iv been workin on this car of mine for about 3 years the car for the most part. i ran through inspections in 2008 the first time before most of the work and of course it failed for a multitude of reasons.fixed em all. or so i thought. just went through bout 2 hours ago and in the middle of it the idiot testing my car decided to ignore me when i told him about the fan switch. well apparently NJ has a high and low idle emissions test. overheated. well they didnt pass me needles to say but what i was wondering is if the car overheated would that raise the hydra carbon levels in my exhaust.

sorry for the long description but it pissed me off.
passed for everythin else

 

High temp tends to lower hydrocarbons, but probably not enough to pass or fail.

What induction do you have? You say you've been working on it, how fresh are the ignition system components? Factory computer control, or has it been modified? If factory, how fresh is your O2 sensor? Can we assume you have a cat in the exhaust?

 

it is a 5.0 with the tpi, full exhaust, brand new cats, 02 sensors are not stock but i have no clue how old it is. engine is completly stock. all the emissions were just repaired. the car hasnt passed inspection since around 2004.
the inspection reads
HC ppm at idle is 1874. the standard is 220
HC ppm at high idle is 583. the standard is 220
everything else passed

thank you

 

Hello camaroz2887!!

I would replace the O2 sensor, they don't last forever, and if it's not stock, it may not even be working properly for your car!!

High HC's are caused by overly rich fuel mixtures, caused by a faulty O2 sensor!!!

 

that makes sense if the o2 sensors cant read the amount in the exhaust it cant compensate.
thank you

 

check your timing and check your EGR as well... does your car have a hesitation or stumble when you tap the gas? ...

 

running rich can cause high HC, but so can running lean.
also, a misfire, vacuum leak, timing off, fuel pressure or low compression are some other things that can cause high HC.

what are the O2, CO, and CO2 numbers?

 

low idle
CO%-.34
CO2%.11.47
02%-3.99
high idle
CO%-.71 .34
CO2%-13.18
02%-1.57 .
it does stumble slightly. i still cannot find a thread showing what timing i need to set it at exactly. of course chilton's manuel didnt help at all.

 

If you have the radiator fan on a manual switch, either temporarily wire it up to ignition hot, or call Painless Wiring and order whatever it takes to return the fans to automatic operation.

 

over advanced timing will produce these results.you a little rich but you definetly have a lot of unburned fuel there.fix your stumble and youll pass i/m

 

are you running factory TPI or factory Carb? you can sign up on autozone.com and it will give you that information...

and that stumble could be an EGR problem... you will have to perform a few test to pinpoint which area of the EGR system is faulty... either the solenoid, the EGR valve itself, a clogged EGR port, or perhaps if equipped the EGR temp sensor...

 

Base Timing should be set at 6* BTDC with the ESC Disconnected (single wire connector sticking out of wiring harness over by the blower motor)

 

the Z28 came with FI only?

 

with the numbers you have and using a lambda calculator, you show to be running lean.
the AIR injection adding fresh air to the exhaust does have an effect when using a lambda calculator, so you may still be ok.

the EGR valve leaking a little at idle will cause high HC.
if the motor isn't running fast enough with enough throttle, it can also cause high HC at a fast idle.
normally if the EGR valve is leaking at idle, the motor will have a rough idle or run very badly, but not always.

another thing to check is the injectors.
do an ohm test on them both hot and cold with a DVOM.
if you still have the factory injectors, they could very well be clogged.
the factory injectors weren't the best designed.
back when thirdgens were new, it was common to find dirty injectors on motors with 20~30,000 miles that the cleaners available back then wouldn't clean.
without the right equipment, there really isn't a way to check the flow of the injectors on the car.
intake valve deposits can also cause emissions and driveablity problems.

 

Depends on the year, in 85 you could get a carbed IROC.

He has an 87 305 TPI

 

i have the 02 sensors on order. just in case they prob should b replaced. i have the timing set to 6* btdc. but how would i test for an egr leak. would i hear it or feel it?