High Hydrocarbons
 

Hi All,

Wouold appreciate any thoughts/advise on what I quess could be a problem.

Took my 86 for emmissions inspection and it passed, but barely.

Results were:
HCppm: @15rpm 129 (limit 135) @25rpm 130 (limit 130)
Co @15rpm 0.31 (limit0.76) @25 rpm 0.45 (limit 0.80)
NOppm @15rpm533 (limit 1052) @25rpm 477 (limit 957)

Do I need to start freaking about my mixture being too high with chance of ruining my engine !?

Different posts suggest the Oxygen sensor but that it could be anything to do with the Motronic system.

I have had the car 2 months (how time flies), bought in TX and maintenance records show TX inspection about 1 yr ago with very low hydrocarbons. Wonder what happened. The car has a Autothority chip.

Do you tink I need to take it to a shop to have them check the settings ?
Any recommendations ?

Thanks

George

I doubt it's the cat because I think everything would be high. I would check the mix.

It could very well be the upgraded chip....did the PO give you the original. You could have swapped it out prior to your inspection....next time.

Did you warm the engine and exhaust good and hot prior to the test? A good 'spirited' drive prior to help blow/clean things out probably a good idea.

There is a switch on the DME for different a/f mix settings/mappings.
http://forums.pelicanparts.com/showt...me+fuel+switch

Also check to make sure the O2 sensor is plugged in. The car will run in 'limp home mode' if unplugged. LHM mode is probably a richer mix to ensure no detonation.

Faulty head temp sensor could be fooling the DME to think the engine is still cold.

Well, since you passed, it's time to buy that Fabspeed Euro pre-muffler and enjoy the boost and low-end growl for two more years. For your next inspection, put the original chip back in, put the cat on and get it orange hot before you go to the station - or get a P.O. Box in Clarke Co.

Thanks guys.

It had the peformance chip when inspected and I did run it for 40 min with oil temp as high as I have seen it go.

A new DME relay was installed recently. Perhaps it could be responsible.

There is plenty of power and it definately doesnt 'limp home' so my guess is the oxygen sensor is connected, although I think it is original.

I am curious to feel the difference with the original chip and I think I may install it to see the ditterence.

At which point is a rich mixture a problem (bad for the engine) and how do you know you are at that point ?

I'd go ahead and replace the O2 sensor. If you passed emissions, you're definitely safe as far as mixture goes. If your gas mileage starts to really suck, your exhaust smells like an Evinrude outboard motor, you can't get your car to operating temperature, you change your oil and it smells like gasoline, THEN you have a problem. Stop worrying, get your brakes done and enjoy the car.