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1970-1995 Range Rover Classic
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136 Posts
Discussion Starter #1
Just failed the emission test. All the levels were good except for hydrocarbons released while idling, and t's 3x's the legal limit. When I got it back from the guy who tested it, a check engine light had came on and its code 48 (IACV), I just replaced it and set the base idle.

I reset the base idle, cleared the code, but I'm thinking that it might be my catalytic converters. Most of the heat shields have rotted off of them. I don't think there's an exhaust leak but they've been rattling quite loudly and I'm starting to think it's fallen apart inside.

My question is what do you guys think? Is there something else that very likely could be the culprit? Is it the cats, and if so anyone know of a Cheaper alternative to the $600 ones that I've seen so far?
 

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1995-2002 Range Rover P38A
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3,952 Posts
High hydrocarbons is a sign of incomplete combustion so could be as simple as worn spark plugs or leads. What is the limit and what did it show? In the UK the limit on something pre August 95 is 1200 parts per million, dropping to 200 ppm for anything newer.
 

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1970-1995 Range Rover Classic
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1,458 Posts
^^x2...When's the last time your RRC had a basic tuneup? Also, was the engine warmed up before the test, at least 20-30 minutes? I always take the RRC for a quick highway drive before any emissions exam.
 

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1970-1995 Range Rover Classic
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136 Posts
Discussion Starter #4
The legal limit is 220ppm and mine was 597ppm.

I had only driven it for 10 minutes and its been cold outside recently. The engine temp at the time of testing was at 166.6°F
I installed a set of champion spark plugs less than 6 months ago and installed a genuine dizzy cap 2 months ago. Haven't changed the leads though, they look decent but I don't know how old they are.

Also noticed that he recorded the RPM at idle. It was at 802, but I noticed that it's been idling so low recently when I'm stuck in traffic.
 

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330 Posts
The rattling you mention is probably the matrix inside the catalytic converter breaking down. If you want confirmation just get under the truck with a long screwdriver and touch the metal end to the cat and the handle to your ear. It the rattle is from the cats you'll know right away.

Now, I know there are those that say the break up of the catalytic convertor is no big deal. (I just read that on another thread) However, there is always the chance that parts of the cat can make their way into your muffler or rear silencer clogging them up and restricting exhaust flow. It's something to be aware of.

Now, if you're looking for cheap replacements and you're not in a state that requires OEM parts, try the Catco 6905. You can get them for well under $100 a piece from places like Summit Racing. They work just fine on either side (I know the originals are different shapes) and will help you to pass emissions in a state that is not terribly restrictive (CA, NY CT, ect.).

If you don't know when the ignition wires were replaced, do it now. Also, if your idle is fluctuating, remove and clean your IACV (stepper motor) along with the part of the plenum the sensor fits into. It should help. I'm taking for granted that you've checked all your hoses for vacuum leaks, ect.
 

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1970-1995 Range Rover Classic
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136 Posts
Discussion Starter #6
Sorry for the delayed response and thank you for your detailed response.

I will give the screwdriver trick a shot, I agree completely and if the matrix is broken apart, I don't want to take any chances. I'll have to do some reading on the restrictions because I live in CT but I still think that I'll be able to use the Catcos.
That is unless you know for sure that I cannot use them in Connecticut.

I'll definitely pick up a new set of HT leads, and I thoroughly cleaned the port for the IACV even though it wasn't bad at all. The IACV is brand new. I have checked for vaccum leaks but will give it another shot today just to be certain.

Thanks again!
 
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