Hi Guys,
I am a newbie here and I have an issue with the the 95 Disco 1 I have.
Basically the vehicle passed the smog on every single criteria with one exception. That of idle speed (725rpm HC) the Co, O2 etc are all well within limits. Where do I start guys? I have a full set of tools etc inc OBD scan tool. But that shows nothing at fault. I am thinking CAT? but then why would the other results be correct? EGR Valve, but again why would every other test be fine?
John

 

There is no EGR.
So whats wrong with the idle speed?
650-750 is dead on for these trucks.
Isn't your truck old enough to not need to be tested?

 

that sounds ridiculous. i had a BMW that failed smog once in CA due to the tip of the exhaust pipe being a bit rusted. everything else passed. gotta love CA.
1975 and older is no smog.
what did the test say the idle should be at? there has to be a high low spec for it.

 

Yup, we live in California....the techs are trained very well these days. They definitely do not want to lose their license.

Post up the entire stats from the report. Running high HC's could be a rich condition, what are the O2 readings?

 

Hi Guys,
The vehicle is a 95 Disco 1.
The Smog numbers that they gave me were as follows.
At idle speed.

CO2 14.30 PASS
02 0.60 PASS
HC 142 (the only problem area they failed the vehicle on. Max allowable HC100 at idle speed) FAIL
CO 0.28 PASS

I still dont get why the rest Idle and 2500rpm range numbers are almost text book perfect and the idle speed HC is off so much.
Thanks for the input guys.
John

 

So its running rich at idle?
I'd start with a tune up, new plugs, wires and cap and rotor.

Where I live we dont have emissions testing or any inspections at all so I dont know how they perform these tests.
So my question is, do they run the engine upto 2500rpm and then let it return idle and check the emissions?
How long do they let it idle before testing after the 2500rpm run? Its going to take a min or so for the idling engine to burn off all of the excess fuel from the 2500rpm run.

 

We don't have emissions testing here either... could this be caused by leaky injectors? I hear that's a pretty common issue on lucas engines.

 

i would recommend taking it to a "gold shield" service place. i had a car that wouldn't pass and took it to one, cost $75 if i recall correctly, and they checked EVERYTHING and gave me what the cause of the failure was, and what other things were not quite right but passing. they are technically the only folks supposed to work on emissions equipment in CA and they are closely watched to not rip you off with uneeded repairs.

 

A couple of things come to mind. High HC at idle with acceptable CO can be caused by:

1. Excessive fuel in the oil, usually when the oil hasn't been changed in a while and the normal blowby builds up fuel in the oil. I've seen vehicles pass after changing the oil.

2. Excessive oil in the PCV system. There is an oil separator in the right valve cover, if you pull the hose that goes from the valve cover to the intake, you should see a little plastic thing sticking out, we used to call that the "pine tree" at the dealer. What it does is separate out the oil from the airstream being drawn into the intake, many times this gets plugged up and an uninformed tech will remove it and not replace it (it also gets forgotten and plugs up causing other problems, but you can tell this is happening if the hose collapses at idle when the engine is running).

Excessive HC can be caused by either too much fuel, or too much oil (they're both carbon based), both of these are easy to check. It may be more serious but I've learned over the years to check the simple stuff first (it's cheaper that way too). Good luck.

 

Any updates?