Dkelz313

Took car for the emissions inspection today and it failed with high HC levels. I'll post a screenshot of the paperwork with the numbers, but the readings were -->
HC 2.9 - limit is 1.5
CO 8.7 - limit 15.0
NOx 3.4 - limit 3.5
co2 430.9 no limit
The car passed emissions, then it sat for 4 years because i was in another state. So as far as emissions related things I've done to the car before taking it up there, all I've done was seafoam it through the throttle body, put some Lucas fuel injector cleaner in the tank and put some hundreds of miles on it. I thought of changing the oil beforehand but I didn't. The spark plugs wires and everything are new as of 2014/2015 and the car has been sitting since 2016 so they have years on them but not millage.
So with that being said, what could cause high HC levels on a car that's been sitting for years? Where should I start? I have a week that I can take it back and get a free retest.



Thanks in advance.

Schurkey

HC--Hydrocarbon--is unburned fuel.

You don't have a problem with high CO--carbon monoxide--which is PARTIALLY-burned fuel. If your mixture was too rich, you'd have excess CO. CO is a better indicator of rich mixture than HC.

You have misfire perhaps combined with a dead catalytic converter. Any cylinder that doesn't fire, produces no CO but lots of HC. Check the cranking compression of all eight. Verify the plugs, wires, cap 'n' rotor, coil, etc. are all in good condition. Verify that the catalytic converter works, also.

As you're close to the limit on NOx (Oxides of Nitrogen), you might want to have a look at the EGR system. If this were me, I'd run a gallon of water down the intake manifold by pouring a "urine stream" into the intake at ~2000 rpm. Water (steam) does a good job of cleaning the combustion chamber of carbon. Cleaning the chambers could also help with the NOx by reducing combustion temperature. Change oil and filter after using water to clean the chambers, the oil will have lots of moisture in it. Verify that the PCV system works.

Dkelz313

I was going to look at the plugs wires etc today after work. How would i go about verifying the catalytic converter works?
And as for pouring water into the intake, that's through the throttle body right?

Also something else I forgot to mention, when I first started the car afrer sitting for so long there was this STRONG smell of gas and fumes that I could smell from sitting in the driver seat. Would that be an indication of anything, or is that just typical of any car that's been sitting for years? The smell is long gone now though.

Schurkey

Use an "infrared" thermometer. Get under the car, take the temperature of the pipe several inches or a foot AHEAD of the converter. Then take the temperature of the converter itself. The converter should be hotter than the pipe if it's working. If it's the same temperature or cooler, it's probably shot.

If it's a pellet-type converter, smack the muffler with your fist. If it rattles like a maraca, all the beads from the converter have migrated to the muffler. We used to see this frequently. The beads would spit out the tailpipe now and then. I suppose after all these years, you could have an empty converter AND an empty muffler because the beads have been blown out over time.

Yup. Squirt the water in by alternating the left and right throttle plates of a TBI unit. If there's just one throttle plate at the front I suppose you're stuck putting all the water in at the same place and hoping for the best.

Probably nothing unusual. I suspect that you had substantial misfire at first, maybe even rodent nests in the exhaust pipe that had to burn out as the exhaust warmed-up.

Dkelz313

Ok ill give the cat a few whacks to see if I can hear anything and get my hands on a temp reader. I'll probably swap out the pcv valve and egr valve too, but if there were issues with that (including engine misfires) wouldn't the check engine light come on? I have no light.

Schurkey

Measure the temperature of the cat. Whack the muffler.

Dkelz313

Just incase there are codes stored and not showing, I bought the old obd1 gm scanner tool. When it comes in I'll report back if there are codes I need help with.

Dkelz313

Took pcv valve off and rattled it and heard the mechanism moving inside, took off the egr valve to see if it will hold a vacuum and it does, checked the spark plug wires and they're all new from before the car sat. Made sure all vacuum lines were routed correctly.

I checked for codes and see that I have code 44.

afgun

Is it an active CEL with code 44, or a stored code 44 without CEL?

44 is lean, but if your exhaust is rich it suggests maybe a bad O2? Do you have a logger to see what the O2 is doing while you're running?

Dkelz313

It's a stored code without the engine light. But i noticed last night after driving around that if the car sits, either in park or just idling with the foot on the brake the light SOMETIMES comes on - not every time. But once I start driving again after it illuminates it's turns off. So it's pretty much just a stored code.
No, I don't have a logger. Any other ways to check the o2 sensor ?

Schurkey

So libtards can cry and snivel about how much you're contributing to "global warming".

dan5

Is this a 5.0 TPI rather than TBI? (Since this is TBI section)
High HC usually indicates misfire and if CO is low, then lean misfire. Catalyst is likely OK or your numbers would be further out than they are, but you can make the temperature check to be sure. If you have a check engine light blinking on occasion indicating lean mixture, it is likely running lean a substantial part of the time. The old OBD1 diagnostics are a little rough, so when you trip one, it is probably real- especially if it repeats. It is reading the o2 sensor and if it is biased lean and not crossing over to rich in closed loop, it will set lean code. I would start by checking the fuel system for pressure. If pressure is low due to regulator or fuel pump or filter, it will set a lean code (ask me how I know...). You might also have a bad O2 sensor, but I would start with a fuel check. Also, my preference for injector cleaner is Chevron Techron. In my previous experience, it was found to be the best one for cleaning clogged fuel injectors. Others might be OK, but I know that one worked where others tested did not.
If you are running lean, NOx will be elevated some amount as the three way cat wants stoichiometric for maximum efficiency. So, if you get the lean condition fixed, that one ought to come down.
What kind of tool do you have? Can it read data or just codes?

Dkelz313

It is actually the tbi, 5.0.
The fuel pump and filter are relatively new, got them replaced a couple years before the car sat. I'll most likely get some of that techron today anyways. Is it bad to do an emissions test with that in the tank? I plan to go get my free retest tomorrow, and if so then I'll make sure to drive around until I run the tank empty to get it all through the system beforehand.
I was going to check the o2 sensor today, the car isn't at my place so i have to put time aside to go check it out. I was going to make sure the wiring was intact and pull it to see if it looked fouled.
it might be worth noting that I have a vacuum leak, I believe the back of my engine block is warped where it comes in contact with the intake manifold- because it had a surging issue that I couldn't figure out so I took it to a shop and they said the intake gaskets needed to be replaced. The problem still persisted and they couldn't figure it out so took it to another shop and they came to the same conclusion, that the intake manifold gaskets needed to be replaced but upon seeing they were just replaced they said my intake manifold was warped. So bought another intake manifold and the problem is still there so I came to the conclusion that my block itself is warped. So im not sure if that would cause it to occasionally run lean and throw the code 44 in the way that I described due to the leak.
I have a obd2 code reader that tells a lot but its not compatible with obd1. The obd1 scanner I have is the one that only makes the engine light flash and you get the code that way.

dan5

Thanks for confirming the TBI. I thought by '92 they had phased that out on the v8s, but no matter, the principles are the same and the diagnostics are very close.
Code 44 is a lean exhaust. There are trouble trees in my '85 factory manual, but the advice there is that if it is intermittent, to look at other areas than the control system first. Your indication of a vacuum leak is one of those items. A vacuum leak can cause a lean misfire. An O2 sensor could also cause this (it is in the trouble tree), but it also has it's own failure diagnostic that is more likely to set.
Having Techron in the system should not affect the emissions test, it's a very low concentration and it will burn with the fuel. Frankly, if it doesn't pass, I would try to deal with the vacuum leak before spending time an money in other areas. If the manifold is leaking at the gaskets, it either is the manifold (you replaced), a cylinder head, or the gaskets themselves. It shouldn't be the block. If the intake manifold is off, you should be able to check the sealing surface for flatness with a steel straightedge. If it's truly out of flat, the head could be resurfaced on that face to bring it into spec. It would take a hard look to be sure that surfaces are flat and at the correct angle. Sometimes heads do warp on the cylinder face and are resurfaced and the intake flange is not remachined to match. One last thought--has anyone tried to retorque the intake to spec?

Dkelz313

Hopefully I find something wrong with the o2 sensor because everything else that's "easy " to check checks out.
And with the vacuum leak, the camaro actually passed emissions with the same issues. Only difference between now and then is the car being sat outside on the driveway for years. I was planning on just buying a new engine early next year because that surging issue is still there until the car warms up.
After i got the new intake, summer of 2015, I haven't retorqued it or messed with anything under the hood related to that.
I may try and find my old paper work for when it passed to see how much the numbers increased. That may tell me something. But as of now imma just check the o2 sensor, get the techron, seafoam the engine again and see what happens. I should have changed the oil before the test but didn't, but got an oil change, not sure if that would cause high HC with the dirty oil being breathed back into the engine.

dan5

The factory manual suggests that if the code 44 is solid, to check the following:

• Fuel pressure
• Fuel contamination - especially water as "trace amounts near the pickup will cause lean..."
• EGR not opening
• MAP sensor with low output (this one could also be affected by vacuum leak)
• O2 sensor

Schurkey

Means nothing. ONE tank of contaminated fuel could ruin either or both.

The original Techron is good stuff. Shouldn't be a problem. They're now selling several different "formulations" of Techron; and I have no experience with the newer versions.
If you're going to go through the labor to pull the thing out...stuff a new one back in. I'm guessing you have a one-wire sensor, and they're so inexpensive as to be not worth dicking with reusing the old one. An O2 sensor has a definite service life with a long, slow decline, and it's no surprise if they're deteriorating by 50,000 miles. Maybe less.

Should have said that to begin with. Why would you hold-back that info until now?

Perform a cylinder balance test to see if that vacuum leak is responsible for your misfire. Locating/identifying a weak or dead cylinder may give you clues to find the leak. If the intake manifold runner feeding a weak/dead cylinder has a vacuum nipple on it...check the accessory that the nipple provides vacuum to.

I had a pair of dead cylinders on my freshly-rebuilt 5.7L. Turns out the intake gaskets had pushed out-of-position enough that the gasket no longer sealed the manifold where it met the cylinder head. Two cylinders had big air leaks. Several other cylinders had gasket problems, but not bad enough to affect operation. I had used a gasket that had too-large openings for the ports. A replacement gasket set made a world of difference.

Nope.

The problem won't be with the block. Did you use the rubber seals included with the manifold gaskets, or is the manifold sealed to the block with RTV silicone or a similar product? Rubber seals "can" hold the intake up too high so that the gaskets don't seal properly.

TBI base gaskets are also said to be a common problem. Be sure you have the CORRECT gasket to fit your TBI unit.

A code-reader is NOT a SCAN TOOL. Code readers are cheap, consumer-grade junk. Some scan tools are cheap consumer-grade crap, too, but at least you have SOME access to the data stream. A "real" scan tool gives you access to the data stream for engine, computer-controlled transmission, ABS, air bags, computer-driven instrument cluster, body computer (assuming that the vehicle has such components) along with some bi-directional control--the scan tool can command functions as well as report functions. And, yes, a real scan tool will also read "codes" which can be helpful--but the data stream is ESSENTIAL.