About a week ago, my 90 RS gave me a code 33 (low vacuum at the MAF) so I replaced all the vacuum lines that I could find in the engine. I am going to replace all the intake gaskets also, just haven't had time yet. I haven't had any #33's since though.

Today my car gave me a #13 (lean reading at O2 sensor even at regular engine temp). What might cause that?

My guesses would be: A bad O2 sensor? A leak in the exhaust manifold or pipe before the O2 sensor?

Any help would be appreciated! Thanks

 

bad injector(s), bad O2 sensor?

 

I would replace the o2 sensor. Their cheep for these engines anyway. About 20 bux or so at your local parts place. Hm, I think the hardest part is trying to take the old one off. I would replace that first though. If you still have problems I would check the fuel injectors and maybe have them cleaned.

-Dan

 

OK that sounds like a good plan. I'll try the O2 sensor, although I read in another thread where someone was just having an impossible time getting it out, lol. Sounds like a real PITA.

Thanks for the advice

 

Here is a little tip i know about changing o2 sensors on our cars.

I could NOT get mine out for the longest time. Finally i thought i would start the car and let the exhaust heat up, sure enough, damn thing busted loose right away.

 

I'm getting that code and its due to a leak before the O2 sensor (sensor is almost new). Which in turn is making the engine run more rich than it should.

 

Heh, I don't have any leaks. Yet I have had times where two days later after replacing the sensor, the sensor dies and then the car goes pig rich. Weird, I have had that one happen two times in one week. At the moment running the same sensor I put in a little over a year and a half ago, and still good to go.

-Dan

 

Now there's some great quality control for ya. I hope to have better luck with it.

NHRATA01: Is that leak more likely to be in the engine or the exhaust piping?

 

90RS,
I'd expect that leak to be in the piping somewhere. Might be between the heads/manifolds or the manifolds/ypipe or a piece of piping might have just broken away....if there's a leak, you should be able to hear it from the exhaust pipes close to where the leak is located, tatatatatata.

 

I'm not hearing anything like that, but it does make a hissing sound when I rev the engine. If I lean over the passenger side of the car over the engine I can feel hot air blowing out of the engine compartment. That shouldn't be happening should it? All air should be getting routed through the tailpipe, correct?

 

At the exhaust piping on the passanger side. You can definitely hear a tick, and if you sniff near the manifold, catch a nice drift of raw exhaust. I think one of the studs connecting the pipe to the exhaust manifold snapped and the connection developed a leak there. Not sure what I can do to fix it because the manifold, studs and pipe are all rusted beyond recognition.

 

having hot air do the smack ya in ur face thing isn't necesarily an exhaust leak, this is true because of how hot the exhaust is , even though everyhings gettering routed to the tailpipes, the exhaust gas temps are sky high giving that they've just exited the combustion chamber, and past that the manifolds, engine block, and basically everything else under the hood likes to increase in temp as the engine runs also (heck the hoods are even hot). So, unless ur hearing the ticking, u probably have no exhaust leaking problem. Does sound like u have a vacumn leak however, and you might wanna check that one out, start replacing lines and whatnot, although that probably won't fix ur code 13, it'll help the engine run better, and replace a code that you're engine'll never throw.

 

Not the fact that its hot air, but the fact that it smells like raw exhaust, similiar to when I wasn't running cats on my T/A, that clued me in along with the ticking.

 

I already replaced all the vacuum lines I could find after it threw a code 33 last week. I am going to get a set of intake gaskets and replace them all, I hope that will fix the whistling when I rev it.

 

not to sure on the price, and i should probaly take my own advice on the subject, but you migth want to get vac tester...even though you've already replaced everyline, it still wouldn't be a bad toy to keep around the garage, to ensure that you'll be better equipped to pinpoint a leak in the future.

 

Yeah that's probably a good idea as long as it's not too spendy. I'm sure it would come in handy many times down the road. Thanks for the tips, I'll try to update ya after I replace the gaskets, hopefully that will fix it.

 

I'm curious too. I have a small whistle as well. Yet, I'm still in the middle of replacing some more aging vac lines. Hm, my other thought is that my air pump is whisling a little from it's little inlet. *shrug* Yet, I don't have any codes and the scanner seems to show everything running right when I watch it, so I'm not concerned too much.

-Dan

 

According to the GM Service manual code 13 has nothing to do with injectors and only the O2 sensor. The manual at worst suggests problems could be a faulty O2 sensor or an ECM at worst. Code 13 will set:

-Engine at normal operating temperature.
-At least two minutes engine times after start.
-O2 sensor voltage steady between 0.35 to 0.55 volts.
-Throttle position sensor signal above 4%.
-All conditions must be met for about 60 seconds.
-If the conditions for a Code 13 exist the system will not go "Closed Loop"

It also says to run the car above 1200rpm for those 2 minutes. 1.0 volt is rich and 0.1 is lean for the O2 sensor. I guess it's possible an exhaust leak could cause a problem but I doubt it would throw a code. More than likely an exhaust leak would allow the O2 sensor to read the oxygen levels incorrectly and give you poor fuel economy.