Failed emissions

[bkelley]

Hey,

I live in NJ and own a 2WD 1995 Explorer. Just took it in for an emissions test and it failed. The hydrocarbon count for idle and high idle is way over. Should be 220 for both but are 729/419 respectively. Took it to my trusted mechanic for a recommendation and he told me an engine flush. My truck has over 250k miles on it and I feel that an engine flush will be the death of it. The dealership won't do them if they have over 80k miles for concerns of damaging the engine. Will a full tune up fix the problem?

 

[bkelley]

Let me add, the plugs, oil, and air filter are both new (less than 2000 miles), but the fuel filter, cables and distributor cap haven't been replaced in quite some time. Never for the distributor cap. I've ran a cleaner (Guarantee Emission Pass) twice before the test.

 

[wcjeep]

Which engine?

 

[bluestream1]

HC is from unburned or partially burnt fuel.

HC is generally a sign of misfire, but can also be that the engine is just way too rich. Common causes of HC are:

a rich or lean misfire
a failed O2 sensor
a failed MAF sensor
a failed coolant temperature sensor
a vacuum leak
dirty or sticking injectors
an ignition misfire
old or faulty ignition parts (plugs, wires, coils)
improper crankshaft/ camshaft timing
Improper ignition timing
a failed catalytic converter
a failed secondary air system

You need to trouble shoot these one at a time

 

[RangerX]

This link is older but may still help: http://www.therangerstation.com/tech_library/CaliforniaEmissions.shtml

This line seemed like it could apply to you: -Check your Intake Manifold and vacuum lines for leaks. This can be done easily by spraying lines and edges of intake with Carburetor Cleaner. If you notice a change in your engine's sound, you've probably found a leak. Get these fixed, as they will raise your Hydrocarbons greatly.

Also search the forum, there are other threads over the years of others with emission test troubles.

 

[Flash]

Let me add, the plugs, oil, and air filter are both new (less than 2000 miles), but the fuel filter, cables and distributor cap haven't been replaced in quite some time. Never for the distributor cap. I've ran a cleaner (Guarantee Emission Pass) twice before the test.

First, go get double your money back then do a Seafoam clean.
Go for a hot, hard , high speed run to really clear everything out.

I've heard using an E blend fuel reduces HC at testing.

Turn up for the test with a thoroughly warmed up engine.

 

[bkelley]

Thanks for the replies and excited to be a part of this forum. It's the 4.0L V6 engine. I'm going to replace the ignition coil and wires and start from there. The bare minimum it'll improve my crappy fuel economy.

I'm a fan of seafoam. I've dumped it into the tank before, but never the kind that you put directly in the intake. Once I replace the ignition components I'll give it a whirl.

 

[delexploder]

Before you get into it too far pull the valve cover on the easy side and look hard at the rockers and pushrods, check for vacuum leaks and do the simple stuff first of course but before anything major and before introduction of fluid in the intake ( hydro lock sucks) make sure your valve train is working properly, I've seen several ohv 4.0s that have had this issue , and once the worn rockers and pushrods were replaced they're like new

 

[bkelley]

Quick update,

Changed the ignition coil, spark wires, and fuel filter. Also cleaned the MAF sensor and checked for vacuum leaks (there were none). I think the engine was misfiring as the the old wires were charred inside the boot. Passed emissions and the truck runs great.