Hi all,

Wanted to tap into the collective wisdom here... my 1990 Accord EX is failing its emissions test for high CO%. all the other numbers look OK. Sorry if this is going to be wordy, but I have searched the forum and seen that the best answers come when a good amount of detail is posted.

First, the details:

1990 Accord EX 4 cyl, approx 230K miles. no mods. The car idles OK and runs great, however the CEL light comes on (#1 - O2 content) ONLY when I have been driving at normal speed and then slow down suddenly (either to take a turn or someone in front slows down)... something about that transition from high revs to low in a short period of time triggers that code.

Secondly, here is what I have done to the car:

* new plugs and wires
* valve cover gasket and plug tube seals. (oil was leaking into spark plug holes)
* new PCV valve
* new hose from PCV back to FI rail (old one was worn)
* new catalytic converter (NOx was high, now looks good)
* new O2 sensor (car used to run extremely rough, now runs good)
* looked in distributor cap - the contacts were built up with some corrosive crud which I scraped off - could this be the culprit??
* new injectors/seals/o-rings.
* oil/filter change and topped off coolant

So there we have it.. I have been systematically going through and replacing things which I have found to be either faulty or leaky. i am down to one issue, that is it is running too rich (high CO%) to pass emissions.

for the record, the numbers for CO were:

@1792 RPM: standard = 1.08%, reading was 2.18%
@ 1679 RPM: standard = .98%, reading was 2.09%

What is left??? if it were carburetted, I would have an idea of what to do. should I run hotter plugs? change out the charcoal cannister? EGR?

My instinct tells me perhaps change out the distributor cap and rotor - perhaps I am getting a weak spark.

Thanks!

 

You could try some of the engine cleaner stuff. Seafoam or that "Guaranteed to pass" stuff they sell.

You sound like you might not be into modifications for this car but I always get a waiver from emissions because my car is too low to make it onto the rollers. They don't charge you either.


Modified by Andryzzle at 8:07 AM 5/27/2008

 

hey, thanks for the reply. I actually ran a can of Seafoam thru the injectors at some point. Not sure about the "guaranteed to pass" stuff, do you know what its called?

You are correct, not into mods on this, its actually for my daughter, her first car so if she wants to make mods, she can knock herself out, but i just want it to pass inspection...

I have read also where a faulty MAP or TPS could play into this. not sure about the EGR valve.

 

I bought one of them for my friend the other day at advanced auto parts. The largest thing on the box was exactly that, "Guaranteed to Pass".

 

anyone else run into this?

 

OK I bought some of the stuff I think you were talking about. I asked the guy at Autozone, and he handed it to me from under the register counter, in a winking sorta way

Meanwhile, I replaced the distributor cap (contacts were shot) and checked the ignition timing. It was quite a bit out. Went for a nice blast up the road and back, pulled the plugs, and they look picture perfect... might be time for a little ol retest??

 

I'd say you have a bad O2 Sensor, but here goes......

Hi CO on Driving Test or high Idle Test

Excessively rich mixture due to:

- Carburetor malfunction
- Dirty air filter, faulty choke
- Faulty computerized engine management and/or <U>Oxygen Sensor </U>
- Faulty fuel injection system
- Faulty Thermostatic Air Cleaner (TAC) system
- Defective evaporative canister purge system
- Inoperative or missing catalytic converter
- Faulty or missing air injection system

Hi CO at Idle Test

Excessively rich mixture due to:

- Miss adjusted idle mixture
- Dirty air filter, faulty carburetor or choke
- Faulty computerized engine management and/or <U>Oxygen sensor </U>- Faulty fuel injection
- High fuel electric fuel pump pressure (fuel regulator fault, restricted return line
- Inoperative or missing catalytic converter
- Faulty evaporative canister purge system
You might pull the vacum line off the FPR and see if there is raw gas in it from a ruptured diaphram, but that usually causes a rough idle.

Here's a link about cleaning the EGR ports;
http://img299.imageshack.us/my...7.gif

 

Hi Hondadude -

I did replace the O2 sensor, and things improved remarkably afterward. I dont think the O2 sensor is the problem, but I'll test it.

As from my other thread, i replaced the distributor cap and set the timing (although still shocked i had to move it that much). Not sure about the timing belt.

thing that puzzles me is that the plugs look as perfect a set of plugs I have ever seen, not the usual indication of actually running rich that the readings would indicate.

The tech suggested run some RXP thru and come back after a couple of tanks of gas.

Next step is to check the fuel regulator pressure - since the O2 (code 1) light comes on, but I believe the O2 sensor to be good, the shop manual says check for high fuel pressure as the next step. I suppose the charcoal evap can could be bad?

Anyway, its interesting... thanks for the tips, i'll update the thread, perhaps it will be of use to someone down the line.

 

Just for grins, you might pop off the IACV and blast out the screen with some Berrymans B-12, but at the RPM of the CO test you posted the IACV should be out of the loop.
Sure glad I moved away from Austin before emission testing, they would have a heart attack if I pulled my 85 Yota pickup into a test station.

 

Any thoughts on the RXP stuff? From what I can tell, best to put it in and go thru a couple of tanks before retesting...

dang, thought i had it licked after the timing came back in.