1989 Accord LXI AT 155,000. I need some egr valve guidance. I have a check engine light once the car reaches operating temperature while driving. I also have 12 blinks on the unit under the drivers seat. I have cleaned the egr valve, checked operation and cleaned the manifold where it attaches. There is power at both terminals on the egr solenoid in the black vacuum box. I disconnected the vacuum line from the egr and ran it into the car to check for vacuum while driving. Once the car reached operating temperature and I was going about 35mph the solenoid started creating vacuum. The engine light popped on and the vacuum stopped. I left the car running and checked to make sure there was still power at the egr solenoid which there was. I put a vacuum pump on the egr and it would not hold much of a vacuum. It did hold a little less than 5#. I don't want to replace the wrong part. Please Advise. Thank you.

 

You should be able to actuate the EGR valve pintle w/ the hand vacuum pump. If valve does not move the EGR valve diagphram has ruptured. New EGR valve is necessary.

good luck

 

Thanks for your reply. The EGR valve diaphragm will go up and down.

 

Does your EGR have an electrical connector? If yes, there is a valve lift sensor which provides info on valve lift when commanded by ECM. If valve lift is not detected, code 12 is set.

You've confirmed vacuum is available as req'd to actuate the EGR. Something is telling ECM that EGR valve is not moving.

It is also possible that EGR movement is detected by ECM using MAP sensor (opening EGR reduces vacuum level).

good luck

 

My EGR does have an electrical connector on the top. I'm assuming that this is the valve lift sensor. It does not appear that this is a replaceable part on its own. Is there a way to test the EGR sensor, or should I look at the Map sensor?

FYI - I am also having some idle hunting issues from time to time. I don't know whether these are related. Over the last two years I have replaced the IACV, vacuum advance, both coolant temp sensors on or near thermostat housing, spark plugs, cap, rotor and wires. Bled cooling system.

 

I found an EGR diagnostic chart (could not copy to a new file). Here are wires to check the EGR system. Ignition switch On.

1) Blk/Yellow to EGR "black box", Blk/Yel should have 12v

2) Red, Green, and White to EGR lift sensor.
Red to Green (backprobes w/ connector in place) should have 5V
Wht to Green (backprobe) should have ~1v

The manuals I'm using are available for download from Online Manuals post in DIY forum (86-89 Accord). I was looking at B20A8 engine w/ FI.

Are you sure EGR pintle is moving freely. A sticky valve would also cause your problem. You may need to remove and use powerful solvent to clean movement.

good luck

 

I had the EGR off and cleaned it with a carb/choke cleaner. With it mounted on the car I can push it up freely with my finger or put a hose on it and pull it up by sucking in.

 

You need to download the shop manual and go step/step through diagnostic tree to isolate problem. Based on what you've done, it could be a wiring/connector faulr or ECM.

good luck

 

Will do. I'll let you know what the outcome is. Thank you.