UGH- Failed NJ inspection due to HC

[alfisti]

My car failed smog inspection today, due to REALLY high HC.

Idle:
HC: 2597 (220 to pass)
CO%: .11 (1.20 to pass)
CO2%: 6.9
02%: 10.7

High idle:
HC: 1987 (220 to pass)
CO%: .59 (1.20 to pass)
CO2%: 8.1
02%: 9.0

What does this indicate??

The car is an '87 Carrera 3.2, all stock (aftermarket cat, though). 245k miles on it. Previous owner advised engine was rebuilt at 140k miles.

Since I've owned it (1.5 years):
- valves adjusted at 226k miles, and at 240k miles
- New cap and rotor 230k miles
- New plugs 230k miles
- New O2 sensor 230k miles
- New alternator at around 238k miles


Car was stumbling at low RPM, my mechanic found some vacuum leaks and fixed them

Car burns a lot of oil (1qt/600 miles)

Car still doesn't run "well" under 3k RPM. Doesn't stumble on acceleration like it used to, but tends to buck when lifting off throttle. Other than that, it runs VERY strong, and I'm happy with it.

I really would like to avoid changing it to historic registration, as I would like to drive it about 8000-10,000k miles a year. But I'm not ready financially for serious engine work.

Where should I start? I see a lot of threads here, but I'm wondering if the way it's running at low RPM, indicates something specific.

Thanks
-Glenn

[DRACO A5OG]

What is your AFR reading at idle after she is at operating temps of 194F

I passed after I corrected my AFR to 14.7.1

[alfisti]

How can I check my AFR? And then, how to adjust?

Thanks
-Glenn

[DRACO A5OG]

You need an LM1 or LM2 or Better.

The adjustment is under the AFM using a 3MM allen wrench, Right to richen Left to Lean with O2s unplugged.

Then you need to set your base idle to 880RPMS by jumpering & B&C at the engine bay relay socket O2S plugged in.

If you can't borrow the LM1 or LM2. I suggest asking your wrench to adjust it. He should have either of the tools if he is a Porsche shop.

[alfisti]

OK, thanks.

[alfisti]

maybe I can find one of those meters used, or is there a lower cost alternative??

[DRACO A5OG]

When I failed my reading was 15.4. after adjustment to proper levels. she passed Cali Smog ad drove better to boot

[DRACO A5OG]

Try Craigslist for a cheap rental. If you were local I would let you borrow mine.

You can attempt go Ghetto and use a DVM and your O2S as a reader, but it s not accurate as the LM1 or LM2

PMed you

[matthewb0051]

PM sent

[Avanti]

You are running too lean.

With your emissions report you can plug in your numbers into a Lambda calculator here to get an A/F ratio: http://www.smogstats.com/Lambda_CAT.aspx

A Lambda reading of 0 is perfect or stoichiometric 14.7 to1 air to fuel. Over 0 is lean, under is rich.

You need a NOx reading (5 gas analyzer) for this calculator but I plugged in a random 1500 ppm (parts per million) for Nox and got 1.471 A/F ratio which is VERY lean (the ratio doesn't change much with different NOx numbers).

I would say your rough running at low speed is a lean mis-fire caused by a vacuum leak. But the high HC at high RPM can be caused by compression or ignition problems. Unless the vacuum leak is really big but then it probably wouldn't hold an idle. Misfires can also be caused by an extremely rich mixture but you would have very high CO.

Ignition, fuel ratio or compression is the problem. ( Is that all?) Plug(s) could be oil fouled, ignition wire(s) bad, CDI/coil weak, undiscovered vacuum leaks, and also double check the valve adjustment. If one or more are not closing, then you won't get full compression and combustion. Too loose and they won't open enough to allow enough air and fuel in. But you should hear a valve tapping if its that loose.

Your engine has wear and the oil consumption shows that, however, if the compression is still good it should create enough compression to combust to pass an emissions test. Yes, oil burning will cause HC to elevate, but in my experience not this high.

Also, The cat may be bad or weak now due to the oil consumption and raw fuel going through it. How long have you been driving like this? But that usually is not the problem. When cats are bad, usually ALL readings are high, HC, CO and NOx. Your CO2 is very low indicating the fuel is not burning. It should be closer to 15% unless you have air injection and it will be around 13%.

Don't just go and put on a new cat. The cat is the last part to condemn after all other possibilities have been ruled out.

Re- check for vacuum leaks - I use propane, especially in a tight engine bay.
Check wires, plugs and ignition timing
Check compression. ( you could start with a power balance test first if you know how to do it with getting shocked)
Check valve adjustment

[alfisti]

Thanks, that's some useful stuff for me to follow up on.

When you say propane - just spray it around the engine, and see if the idle changes? I have carb cleaner I could use.

Thanks
-Glenn

[Avanti]

Hook a hose to the propane valve so you can go around the areas you may not be able to spray carb cleaner. You don't need the valve wide open. The propane is light and and is "picked up" by a vacuum leak.

Try first with carb cleaner. If the engine smooths out you are lean. If you have a propane bottle and hose, first test would be to insert the hose into the airbox or intake boot after the mass air flow sensor (if equipped) and open the propane valve. If the engine runs smoother then you are lean for sure. What you are doing is adding fuel (propane) to balance the A/F mixture which is lean and has too much air and won't burn. By adding directly into the air cleaner or throttle body, you are compensating for ALL potential vacuum leaks. If you discover you are lean, then "sniff" around the engine with the hose to try and achieve the same engine change to locate the leak. BTW, you can't do the carb cleaner in the airbox or throttle body. Its too heavy to move through the airbox and if put into the throttle body the engine will stall.

Of course, use common sense and safety precautions. Keep the propane away from any flames or ignition sources like fire or sparks. If you see arcing ignition wires don't use it.

[alfisti]

OK, thanks

[patz]

Find vacuum leaks if any, adjust fuel mix using an exhaust analyzer, Co up and HC comes down.

[Jeff NJ]

Go get historic plates if you can. There are no mileage limitations from DMV. With them, you will never have to run it through inspection again, you do not need to use a front plate, and insurance and registration is cheaper.

Of course, that doesn't fix your HC issues, but it does keep you from having to deal with NJ inspections.

[TheSt|G]

Originally Posted by Jeff NJ

Go get historic plates if you can. There are no mileage limitations from DMV. With them, you will never have to run it through inspection again, you do not need to use a front plate, and insurance and registration is cheaper.

Of course, that doesn't fix your HC issues, but it does keep you from having to deal with NJ inspections.

Exactly what I came to post.

[alfisti]

I understand. But that means I can't drive it to work anymore.... the car goes out of everyday use for me. Which is... a bummer. May not be avoidable at this point... but I'd LOVE to keep it on the road for regular use.

[blucille]

Qq or historic tags in NJ won't be a problem, no time of day or usage restrictions per se. 25 years old, no inspections and no annual fees. It's a great deal.

[Avanti]

Get your car to a guy who knows Porsches/fuel systems/emissions and have them fix it. With an HC reading that high, you getting less than 10mpg and overheating your cat which will lead to it melting down and plugging up.

[Driver_X]

Get QQ tags, keep your regular insurance.