pressure testers sometime double up as a vacuum bleeder kit and anyone working on Porsches has one in their tool kit. most pressure testers are simply that, they create a seal and you pump pressure to a predetermined level leave it and check later to see if the pressure has bleed down. I use the sykes pickavant one because I needed one daily at the race track or in the workshop but I think there are a few cheap vacuum bleeders around that I am surprised I don't see much of on here, but I don't suspect yours is an issue, unless your seeing a coolant loss at the reservoir, the engine at temp has a coolant pressure of around 15 psi, enough to show itself if leaking out the external part of the engine.

 

Also for future reference here is a picture of the back side of the thermostat housing, and a picture of the ground wire that attaches to it. In one of your engine bay pictures I believe I can see that cable dangling between the battery and your transmission, you mentioned earlier you didn't see it

 

I am going to check for that wire again.
That U shaped hose that you mentioned, I am familiar with that - had a leak some time ago and changed that out.

My thermostat housing location is very tight due to the presence of the transmission (auto CVT) to the passenger side. The bolts are in a recessed space and there is not much clearance for any of the sockets that i have. I gave up trying to change out my thermostat (as maintenance, no problem that I can tell). Perhaps there is trick to it.

 

They are working fine when I checked it last night. I was overthinking it.

 

Swapped out the distributor and cleared the CEL codes. Drove around and drive to work, i notice a flashing CEL around 1.5 to 2.5 K rpm and car shudders and bogs down. I change shift from D to S and that pushes the rpm higher and she settles down. While on D, if I am below 1.5k or above 2.5k rpm, i am fine. This pattern is not seen while idling, I can increase the revs to 2k without shuddering.
The codes are P1399, 0505 and 1491. These may not be all Honda codes as I used one of the wireless Chinese made obd2 readers. I have Actron at home and can double check after work.
Also didn't see the coolant leak after that one time.
She is driveable but the flashing CEL makes me uncomfortable.
Please advise.

 

1399- random misfire
0505- idle control system malfunction
1491- egr lift

all very googleable, this was one of the first hits for p0505 civic https://honda-tech.com/forums/honda-...-here-2127246/
googling p1491 civic hx gets you this Fixing EGR blockage leading to DTCs P0401 and P1491
and wowweewah, a site search here for p1399 civic hx gives you this https://honda-tech.com/forums/honda-...ubled-2989989/

seriously, effort.

 

Do all three codes return after an ECU reset?

 

Haven't done the reset yet.
Is ECU reset same as "Erase CEL codes" using the OBD2 reader?

 

Yes

 

P1399- random misfire detected - probable causes - blocked egr passage, valve clearance out of range

P0505 - idle air control fault. Idle speed is higher or lower than detected by IAC

 

Thanks eghatch for those links. I was going to look them up as well but wanted to post it here as well sooner than later, so that I can get the benefit of combined wealth of experience that this forum provides. I have also noticed that I get a systematic, methodical approach to troubleshoot the problem, which I may not get with google search and I may proceed haphazardly.
Plus, I posted that from my phone before I reached my desk. Hope I did not come across as a lazy, expecting to be spoon fed character.

 

I will tighten the EGR valve cover some more and see. The broken bolt was fixed and uses a different sized bolt now.

 

Also, will tighten down the intake manifold some more (one of the suggestions for P0505). I was gentle with it because I broke the head stud last time. Don't think I am using the torque wrench correctly. But I will just use a 1/2 inch wrench.
I am positive that the EGR passages are clean because I cleaned it thoroughly prior to install.

It is interesting that it happens at that particular rpm.

 

I've had an egr insufficient flow code on all of my hx's, which is why I can get them at a cheap price. None of my prior hx's had misfires associated with a cloggued passage way

However your code could possibly be for egr valve stuck open from contamination, or the egr plate causing a vacuum leak.

 

I may have to get a new EGR chamber gasket as the edged may be worn out with my cleaning plus there may be tiny residual RV sealant used in my earlier effort. Hope my local dealership has one for a good price. Don't see it online (eBay or Amazon).

I had tested the egr valve not too long ago and cleaned it as well. Perhaps it is time to replace that as well.

 

There are numerous potential causes for P1491, including vacuum and electrical problems. For example, you will find three pages of troubleshooting tests for this code in the service manual. Don't throw parts at this problem. You'll likely waste a lot of time and money.

Do the three codes repeat? If so, considering that P0505 is also thrown, the problem may be a leaking vacuum hose.

 

Sounds good. The EGR valve is too expensive for me anyway. The chamber gasket is more reasonable at $14 from Honda dealer here.

 

There is a logical order to troubleshooting. If you're interested in avoiding unnecessary work, reset the ECU to determine which codes repeat. The outcome will guide subsequent troubleshooting efforts.

 

I've literally never had to replace an egr valve.

I would reset the codes and make sure they are the current errors. If they are the current codes I would then start by testing for a vacuum leak.

 

That is what I will do later tonight.

 

I reset the code on my way back from work. When i first started the car it seemed to be misfiring but after some warm up it kind of settled. Then once on the road, the CEL flashed and it read P1399 and P1401. Was able to drive but that shuddering between those RPMs was still there. Haven't worked on tightening the bolts, had to step out with family.
I will be reading up and working during this weekend. Remember, DST ends this weekend.

 

Tightened the bolts and eyeballed the EGR chambers, clean.
Get multiple misfire code soon after reset p1399. Checked that all four plugs have spark, checked that all four injectors were clicking. Pulled injector plugs one by one and noticed that #3 didn't affect the idle. Replaced that injector. Still no joy.
Is adjusting the timing next on the agenda?

 

Does P1491 eventually return again?

 

No. Not yet anyways.

 

How much driving have you done since the last ECU reset? Given that the EGR system code repeated previously, it may be a real code. EGR system malfunctions are notorious for causing engine misfiring on all cylinders.

Pages 11-256 to 11-260 from the service manual in order.