I was wondering if you guys can help me. A friend of mines has an automatic 90 Accord, and after we took off the intake manifold and EGR to clean, it started to idle roughly, jumping from 1000-2000 rpm in park and neutral. While in drive and reverse, everything is okay. We took it off to clean the EGR valve and manifold cause it was clogged up, but after putting it back together, it started to idle really rough in park and neutral. We checked all the vacuum lines, everything seems to bein place, but we can't figure out what's going on. Give me some input. Thanks in advance!!!

 

Sounds like you either didn't get everything put back as it was or the EGR pintle is not seated and is leaking. Check everthing you removed and all vacuum lines in the vicinity. I'd pull the EGR back off, wipe it clean and see if I could blow through it from the gasket side. Cleaning the EGR is easier if you can pull a vacumm on it with a pump or a syringe and twist a piece of steel wool in the pintle and seat area until all deposits are removed and it shines like new.it

 

Either you've a vacuum leak somewhere, or a vacuum line may have been installed on the wrong port, or has cracked from handling.
A quick test for a vacuum leak (and if you're careful enough, it will point right to it) involves the use of spray Carburetor Cleaner.

Leaving everything intact, start the engine in park / neutral and let it warm up. Using the small tube extension for the nozzle, start spraying the Carb Cleaner. If there is a vacuum leak, the idle will rise and smooth out as you pass where the leak is. Why?
The Carb Cleaner acts as a fuel, and improves the A/F ratio when mixed with the leaking air.

If you suspect two of the hoses may have been mis-installed. Sometimes the Vacuum Hose diagram that Honda affixes to the bottom of the hood survives so you can reference it. It will be your guide.

P

 

I hope this helps everyone.

Same issue here. Took the egr out to replace the oil cap. It was working and rough idle when it's hot, stalling at idle. All the symptoms were the same.

Solution: start the car, if it idles, great, if not put a heavy box on the accelerator pedal till you can get it idling. Find long extension preferably with movable elbow and 12 mm short socket. There are 2 bolts that hold the egr valve down. Back them off untill the idle smoothens. This happens right before the gasket breaks the seal. Back off each nut equally. Than one turn at a time tighten them down equally as well. You will know when to stop when rough idle comes back again.


Ps, this applies to only working egr valves valves taken off for maintenance. If egr valve is faulty, the issue will persist.


Must be said, do it at your own risk and keep away from moving parts while you make the adjustments .

Best of regards