P1491 is an OBD-2 code, and your 94 is OBD-1. The EGR system has some differences, so you should be aware of that before you go through the whole business you posted up above. Trust the guys who have 93-94-95 cars.

 

looked over the exhaust manifold today...no cracks.

 

My EGR is Good on mom's 92 accord EX.

The EGR Ports have been cleaned.

The EGR Solenoid valve has power at the control box to blk/yel wire when key is on.

I have no vacuum leaks between # 24 from the intake manifold all the way to the #16 line at the EGR Valve.

I Have vacuum at EGR Valve #16 when I run car and connect 12+ to the blk/yel wire and 12- to the Red wire.

The problem I am having is I believe I am suppose to have a constant steady amount of vacuum at the EGR Valve when I'm in Park and I rev the RPM's up above Idle.

For some reason when I check the vacuum at the EGR Valve I get about a split second of vacuum and then the vacuum stop this is while holding the RPM's above Idle.

Please Help.

Thank you,

 

Are you getting a code for the egr?

How much above idle are you holding it. I've only quickly read this, but I think once in closed loop, testing is done ~3K rpm's

 

There is no CEL Codes.

Oh well I have not held it past 3k for any duration of time. but before the RPM's can reach 3k the vacuum has already dropped back off to zero.

I have not reset any thing like the ECU/Computer etc etc etc because I don't know how other than by unplugging the battery.

forgot to mention in last post the vehicle is a 92 accord EX Auto

 

Ok...don't take this the wrong way but "what are you chasing"? I'm sure you didn't wake up and decide to check the vac on the egr....

Next, I'll be honest and let you know up front the manuals I have for the 4th gen are not the best (missing pages and that) but I'm willing to help in anyway I can. Be sure the vac into the solenoid is present.

 

OK yeah I did not Test #24 at the manifold yet to make sure I had vacuum going to the EGR Solenoid Valve but that was on my mind and I forgot to do that. Mom had to take car out to Church so I will not be able to test that until later on today.

The reason I am chasing the Vacuum and EGR issue is because I am trying to pass a smog Test and the NOx is reading 1043 at 15mpr and 883 at 25mpr. which is about double the max allowed.

All the other gases are checking out ok well below max.

Mom claims to be getting sub par MPG lately so I'm thinking this issue once fixed should bump her MPG back up to where it was before I started fixing it for her.

Thank you for the help poorman.

 

OK I just finished testing vacuum at the intake for line #24 and it has so much vacuum that I just about stalled the engine by hooking the vacuum guage up to the intake manifold where line #24 goes.

I also checked to see if line #16 would hold a steady vacuum when the RPM's are held above 3k. Unfortunately the vacuum does not come back on after it drops off to zero even after RPM's are held at a steady 3k+

Does any one have any idea's what would cause this. I was thinking about the Air Temperature Sensor but I have no idea how to test it.

Any and all idea's are appreciated.

 

Any Idea's... Any one?

 

how are you coming along!

are you still searching, or have you got things sorted out?