'84 Monte Carlo (229 V6) -- oxygen sensor

[justinowen]

Hi everyone,

I got a fault code 45 ("Rich Exhaust") on my '84 Monte Carlo (229 V6). I'm going to replace the o2 sensor. I found 1 just upstream of the catalytic converter but I wanted to make sure that is the only one.
Can someone with a similar car (or shop manual) confirm that is the only one?
I ordered a shop manual but it is still on the way.

Thanks,
Justin

 

[jcelk]

there is only one 02 sensor that may not fix it .make sure the choke is opening up that would set that code doe;s it run ok ? are there any other codes ? do you hear the mixture control solenoid thats in the carb clicking ? has anyone messed with the carb lately ?

 

[justinowen]

there is only one 02 sensor that may not fix it .make sure the choke is opening up that would set that code doe;s it run ok ? are there any other codes ? do you hear the mixture control solenoid thats in the carb clicking ? has anyone messed with the carb lately ?

Thanks, jcelk.

It idles rough and it hesitates initially when the accelerator is pressed. That was the only code. I don't think the carb has been messed with lately.
When I had the jumper in (to get the fault codes) with the ignition switch in the ON position I did hear a click/scratch sound every few seconds -- and I don't hear that sound with the ignition switch in the ON position with no jumper installed.

I was just looking at carb rebuild kits. I just got this car but it is likely no one has tuned this carb in many years.

 

[justinowen]

Oh, also, the check engine light came on only for about 1 minute after I had been at 55 mph for 15 minutes.
It turned off once I got on a side road (35 mph).
This was while I was driving it back home right after I bought it.

 

[ELCAM]

You might also consider a clogged catalytic converter.

 

[jcelk]

you should hear the clicking sound with the hood open when it;s idling don;t mess with the carb unless you know what you are doing it;s computor controlled ..check that choke make sure it;s open when warmed up

 

[justinowen]

Update:

I did a vacuum check.
Stead ~20 inches of mercury at high idle (on a cold start).
After it is warm the engine idles at such a low RPM (not very smooth) vac drops to 15 inches of mercury and bounces around there.

Choke check looks fine.
Mostly closed on cold start and slowly open as engine warms then fully open once up to temperature.

EGR valve check seems fine.
While idling, when I actuate value (by pressing up from underneath) the RPM drops. When I let go the RPM rises.

Other symptoms:
- Smokey exhaust
- Carbon dust (that i can wipe up) under the tail pipe after an engine run

Today I am getting a PCV value and other routine maintenance items (since I don't have records for the last time these items were changed):
fuel filter, PCV filter, air filter, EVAP canister filter, o2 sensor.

Any other recommendations?
I am considering: timing check, plugs, wires, points check?

 

[69hurstolds]

I HIGHLY (circle that and underline it) HIGHLY suggest if you can find an olds-school ACDelco AFS-16P or AFS-20, or AFS-21 oxygen sensor, use one of those instead of a generic aftermarket unit. They changed O2 sensor GM part numbers like I changed underwear, about once a month, so there may be a handful of GM part numbers for each, although the Delco p/n doesn't change. 🙂

Those work the best right out of the package in my experience. Whatever you do, don't get a Bosch. They suck.

Here's an ebay one for not a ton of cash.

ACDelco # AFS-20 Oxygen Sensor GM # 25162693 - Made in USA - Sealed in package. | eBay

This ACDelco # AFS-20 Oxygen Sensor GM # 25162693 is a high-quality part made in the United States. It is designed to fit lower placement on vehicles and is wired with blade and bullet terminal types. This sensor is a direct fit with easy installation features, making it a great choice for car...

www.ebay.com

 

[69hurstolds]

You have no points in your distributor as by 1984, it was all electronic.

There's only ONE O2 sensor on your car. Or as it came from the factory. The above O2 sensor parts were the ones listed for everything but the 4.3L. You said yours was a 229 (3.8L) so it should be one of the parts mentioned previously.

Your mixture control solenoid could be sticking, but it's hard to say if you're not getting any other code than 45. EGR solenoid maybe? Is it working right? Does vacuum open it when it's needed? Just because the valve moves manually doesn't mean it's working. Once you get your manual, it will help you immensely.

This is a code 45 trouble shooting guide for an 86 Monte Carlo, however, it's likely to be the same as your 84.

 

[jcelk]

i guess black smoke that would be it;s running rich if the computer is not working the mixture control solenoid will stay open allowing to much fuel or the float in the carb is malfuntioning allowing to much fuel...check if you hear the mixture control solenoid clicking when idling that will tell you if the computer is working at all