Possible cat problem?

1991 buick regal Custom 3.8....

Codes i have pulled as of 7 pm tonight.
42 The EST signal did not change when the ECM applied bypass voltage to the ignition module.
23 Inlet air temperature sensor signal showed an air temperature of -29� F for 4 seconds.
41 Cam sensor signal was not received by PCM for the last 5 seconds while engine was running.

1) whats EST mean? and how do i fix the code 42? thats the first time ive ever seen that code...

Cleared codes and 23 went away, but im not worried about that. Car runs like dog meat, agian. Repalced the Ignition control module to cover that ground. Swaped out packs to cover that. plugs and wires got done. previously cam sensor and crank sensor got replaced. Now I've read around the regal forum for a bit, and it sounds like my catty is like smoked. Car misses at an idle, and you can hear it backfire during acceleration (any type of acceleration, esp. when its floored). and its not a poof sound, its more of a snap or pop, and i can hear it over my 2 15" subs, and the 2 400 watt amps, when the stereos about half cranked). if i have the car in 2nd gear ( i know how wonderfull that is for the tranny) and i do the speed limit (at about 3 grand plus rpms), it doesnt miss/backfire as harsh. happens 10x worse when the motor is hot.
2) So minus for the cam sensor code, i know what i have to do for that.. *Sigh*... could the cat be the source of the majority of my problems?
Thanks,
Bill

Ok here we go. The code 23 issue is inexpensive and easy to correct by replacing the sensor. Codes 41 and 42 are probably related. The EST concerns electronic spark timing (ignition control circuit). Check the cam position sensor and the ignition module. My book says to check the wiring connections and the cam position sensor for a missing magnet. If you pull the cam sensor I would just go ahead and replace it to be sure. The ignition module relies on the cps to fire the coils at the proper time so that may be the entire issue.

As for the cat. it is possible that it is plugged or partially so. Pull the pipe and check to see if it is blocked or broken up, you can also tap on the cat lightly to see if it makes a rattling sound if so it is gone. They are not expensive to change today so remove it an put a new one on. I hope this helps!

Replaced the cat, the cat was fine...well old and rusty, but still looked like it was there. Minus for the new cat smell, nothing changed. I went and purchesed a pcv valve, and to quote autozone "PCV VALVE

On your 1991 BUICK REGAL, the PCV VALVE is:


UNDER HOOD, CENTER, UPPER ENGINE AREA, TOP OF ENGINE,
MOUNTED IN PASSENGER SIDE OF INTAKE MANIFOLD

"
Unhuh..... Yeah i dont see it. The Pcv valve i was given is a short straight cylndrical one. and i purchesed a map sensor, which apperently these cars dont have one. Camshaft sensor is good, along with the crank sensor. I believe the magnet may be broken, i still have to get around to fixing that. If there is a map sensor, wouldnt it be on the passengers side firewall? and the pcv valve should be in the valve cover, right? lol.......... i read in another forum that the 3.1's had it under the pheylum (forgive me for the spelling). What is that?
and weres the map/maf at? maf should be in the throttle body, right?
Thanks,
Bill

It depends on the model but yes it should be on the throttle body. On the 3.8 the PCV is located on the end of the phlenum. That is the black thing in the center of the engine. The PCV is located under the MAP sensor that is located on the passenger side of the car at the end of the phlenum. Remove the MAP sensor and the PCV can then be removed.

Wow, that was complicated. lol. I finally found the pcv valve. It was on thepassengers side like you said. I found it inbetween the power steering pump and alternator. it was under a black plate, at the end of the upper intake manifold. Now i gotta locate the map sensor. Its not near the throttle body.... the throttle bodys on the drivers side of the car, along with the tps or throttle positions switch... is there a possibilty the map is behind the plastic sheet on the firewall? I must say though, the pcv didnt solve all my problems, but it sure did fix the rough idleing in park. still got the problem in drive/reverse though.

Sidenote. I know that on newer vehicles, if the battery is low, sensors and stuff will go haywire. could my battery be weak enough to weres its only effecting those coupld of sensors?

Thanks,
Bill

On earlier model vehicles like yours the MAP sensor was located on the firewall. It should be easy to see, looks like a small rectangular box about 2.5inches long with a vacuum line and electical connector.

Right, i know that; i have seen it and replaced it on my Roadmaster. I do not see it anywere in my car, nor do i see it in the All Data Components location guide. Is it possible i only have a maf sensor in this vehicle?
Thanks,
Bill