hello , i recently bought a 1994 accord non vtec. my problem is the egr solenoid is on at idle. doesnt matter hot or cold engine, when i start the car the egr on and it idles rough. if i unplug the vacuum line to egr it smooths out. if i unplug the solenoid it smooths out. from what i understand the egr solenoid gets power from ignition and the ecu grounds the solenoid to open the valve. i have replaced the solenoid, all the temp sensors (for gauge, computer, and fans), the ecu, and double checked the vacuum line routings with the sticker under the hood. is there anything you know about this problem ? or did i just get a bad ecu ? which by the way the old ecu did the same thing which is why i changed it. im trying to get it to pass smog. i also checked the wire from ecu to solenoid for short to ground, but nothing.
thanks for any input.

 

Honda ECU's rarely go bad and plus you said you said that you already swapped ECU's and it's still doing the same thing so that pretty much tells you that it's not the ECU. Seeing as how you just bought it my guess would be that the EGR wasn't working and the car wouldn't pass smog so instead of fixing it properly someone just hooked up the EGR to any vacuum source they could and now the EGR is on all the time....double check the vacuum lines

 

yes i double checked the vacuum lines with the diagram under the hood. they are just as the sticker says. why would the ecu turn the egr solenoid on at idle is what im wondering. the power for the solenoid comes from ignition and the ecu grounds the soenoid to open the valve i dont understand why at idle tho ? and i think you are right about the smog thing and thats why they sold it . lol

 

maybe some one grounded the wire before the ecu to close the circuit. Or maybe you just have a short to ground its a pretty old car. Check the wiring all the way back to the ecu and look for damage or breaks in the wires. Could also snip the wire that goes to the ECU and see if its reading a ground at the ECU if its not you can run a new wire instead of tracing the wire through the harness. Good Luck.