tastypotato

Hey guys, I've got a fun one for you today.

I have had this check engine light on for quite some time now and no matter what I do I can't seem to permanently shake it.

First off, my Civic has 258,000 miles and has had a pretty tough life. I first got the check engine light on my previous original engine. The first symptom was that under load (70%+) the engine would make really loud pinging noises. That's when the check engine light came on telling me that I had EGR low flow (P0401). It was this and the combination of a couple other things that made me get angry enough at it to just replace the engine. Turns out the replacement engine had the wrong intake for CA smog so I had to reuse the old intake manifold and the problem came right back on a 60,000km Japanese engine.

Okay, so that narrows it down to the intake manifold - so I tried replacing the EGR with a known good used one that I had in another Civic - no dice. I took off the EGR plate, cleaned the heck out of it (Was super crammed full of carbon) and then cleaned all four ports with a .22 bore brush. I kept cleaning until it stopped coming out with crud on it.. Still no dice.

I gave up and took it to a mechanic. He suggested that the Catalytic converter was plugged up causing backpressure in the system and causing the EGR to misread. Replaced the cat with an entirely brand new one (The guys at the exhaust shop told me the one I replaced was not clogged and showed me with a flashlight.. Doh) That didn't help either.

The only thing I have left to replace is the entire intake manifold and I really don't think I can source a manual 97 Civic HX CA legal intake for very cheap.

Also, I think I need to stop taking my car to this mechanic, he is most likely stumped and shooting in the dark which is going to kill my wallet.

As a note: the pinging problem goes away if I put 91 octane gas into the car and then put additives in.

Yesterday I shoved a big metal pipe cleaner into the exhaust port and ran it around a bit and wasn't able to really pick up any extra crud. Cleared the code, and then got it back again last night coasting down a hill with my foot off the gas in gear.

Thanks in advance, I really need your guys' help.

Former User

Manual or CVT?

tastypotato

If it was the cvt I wouldn't have made it to 250k miles. It's the five speed.

Former User

You assume the EGR valve is fine, but have you cleaned it with carb cleaner?

tastypotato

I've cleaned both of the EGR valves that I have by almost literally soaking them in carb cleaner and scraping out the gunk. In my previous Civic (That had the EGR valve that I have on it now) that I wrecked I did not have the pinging nor the CEL. Unfortunately the intake manifold was ruined in the crash. :/

I followed this guide: http://www.tegger.com/hondafaq/egr-fix/

tastypotato

Something about going down a hill with my foot off the gas and using compression braking can guarantee that the CEL is going to come back. Does that help anyone?

Also, using higher octane fuel prevents the pinging noise from happening, not quite sure if it stops the CEL from coming back, I might go put 91 with booster in it next tank and see if I can keep the code from coming back. If it does, does that provide any extra help?

tony_2018

What is the cell code? You probably need to clean deaper in the egr passageways.

tastypotato

Check the first post. It's P0401.

tony_2018

Post edited, I skimmed through it.

tastypotato

I don't know how much deeper I can clean:
https://i.imgur.com/SNoxd2W.jpg
https://i.imgur.com/OkNYsCj.jpg

And the intake side will suck a towel in there's so much of a vacuum leak.

tony_2018

What about the other passage ways. If you look behind the injectors because there's a plate that leads to the egr that you need to clean as well.

tastypotato

I don't want to be a jerk because I really appreciate the help but can you read my first post please?

tony_2018

You know what code is for right, insufficient flow on egr

Either A) passages are clogged
B) egr not opening

tastypotato

I know what the P0401 code is, I've been working on this problem for months and spent over 500 dollars trying to get it fixed.

Okay, I'll order another EGR valve then because I've cleaned everything in the system and the valve itself must be faulty. My mechanic must have lied to me when he told me that he was able to open it with 12V hooked up to it.

tony_2018

Take a pic of your egr valve plug.

tastypotato

On the valve itself? Will do! I don't have my tools on me at work but I'll post a picture first thing when I get home and it's light outside.

tony_2018

In the images it shows the egr valve opening. One leads to the cylinders, one leads to the cylinders. The passage leading to the cylinder has a tiny hole, did you clean in there?

tastypotato

I have, I've put about a quarter of a can of carburetor cleaner in there too just to be sure.

I ran the car with the EGR off but plugged in. I tested to make sure that there is vacuum by holding a microfiber towel next to the hole - it sucked it into the towel.

Also, the car ran like this with the EGR off - I've been reading around and supposedly the car should stall with it off?

tastypotato

Pictures of the underside of the EGR.

https://i.imgur.com/DhA5rYx.jpg
https://i.imgur.com/SUvzQz4.jpg

tastypotato

Bump. Anyone?

tony_2018

Is the EGR hooked up to a good vacuum source?

edit: Is the EGR control solenoid operating?

tastypotato

This specific egr is electrically driven, no vacuum.

Do you know of a place where I can jump 12v safely to move the solenoid in and out? My mechanic that I took it to said that the solenoid on it was functioning fine but I don't know how much I can trust from him.

tony_2018

99 ex models do not have an egr. Unless the wrong ecu was used.

tony_2018

That's the main reason why I ask you to take a picture of the plug. How am I to determine if it's vacuum driven or electric?

tastypotato

I thought you were asking for a picture of the plug as in the plunger underneath the bottom of the EGR to see if you could spot a clog. If so see post number 19.

I pulled off the EGR again today and ran some irrigation tubing down the line that leads into the combustion chamber then hooked that up to a can of carb cleaner and sprayed more down the hole and then used a chopped up coat hanger to try and scrape out any extra stuff. I managed to get more carbon, but the engine still pings under load which means it's probably just a matter of time until the 0401 is back.