Easymkay

Hello...new to your forum...thanks in advance for all of your insight. I have a '98 Civic HX, it's a D16Y5 VTEC-E. I have stumble/hesitation on acceleration, and I'm getting only about 15 MPG, although that's harsh summer city driving. I got close to 30 MPG in the past. I had changed my timing belt and H2O pump near the time this started, I made double sure the valve timing was correct (& not off 1 tooth). Its ignition timing, on the other hand, needed to be adjusted from about the middle of the distributors range of rotation, to nearly all the way toward the front of the car. This was many months post timing belt change, but it is timed now. Other things I have done:

-New cap/rotor/plug wires/plugs (gapped, but I skimped and bought autolite plugs)
-New OEM pre-cat ("broadband") and post-cat O2 sensors (when it was throwing code p1167 6-months ago)
-New air and fuel filters
-Oil/oil filter/PCV valve change
-It does have 190k miles and uses 2 quarts oil a month, but its compression is good in all 4 cylinders to this day
-Its oil, however, would turn dark black in just a matter of days after an oil change
-Cleaned it's intake/throttle body with Chemtool


Where I am at now is speculating its catalytic converter (??) When I shine an IR thermometer on the precat exhaust pipe (not flange) I get about 350 deg. F. Postcat the exhaust temp is lower at about 250 deg. I see descriptions of every other temperature configuration scenario, except mine. How should I proceed? If it is the catalytic converter, does anyone have advice on replacement? Could I get by spending less on one than OEM?

Thanks for any help...

Former User

Just buy the NGK plugs listed in the owner's manual. They're cheap. Why skimp?

CEL codes?

Have you cleaned the EGR valve and chamber and replaced the PCV valve?

That's a lot of oil burn. Blue smoke in the exhaust? Or is there an oil leak?

eurochoi

My mother in law has a 98 HX 5 speed, it idled low and had very low power.... I bought an EGR passage gasket and scraped out the passages and cleaned it up. Put it back together and it ran great...

I'd do that next...this is the site I used for the step by step http://www.tegger.com/hondafaq/egr-fix/index.html

nealnanoHX

Did you jump the green plug under the passenger side of the dash near the ECU before you set the timing?? If you did not you will not have a correct timing adjustment. I have a 98 HX and before I did my LS Vtec swap it had 170K on it, good compression, no oil burning and got 40mpg highway and 30 if I beat on it which I did most of the time. Sounds like maybe your oil control rings are shot. With the temps you are getting in and out of the cat it is dead and not firing, but make sure you let the car get good and hot before checking the cat. Generally a clogged EGR will not cause the car to run like crap or get poor fuel economy. The EGR is for emissions reasons, by recirculation some of the exhaust gas you lower the vehicles emission thus making the HX a ULEV. Are there and codes in the ECU or a CEL? Start there and post back.

HeXtacY5

- Have you checked the all the seals & gaskets (rings around the spark plugs)?
- Is there oil in the plug cylinders?
- Have you tried to clean out the EGR chamber? I cleaned mine out & it made quite a difference in MPG & performance.

Regarding the Cat, if you're going to change it you might as well upgrade to better quality, such as a Magnaflow. Thats what I did & it performs & sounds better.

240 killer

my hx is throwing a egr code as well. but im still getting roughly 35 mpgs depending how hard i beat on it. i will be cleaning out the egr so i can get through emissions. stupid md

HeXtacY5

Chances are its the EGR chamber thats clogged and not just the EGR valve. Clean both out and you should eliminate the code. You can see below how the chamber alone can cause the problem. Mine was far more clogged before I cleaned it.

Easymkay

Wow...I feel inundated w/ great info! I will remove the shmautolite plugs and replace w/ NGK like I should've; only CEL/codes this year were the O2/Cat(?) code I mentioned, some VTEC-E code that came up from extreme low motor oil (went immediately away w/ addition of oil), and one that referenced fuel pressure (gas cap was loose); no smoke in the exhaust that I can tell, nor liquid/junk coming out when I hold newspaper over the exhaust pipe awhile, and it's compression doesn't measure bad at all for having 200k/mi. Thanks for the EGR tips. That picture of the EGR inside reminds me of a maze carved in a corn field. When I timed it I also gently increased the idle, because it stumbles at idle to run the A/C at all...in Southern Arizona. BUT NO, I was in a hurry and didn't jump the simple lead under the glove compartment. Betting the computer has reset/undone anything I did (not that I should raise the idle, that was a temporary stopgap). Bad oil control rings sounds very possible, but I'm not getting in there, so I will try all these other suggestions first. I am confused to this day how to read "stored" or historic codes off the ECU. I have a cheap/basic code scanner that isn't very sophisticated. The spark plugs have their metal washers, if thats what is meant by "seals". If it is also the Cat, are you implying (HeXtacY5) that a Magnaflow is better than an OEM Cat? If so, thats reassuring, because it's around $200 instead of like $500-600 OEM. It's a special Cat for the HX and it sells attached to a whole new intake manifold. I read elsewhere NOT to get anything but an OEM Cat.

I have never thrown an EGR code, per se, someone else brought that up. It just seems needing done regardless, in a motor with this many miles on it (200k). I just replaced the PCV above the oil filter, literally 18 hours after changing my oil and filter. I was naive to the fact that it was up there underneath the intake assembly. It was dripping oil and wouldn't "shake the ball inside". It was then I noticed how the oil turned from new, to a deep, sooty black, literally overnight.

I'll try everything mentioned first, and then, with $600 already into both new O2 sensors, I supposed I'll be left "in for a penny; in for a pound", and have to get a new Cat. But which one?

Thanks, all, for taking the time w/ yet another performance/fuel economy threads.

HeXtacY5

No. I mean the large rubber ringed seals around the spark plug chamber. You will see them when you remove the valve cover. But you would know they are bad if you have oil in an of these chambers.

I feel the Magnaflows (stainless steel) are better than OEM (cast iron) in part because each port is independent unlike the stock. Thus, it improves performance. The header & cat is also 1 piece on the Magnaflow, which assists better flow. The Magnaflow cat internals are also far better quality. And yes, the part is different for HXs because of the 2 O2 sensor ports.

FYI, the correct HX cat/header is model # 49282 and will run around $400.

The EGR chamber can be very congested before throwing an EGR code, so consider cleaning it as preventive maintenance.

eurochoi

If you do the EGR cleaning, make sure you take a small drill bit or screwdriver and clean out the small EGR ports on the intake manifold after you remove the chamber cover, they're more than likely clogged almost completely. The one I did had 150k miles on it and it was completely clogged with carbon. It made all the difference, it may not relieve all your symptoms but you'll see a big difference none the less.

HeXtacY5

Yes. An ice pick or anything with a rigid thin tip to unclog those ports. You'll see what we mean when you open up the chamber. You may also use a flat-head screwdriver to scrape out the harder baked-in gunk within the chambers. Mine looked like oreo chunks. And of course, spray everything heavily with carb cleaner.

The entire process should take less than 2 hours from start to finish. Its not difficult, but it takes some time. I definitely noticed an increase in MPG. I cant say how much exactly because I also change several other parts around the same time.

Easymkay

I can tell the main EGR passage is plugged with carbon, so God-only-knows how bad the smaller ones are. To do the EGR and its chamber properly, I have to order the parts, or else risk it by squeezing my own high temp "gasket" out of a tube. Main thing I'm wondering in the mean time is whether or not a magnaflow Cat will match the O2 sensor, and therefore computer, characteristics.

HeXtacY5

Im NOT sure what youre referring to about a "gasket" for the EGR. There are no parts to order for cleaning the EGR system other than carb cleaner. You disassemble the unit & clean it.


As for the Magnaflow cat/header, both O2s bolt on just fine. This is a direct-fit HX-specific cat/header. You will have zero worries there. If anything, the O2s are easier to reach.

eurochoi

It is a good idea to get the gasket/separator plate as well as the other parts listed below so that you don't have fuel leaks since you are removing the fuel injectors/fuel rail. I believe most people recommend Majestic Honda on this site, I don't remember where I bought mine online when I did it.

Just take your time and you'll be done before you know it.

Here's that gasket/separator.


Aluminum washers for fuel filter (2)
EGR Chamber Gasket (1)
EGR valve gasket if you decide to replace or remove and clean valve and ports (1) New valve comes with this gasket.
"O" rings, fuel injectors (4)
Seal ring, fuel injector (4)
Cushion ring, fuel injector (4)
Clean engine oil (to lubricate injector seals)
Honda silicone sealant (tube) (if you buy aftermarket, the stuff MUST be labeled as "sensor safe"!)
Cost of all the parts was around $60 US in 2008.

Easymkay

Ordered a Magnaflow Cat, because I'm convinced I have both the completely clogged EGR (I visualized) and dead CAT issues. I know it's not a V8, but I have NO low end torque, and it now feels like the car just can't breathe at all. Going forward with the EGR/EGR chamber, but damn, ALL those ports and channels...vertical, horizontal, 90 deg. turns. Were you at risk for knocking chunks of carbon down and further into the intake? Even the main passage(s) from the EGR to the chamber maze were completely occluded, and they're large in diameter. FYI, I founds the parts above, suggested to do this right once, to be more like $120 if you get them all. If I took pics they'd be just as bad as this poor SOB, and I have MORE miles than him and use oil: https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/just-cleaned-egr-port-96-civic-hx-pics-included-2151691/

Bad oil rings probably had a hand in both problems. Between worries about dislodging/knocking EGR system carbon chunks downstream, using so much oil, and all the new expensive platinum in the exhaust stream, I would even consider yanking the head. I guess the deciding factor would be if anyone knows whether or not the pistons pull upward and out without removing the block, in a D16Y5.

HeXtacY5

Once you scrape out the gunk & scoop out the ports, just blast each port with Carb cleaner. That'll loosen everything up enough to get whatevers left to flow out of there. After that, if you have access to an air compressor and a gun with a thin nozzle, then try to blow it out for added help. The Carb Cleaner will do the job well enough regardless.

Easymkay

It's number 12 on this blowup: http://www.hondapartssales.com/lisle...s=&view=normal

By squeezing my own "gasket", I meant just carefully sealing the part with red high-temp sealant. Thanks for the other advice Re: air compressor.

eurochoi

I found this picture of the one that I worked with. It was worse than the one referred to in the DIY article too.

Easymkay

Thank you Eurochoi. Your picture tells more than any of the others or any exploded Honda diagram I can find. On the right you have the metal passage chamber, what is on the left? Is that what is considered the gasket to replace? It looks more like a piece you pull, clean, and replace. So what is this third piece that appears to be neither the EGR cover nor its gasket? If you look at Hondas exploded diagram at the link I gave above, the "gasket", per se, would only seal the very perimeter of this assembly. It doesn't have material in the middle like the piece in the left of your picture. What I am trying to say is that the piece on the left of your picture does not exist in the official Honda exploded diagrams. In the labeled picture from your post #14, what do they mean by "EGR gasket 'metal and rubber'".

Easymkay

Here is the diagram

eurochoi

Yes, it's just the "gasket/separator" as you see it separates the top from the bottom and there are small holes in it to allow the gas to pass through the metal. I replaced it because I didn't want to get it back together and have to tear it back down because of a leak...that's your call if you just want to clean it up and reuse it.

The #12 in the diagram is the complete metal and rubber gasket, it comes in a complete metal/rubber assembly just as you see to the left of the chamber in my picture.

Easymkay

Thanks eurochoi, your input is more valuable/explanatory than all 3 Honda dealership parts guys I talked to, combined. This is obviously a really insidious/latent problem that wont necessarily throw a code (even w/ complete blockage), but will necessarily cost people in both MPG and cost a fortune in the wrong emissions repairs.

This is also reason to have a healthy skepticism about trusting the computer. They are supposed to follow scientific rules, but out here in my garage full of reality, that's not always the case. No way could my EGR itself have valve motion; no way any circulation could have been going on at all; no code; talked to Honda: no clue.

Sometimes the dealership don't help because they know they will make $ under the premise that these mysteries are their intellectual property and/or meal ticket. Other times they give blank stares like your the idiot, and you can just tell they're truly unaware. This was the latter.

Easymkay

If "filthiest EGR system" were a contest, I think I should win. Here is a picture of what you will be looking at with components removed. The orange ***** tool has its point at one of the 4 completely occluded ports to the intake. Below that are my before and afters.

I wouldn't suggest attempting this without an air compressor to try to blow out the intake, or a sturdy shop-vac; a certain amount of carbon will inevitably fall into the intake if your ports have complete occlusion like mine. Besides that I used a (sacrificial): toothbrush, "bronze" brush for cleaning welding surfaces, small metal pick, can of carb cleaner.

I should be able to put a tank of gas through before the Cat comes in the mail, so I will post any results in process of elimination style.

eurochoi

Yeah man, it's crazy how nasty those passages get. It should idle a good bit better now though. Good job cleaning it up.

Easymkay

...so with the EEG system all cleaned out I am getting 5 MPG better. I haven't installed the new catalytic converter, I'm waiting to use emissions testing (next 45 days) as somewhat of a diagnostic tool. Performance is still poor with stumbling and now it's throwing code P1165 (primary O2 sensor/manual x-mission so "wideband" sensor) once every several days. I will follow up w/ further processes of elimination so it might help someone...