 650. Dash was shaking. I took it for a drive and after drive it seemed to be hovering around 850-900 and no shaking. I suspect maybe there's a bad motor mount somewhere because the shaking seems excessive and a little lurchy driving.

Two questions, what is the correct idle when IACV is plugged in and all the accessories are off? Is there a common motor mount failure that causes the shaking?

 

Idle speed should be 700 +/- 50 rpm w/ low load. W/ high load (AC or headlights+rear window heater) rpm is 770 +/- 50 rpm. Some misinterpret the RPM gauge markings. First mark is 500 rpm.

good luck

 

Oh really? The first mark is 500??? I wasn't sure and was going to plug my scanner in and realized no OBDII on a 93. So I was just going off the tach. I have it set too high then if that's the case.

I believe my front torque strut is bad adding to the shaking so that's going to get replaced.

 

Base zero mark, first large mark is 500, 2nd thin mark is 750 rpms. Frequently confused.

good luck

 

This is the 500 mark? And each hash mark above it would be +100?

 

Yes, my 94EX only has one intermediate 750 mark.

good luck