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Setting Base Idle Properly

93 accord

93 accord

The 4th gen'er
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Location
Midlands
Car
1993 Accord CB3
This DIY can help with a number of things: Low Idle, Shutting down engine at Idle, Vacuum leak diagnoses, IACV check.

Its a DIY because it only involves a screwdriver!

1) Start engine, let it get fully warm

2) When at normal warmed up temp, remove electrical connector off IACV. Engine will remain running, but at lower RPM or Engine will turn off.

NOTE: If while IACV connector is off, you can not adjust idle down to 600 RPM, then you have a vacuum leak.


3a) If motor remains running, using flat-blade screwdriver adjust idle screw to 600 RPM idle. Idle screw CCW raises RPM, CW lowers RPM. Then, plug IACV connector back on and idle will automatically adjust to about 700-800 RPM.


3b) If engine switches off, using a flat-blade screwdriver turn the idle screw clockwise 180 deg. and repeat step2. Repeat step3b until engine remains running when IACV connector removed. Then, move to step3a, going to step # 4 after. Idle screw CCW raises RPM, CW lowers RPM.

4) Turn off engine. Remove the 2, 7.5A ECU backup/radio (under-hood and in the driver foot well) fusebox fuse for 10 seconds, then reinsert to allow ECU to reset itself.

5) Your base idle is set properly.


Like I said this is a dual purpose DIY as it can determine if the IACV is working properly or not.

It applys to any engine, but this particular DIY is aimed at 4th 5th 6th gen. Let me know if its works for others
 
Sorry to resurrect an old thread, but can anyone help with the location of the IAC valve and the idle screw on a 2.3 Type V?

I'm trying to work through various things that could be causing my car to run poorly and use an excessive amount of gas. I have been told that my EGR valve has to be replaced (£375 plus fitting from Honda - not a chance) and can't be cleaned and that I have an air leak somewhere.

I found the EGR valve easy enough and did clean it - it has made things a little better, but after reading this thread I thought I would try the IAC valve as it mentions proving an air leak.

I ***ume that the throttle body is the 7"/8" oblong silver thing at the back of the bay that the air duct and throttle cable / butterfly housing is attached to? This has a number of pipes and a couple of electrical connectors and I don't know if it is beyond my reach technically to remove it.

Cheers,
Colin
 
I didn't think the idle could be adjusted on the 2.3 but I could be wrong?
 
The point of this thread is to be ressurected and read lol! So no problem

The IACV on your car will be a little unit on the back of the intake manifold just by the throttle body just where the intake pipe joins it.

Run through the DIY and see if that narrow downs your problem.

Remember EGR is different thing all together, although that is also connected to the intake manifold. A bad EGR will trigger a engine light, but IACV will not.
 
Found it!

Honda call it the Rotary Air Control Valve > Throttle Body Honda Parts Diagram

Shabz - no sign of a adjusting screw so you may be right.

Marcus - definitely haven't had any warning light on the dash.

With this information and the various other posts on this site from skhell & others I think I'll give it a go of removing and cleaning it properly tomorrow night.

All I have managed to do tonight is have the air duct off and spray carb cleaner into what I now know to be the throttle body - the big silver thing turns out to be the manifold :blush:

Cheers for your help!
 
Well, just to round it off, spraying carb cleaner into the throttle body definitely did disturb something as the car was not driveable on Tuesday - it stalled or revs dropped to near 0 at every junction.

Last night I managed to get the throttle body and the IAC / Rotary Air Control valve away from the manifold to give it a thorough clean, I couldn't get them out completely due to the coolant hoses but I cleaned them as best I could. I also tried to find the suspected vacuum leak once everything was back together but couldn't.

Same journey today and it didn't miss a beat when stopping at any junction.

It may be me being paranoid but I still think there is something wrong with the car, it just doesn't feel right to me; I am going to leave it now though until it's next service as I can't remove the EGR plate (the only thing that I haven't looked at yet).

Once again, thank you for everyone's help.
 
You also should clean the EGR plate, it could have some holes completely clogged...

Have you reset the engine ECU after cleaning all those things and re-learned the idle speed?
Disconnect the battery for one night( or the clock backup fuse in the passenger fuse box), then start the engine and let it run at 3000rpm until the fans come on at least two times, then let it idle and its done. Do that, it might help.
 
saj said:
^Have you changed the fuel filter?
Click to expand...

Yes, it was changed at it's last service back in May.


skhell said:
You also should clean the EGR plate, it could have some holes completely clogged...

Have you reset the engine ECU after cleaning all those things and re-learned the idle speed?
Click to expand...

I have tried removing the EGR plate (and again after you replied to my thread about it) but I don't want to damage anything as I can't get a good grip on the nuts with a spanner. It will be going in for another service towards the end of October so I'll ask the garage to remove the plate and clean it out properly - I would rather them do it to be honest as I'm not comfortable removing the petrol injectors anyway.

As for the ECU reset, I haven't done that but I see where you are coming from, I'll have a read up on it and have a go at that.

Cheers,
Colin
 
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