Honda Prelude Forum banner
1 - 20 of 23 Posts

·
Registered
Joined
·
7,661 Posts
Discussion Starter · #1 · (Edited)
A while back I related how my Prelude failed emissions test because of too high nitrogens of oxide. I found my EGR was not functioning.The valve itself was opening but nothing was getting into the intake ports. After Trying to find a place that could clean them, I decided to take the matter into my own hands.

I removed the manifold. The EGR chamber is above the intake runners and I noticed that there were these welded (?) over projections over each runner. So I figured that this is where they drilled down thru the EGR chamber and into the runners. I drilled thru the top with a 27/64" drill ( that's the size you use for a 1/2" course thread tap)



I was right, the intake runner ports were directly under where I drilled. I cleaned the runner ports with a small drill bit (hand held) and cleaned the entire chamber out with oven cleaner and a 44 caliber brass bore brush.
The oven cleaner kicked the crap out of the carbon deposits but turned the aluminum dark gray..:shock::shock:

Then I plugged the holes with 1/2" x 1/2" allan key plugs with hi-heat silicone in the threads. The places with the roman numerals are the actual runner port locations the others were opened up in order to clean the system out.



It worked...car passed emissions with flying colors.
 

·
Registered
Joined
·
7,661 Posts
Discussion Starter · #5 · (Edited)
Not really. The only difference was that the idle went up to 1500 RPMs. I had to reset the little throttle stop screw down a bit. Must have been because I cleaned out everything while I was at it.

I had the intake plenum and throttle body gaskets left over from Honda's gasket set from 8 years ago ? So I just took everything apart.
 

·
no mo mod
Joined
·
13,011 Posts
ah, thats what a lot of techs do to hondas.
seems like a little bit too much work for my liking...
*shrug*
least you know its all cleaned up now :)
 

·
* * * * * *
Joined
·
12,918 Posts
tsiah said:
ah, thats what a lot of techs do to hondas.
seems like a little bit too much work for my liking...
*shrug*
least you know its all cleaned up now :)
pff u can't even get an engine to work properly



:D loser
jk :turn:

Good job dano.. you're retired right? Man.. that's old. :p
 

·
Registered
Joined
·
3,211 Posts
LudaPower said:
pff u can't even get an engine to work properly



:D loser
jk :turn:

Good job dano.. you're retired right? Man.. that's old. :p
ouch thats a little harsh... its better than all the crap i have seen you rig together on your prelude, good job Dano..this is a pretty common problem on hondas...pretty much all the accords 90 and up are much easier to do it on then the preludes of our gen.
 

·
no mo mod
Joined
·
13,011 Posts
b20luda said:
ouch thats a little harsh... its better than all the crap i have seen you rig together on your prelude, good job Dano..this is a pretty common problem on hondas...pretty much all the accords 90 and up are much easier to do it on then the preludes of our gen.
is this the way you guys fix em at the dealership?
 

·
* * * * * *
Joined
·
12,918 Posts
b20luda said:
ouch thats a little harsh... its better than all the crap i have seen you rig together on your prelude, good job Dano..this is a pretty common problem on hondas...pretty much all the accords 90 and up are much easier to do it on then the preludes of our gen.
:Rock:
Kiss my ass.. I was just joking dude.
 

·
Registered
Joined
·
3,211 Posts
tsiah said:
is this the way you guys fix em at the dealership?
I have never personally done this on the prelude as we usally dont get them in for this kinda stuff people dont wanna spend the money i guess, but on the accords and newer preludes etc, this is exactly what we do except most have plugs on the runners, but they are still a chore to remove u have to first drill a hole in the center of it and then use a tap to make threads in the hole u just drilled...then use a slide hammer with a special attachment to pull them out, some model accords have a big plate that unbolts those are the $best$/easiest to do. Its acutally pretty easy to tell if the ports are clogged on automatic cars, when the engine is fully warmed up put the car in drive step on the brake and raise the RPMS (while the brakes are held) raise the rpm to about 1700-1900rpm and u can feel the engine miss pretty bad. And of course on the OBD2 cars its will usally throw a MIL for EGR insufficent flow, its pretty crazy how it knows that there clogged, when the egr opens it will intermintanly drop a bit of vacuum and the map sensor will pick that up, if the valve opens and the vacuum dosent drop it will think the ports are clogged and illuminate the cel. sorry didnt mean to ramble on and on...
 

·
Registered
Joined
·
67 Posts
Good job man. Always nice to see a job well done.
 

·
Registered
Joined
·
856 Posts
Good Post. Now I know what to do when I need to do it. I have my manifold off right now for the engine rebuild on a B21. I noticed those welds and wondered what was in there.
 

·
Registered
Joined
·
2,344 Posts
I have a question about your trouble shooting. I am having the same problem, that my car doesn't pass on NOx. I've done the test where you apply vaccuum to the EGR to check if the car stalls. My car *almost* stalls, but it still runs. I was wondering if that is close enough to think that it's not clogged up. Or should it just die?
 

·
Registered
Joined
·
7,661 Posts
Discussion Starter · #16 ·
BA5 said:
I have a question about your trouble shooting. I am having the same problem, that my car doesn't pass on NOx. I've done the test where you apply vaccuum to the EGR to check if the car stalls. My car *almost* stalls, but it still runs. I was wondering if that is close enough to think that it's not clogged up. Or should it just die?
I guess it depends just how badly clogged the ports are. Mine were completely blocked and tested almost double the PPM allowed. After cleaning the engine would just about stall when vacuum was applied to EGR at idle. I would think your ports are not clogged.

If you just barely failed you may just need to reset your ignition timing
 

·
Registered
Joined
·
2,344 Posts
Yeah, I didn't fail by very much.

Thanks.
 

·
no mo mod
Joined
·
13,011 Posts
BA5 said:
I have a question about your trouble shooting. I am having the same problem, that my car doesn't pass on NOx. I've done the test where you apply vaccuum to the EGR to check if the car stalls. My car *almost* stalls, but it still runs. I was wondering if that is close enough to think that it's not clogged up. Or should it just die?
how much vacuum did you apply?

if you open the EGR all the way, the car should die...doesnt mean it will, but most cars do.
we had a buick at the school that had the electronic EGR...you can open it up with a scan tool...we opened it to 100% and the stupid thing still wouldnt die
 

·
Registered
Joined
·
2,344 Posts
I tried two ways: One I applied about 200 mmHg, which according to the manual is how much vacuum the valve sees. The other way I applied as much vacuum as I could. There was no difference in how it ran when I did this, so I'm assuming that the 200 mmHg opens is all the way, or at least far enough.

I ended up replacing both O2 sensors. Only one was actually bad, but I just did both anyways. I also advanced the hell out of my timing. It passed.

I don't know if the o2 sensors were actually the problem, but I'm just glad it passed.
 

·
Registered
Joined
·
4 Posts
Alright, I've been lurking ever since I bought my prelude. 1989 2.0Si. It's my first car ever, and to be honest when I bought it it was a piece of junk. I've replaced soo many parts in it. The radiator, catalytic converter, alternator, spark plugs, motor mounts, etc... Anyways, my car won't pass smog. The first test I did it passed the emissions the HC unit was one less than the maximum allowed but the timing was off and the idle was too high. The second time, after I got the timing set, it failed the emissions because of too high Nox. I also discovered that it's missing on the first cylinder(the one all the way to the left, i can pull it out and it doesn't change how the engine is running, its running really rough to start with) Could this be clogged egr ports? If not what could it be? I am not typically a car person, this is my first car, so half of the stuff people post on here I don't really understand. Sorry if this isn't posted in the right place, i don't know if it constituted a new thread or not.
 
1 - 20 of 23 Posts
Top