1994 Emissions - do not be mad. I already searched.

[batmac2k]

So my questions is for help...
As I seem to pass everything flawlessly, yet somehow did not pass the HC ppm's on idle. I have included the numbers and as far as I am concerned running a little alcohol and/or some injector cleaner for a tank should help me out since I am so close. note that the truck idled a long time while waiting in line.

ideas...

 

[Chris-St Louis]

You have a 14.44-1 AF ratio at idle, and a 14.21-1 af at 2500. You're looking for 14-1

You are actually running a little lean.

 

[batmac2k]

I believe that. but what do you recommend to get me through the test...

 

[Chris-St Louis]

What tests have you done so far? I would look for low fuel pressure, vaccum leaks, and confirm proper timing.

 

[p m]

You have a 14.44-1 AF ratio at idle, and a 14.21-1 af at 2500. You're looking for 14-1

You are actually running a little lean.

Chris, care to explain high HC with running lean?

IME, high HC were due to one of these reasons - plugged up/barely functioning PCV circuit, and worn out oil control rings.

 

[Chris-St Louis]

Ah shit! I got myself confused. He is slightly rich.

Thanks for keeping me honest.

 

[jhmover]

Here's what I got off the net.

Hydrocarbons:

Measured in PPM (parts per million), this is the result of unburned fuel making it out the tailpipe. This is different from the CO problem in that here the fuel has not started combustion at all. This failure is usually caused by an ignition (misfire), or an engine problem such as a bad valve. An engine running too lean will often have excessive HC due to what is called a "lean misfire". Any leaks in the intake system or bad injectors will also cause excessive HC due to uneven fuel distribution.


Sure you don't have a split vacuum hose? Kind of common on Rovers.

FYI I had mine smogged yesterday, it's a 96

IDLE
%C02 15.1
%02 0.0
HC 75
CO% 0.05

2500 RPM
%C02 15.0
%02 0.1
HC 19
CO% 0.08

This is on an engine with 260k on it, I didn't bother to even put in new plugs before the test.

 

[batmac2k]

I did not find much when searching for the pcv circuit. where is the discovery shop manual that used to be on here...

 

[mbrummal]

http://landroverresource.com/

 

[batmac2k]

thanks. reading up on the pcv...

 

[mbrummal]

You should be able to take the hoses off the valve covers and clean out that plastic piece in one of them.

 

[p m]

now let me get back at it...
A collapsed or plugged up PCV circuit would lead to oil leaks, but now that I think about it, it seems to me it would not cause the increase in HC levels.
So, while it is good to make sure it is working, that shouldn't be your problem.

On a 94, you may tweak the ignition timing somewhat (towards earlier).

 

[roverMc]

batmac2k - Do they require emissions tests in Atlanta?

 

[batmac2k]

yes. that is why I am asking... so what should I check next. it just had an oil change. should I do plugs and wires...

 

[mbrummal]

at least plugs. When were the plugs/wires last replaced?

 

[roverMc]

Yeah plugs and wires unless you have replaced them within 24K or so. Do what PM says and check or get a new PCV Valve.

 

[MUSKYMAN]

first thing I would do is check the vacume advance unit on the distributor, I bet it is no longer functioning and you have lost about 5-6* of advance at idle.

I just replaced a unit on a distributor and tested a brand new factory advance unit and 15lbs of vacume produced 5* of advance.

5* of advance will clean up the HC's if the rest of the ignition is working correctly.

 

[p m]

Bingo, I forgot about it.
I've swapped vacuum advance units on all high-mileage Lucas trucks I owned.