Terrible Smog Results HC = 1485 (Std = 400).. Releted to Low CO?

[Rocky_LC]

History:

* Jim C Rebuilt Carb 1.5 Years ago
* Head Redone (Burnt Exhayst Valve) 1.5 Yrs Ago
* Running Good
* 50/50 Mix Gas and E85 at (Current) Test

Smog Test Results (Current)

Test 1st Idle / Precondition * / P-Standard / Final-Idle / Idle Std
HC ppm 1826 / 389 / 300 / 1485 / 400 Fail
CO ppm 0.09 / 0.10 / 3.00 / .13 / 5.00 Pass

* Precondition is Running it on the Dyno at 30 MPH for a Minute. P-Standard is the Limit for that test.

Smog Results - 1 Year Ago (100% Gas - No E-85)

Test Final-Idle / Idle Std
HC ppm 391 / 400 Pass
CO ppm .48 / 5.00 Pass

Is there a correllation between the E-85 and the extremely low CO?

Is there a correllation between extremely low CO and the extremely High HC that can be "balanced"?


Today, I plan to:

1. Tune Up (Air Cleaner / Verify Timing / Plugs)
2. New PCV Valve
3. Compression Check (Dry and Wet)
4. Change Oil


Ideas appreciated.

Rocky

 

[Pin_Head]

1. No.
2. Not really. If it gets too lean to ignite, then you will have low CO and high HC. Your CO numbers are not extremely low.

It is failing at idle and not at whatever "precondition" and "P-standard" is.

High HC means it is misfiring and the fact that it only misfires at idle points to a vacuum leak or a misadjusted idle mixture. Does it idle rough? That would be consistent with misrifing.

 

[FJ40Jim]

CO is decreased by lean running.
HC goes up w/ a very rich or very lean mixture.

E85 is a significantly leaner fuel than RUG.

Conclusion: E85 is driving the mixture too lean, causing lean misfire at idle.

Here's a plot of exhaust gas composition vs mixture:

 

[Rocky_LC]

Pinhead & Jim. Thanks.

* Precondition is running it on the Dyno at 30 MPH for a Minute. P-Standard is the Limit for that test.

Compression Results give me a clue (but not an encouraging one).

Plugs - All Look Good (Grey, w/ Light Dusting of Grey/Brown Ash) #5 had "chunks" on it.

Compression Test Results:

Cyl. / Dry / Wet (Eyedropper of Marvel Mystery Oil)
1 / 135 # / 132 #
2 / 115 # / 114 #
3 / 112 # / 117 #
4 / 105 # / 95 #
5 / 62 / 65 # / 73 # (Did #5 (Dry) Twice)
6 / #135 # / 125 #

Any idea why my "wet" compression is lower than my dry? This seems consistent on my rig.

Going to try and adjust my valves.... Will also continue tuneup and run gas next time...

All Plugs - #1 on Right



No 5.



Thanks -

Rocky

 

[FJ40Jim]

Obviously there is a mechanical defect w/ cylinder #5.

That is gonna make it tough to pass emissions.

 

[Pin_Head]

Yes, #5 is no good.

The other way to get high HC is to have it blow by a leaky exhaust valve on the compression stroke. I tended to discount that possibility since you had just done a valve job. Maybe the valve is just tight, but it doesn't have to be tight long before it burns.

PS a burned or leaky exhaust valve should give high HC at all engine RPM at it looks like you are passing at 30 MPH, but maybe I'm not reading it right.

 

[Rocky_LC]

Jim's chart is not 100% clear to me, but it sure looks to me l- becuase my CO is low and my HC is high,- I must be running on the "lean side" of the graph.

Actually, If I read the chart right, I must be spweing out the O2 and my NO2 is relatively low.

This may be the "greenest" configuraiton I will ever be in!

Jim - What do you think? I have not niticed the trees getting any greener as I drive by (but that would mean I was spewing CO2).....

THanks =

Rocky