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Fun with a 4 cylinder engine.

Fun with a 4 cylinder engine.

Fun with a 4 cylinder engine.

(OP)
My daughter took off to Hawaii to study for the summer and left me her 95 Honda Accord with the request 'someone drive it once in a while'. About once every week or so someone has actually driven it. About three weeks ago my son came back and told me it's now missing. I took it out and sure enough, it misses very uniformly and only between about 1,400RPM and 2,000RPM. It's so uniform most drivers would likely not realize it.

So as a straight up shotgun approach I changed out the plugs. No change.
I replaced the wires. No change.

We've trolled the web for hours and found dozens of references to people having the same issue - but not one resolution.

Someone mentioned that removing the EGR hose stops the miss. INDEED! It absolutely does. Pull the vacuum hose and plug it and the car runs perfectly. The same thread stated that replacing the EGR valve made zero difference. I pulled the EGR expecting to see soot clogged ports I could possibly clean out. Nope. The ports looked amazingly clean with just a weee bit of 2 dimensional soot coating the port walls.

It was suggested that maybe the O2 sensor is toast. Replaced that today. No change.

Do any of you motor-heads have any ideas?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Fun with a 4 cylinder engine.

I don't have a Honda, however my older truck started doing the same thing a few weeks ago. May not have anything to do with your problem. However, replacing the O2 sensor and fuel filter had little change.
I haven't tried the plugs and wires.

I changed the brand of gas I use and it seems to be doing a little better. In my case I am hoping it was just bad gas.
It's hard to run through a tank of gas when a vehicle gets above 25 MPG, as it requires more than a week per tank.

Hope this helps. Car problems are a pain. I am interested in hearing your conclusion.

RE: Fun with a 4 cylinder engine.

Along with the wires, I'd replace the distributor cap and rotor too.

RE: Fun with a 4 cylinder engine.

since the removing vacuum from EGR Valve eliminates the miss, I would investigate the circuit/logic that controls the EGR valve.

if it is misfire from excessive EGR, wouldn't that mean there was reduce A/F being admitted and thus it might be a design logic for fuel econaomy?

RE: Fun with a 4 cylinder engine.

The car is displaying the classic symptoms of a clogged EGR valve. You really need to take the exhaust manifold off and clean out the ports there... I can almost guarantee some/all of them are plugged.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Fun with a 4 cylinder engine.

How about running the car with each plug wire disconnected in turn. See if this is one cylinder or multiple random misfires.
Of course, the computer may try to compensate and make this test meaningless.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Fun with a 4 cylinder engine.

If you find yourself having to clean the EGR valve, aerosol oven cleaner is fairly effective once you carefully remove the larger lumps. An ultrasonic bath with suitable cleaning solution would likely be better. EGR cleaning on diesel engines is the stuff of nightmares. mad

RE: Fun with a 4 cylinder engine.

Can you do a magic key sequence and it will blink the error code at you through the check engine light? I think that's how OBDI stuff works, right?

RE: Fun with a 4 cylinder engine.

(OP)
Thanks everyone for the input! I've always considered plugged EGR runners but wanted someone to tell me it was 'part X' rather than that gruesome task. LOL

I will first check the electrical/vacuum circuits as a last 'easy' repair then I'll have to turn to the EGR runners. My problem is that if the EGR is disabled and the miss stops why would partially/fully clogged runners cause missing??

The cap and rotor while looking 'used' don't looked used-up and I sort of think the problem would extend to higher RPMs if it was a rotor/cap issue.

Thanks for the cleaning solutions.

Thanks for those two links too. I was thinking this morning that maybe there's a Honda technical service bulletin that might address this since obviously I'm not the first lemming to have experienced this specific problem.

I'll get back with a solution when it happens.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Fun with a 4 cylinder engine.

something I think I learned while reading those links about EGR runners was that the "newer" engines are design to operate with a certain % egr and without it, the engine would be damaged. this is contrary to my 1970's automotive knowledge of emission controls where blanking the EGR was good for the engine (but bad if you got caught).

Sad comentary of my life is that for the most part for the last few decades a car was put gas in, turn the key and go

RE: Fun with a 4 cylinder engine.

By all means, get the diagnostic tool and ask the engine computer what it thinks is going on.

Mike Halloran
Pembroke Pines, FL, USA

RE: Fun with a 4 cylinder engine.

Quote:

....About three weeks ago my son came back and told me it's now missing...

When I read that part of the OP, I couldn't help thinking of the now infamous pilot "snag" report:
Pilot: Right-hand engine is missing.
Mechanic: Right-hand engine found on right-hand wing, after a brief search.

STF

RE: Fun with a 4 cylinder engine.

SparWeb, there is a hilarious gripe sheet from Qantas Airlines mechanics somewhere on the web. Don't have time to look right now . . . It is well worth reading, just don't have a cup of hot coffee in hand while doing so!

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Fun with a 4 cylinder engine.

Found it. I think someone may have posted similar a few years ago on Eng-Tips.

http://www.rb-29.net/html/03relatedstories/03.10.f...

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Fun with a 4 cylinder engine.

(OP)
Fixed. Whew.

Went on to replace the EGR valve after much thought and dragging a scope out and watching the EGR and the PWM running into the EGR solenoid. Installed the new EGR and it worked... worst yet.



Here's an interesting shot of the PWM (top) controlling the EGR solenoid which supplies vacuum to open the EGR valve.


The bottom trace is the analog pot built into the EGR valve to feedback the amount of opening to the engine control computer, ECM. This actually looked ok but I had the feeling the EGR valve was way out of calibration and opening way too much with way too little vacuum. I suspect I was correct because the new EGR valve made the engine run considerably worst. :/

So I finally decided to eliminate the clogged EGR runners possibility. I'd been dreading it because it looked like at least 4 or 5 hours of work involving fuel messes etc. Watched a YouTube video of a mechanic doing exactly the same car. !! Easy. You pull just a few vacuum lines (4), unbolt a solenoid, pull three 10mm nuts, and pull the entire 'fuel log' which includes all the injectors out at once and bend it up vertically with all fuel lines intact. This means you never even open the fuel system.

Once the log is out you're looking straight down on the EGR runner manifold which comes off with 5 10mm bolts. Got my returned daughter scraping out the galleys and then dug out the orifices.
Note the four holes next to the bolt holes? The top three were completely blocked. This left only the bottom hole open. When the EGR valve opened it sent ALL the recirculated exhaust into one single cylinder. Hence, the steady miss.



Took about 35 minutes..

As soon as we started it it ran smoothly with no missing what-so-ever. Mission accomplished.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Fun with a 4 cylinder engine.

Glad you figured it out.
I've had a couple "fun" four cylinders.
My 90 Olds Quad 4 International Series. 190hp and a 5-speed... fun little four door sleeper. Regret selling it. Especially since gas shot up soon after. Got 30mpg easily.
My current toy is a 85 Mustang SVO with a hopped up turbo four, 5-speed, disc brakes, and lots of mods... Estimated at about 250-275hp. I've had a lot of fun with it the last 15 years or so, but lately electrical gremlins have been keeping me from enjoying it. Old wiring is all cracked and broken and it really needs a whole new harness, which I am very not motivated to tackle.

David
Connect with me on LinkedIn. http://lnkd.in/fY7-QK
Quote: "If it ain't broke, I must not've fixed it good enough"

RE: Fun with a 4 cylinder engine.

Thanks...Interesting in that I read a few online discussions about clogged EGR paths and it was only after reading YOUR explaination did it make sense.

so it is not the plugging of the paths BUT the non uniform plugging.

RE: Fun with a 4 cylinder engine.

(OP)
Car wiring; Blech. I hear you there David.

byrdi; I actually learned that as the ports clog the engine starts to run poorly. As they clog it runs worse and worse until they all clog then the car runs great! It just fails smog testing. :/

Keith Cress
kcress - http://www.flaminsystems.com

RE: Fun with a 4 cylinder engine.

EGR distribution is a big use for CFD work in the original designs. I'm not aware of any of the OEMs running their models with fouled passages though. Maybe they should?

Steve

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