Codes 34 and 41 and rough idle
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Codes 34 and 41 and rough idle
New to this forum and think its great! I just inherited a 1989 Olds 98 3.8L from the original owner, SUPER clean car and I want to use it around town but have a rough idle issue I'm trying to tackle.
I pulled codes and get 41 and 34. MAF sensor and Cam position sensor codes? The MAF sensor looks like it has been replaced.
Anyway, it idles rough but seems to accelerate and drive just fine. Anyway to test either of those sensors or any other input would be appreciated.
Car has 241,000 miles on it and everything under the hood looks original(cept the MAF sensor) including hoses, plug wires etc.
Thanks!
I pulled codes and get 41 and 34. MAF sensor and Cam position sensor codes? The MAF sensor looks like it has been replaced.
Anyway, it idles rough but seems to accelerate and drive just fine. Anyway to test either of those sensors or any other input would be appreciated.
Car has 241,000 miles on it and everything under the hood looks original(cept the MAF sensor) including hoses, plug wires etc.
Thanks!
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From: Las Cruces, NM
http://www.troublecodes.net/gm/88-90_38c/
Sounds like you are on track with the meanings of the codes. Assuming the codes are active, and not history codes (you can disconnect battery for a few minutes and see if they come back), they alone could account for your idling issue.
Was the MAF replaced in an attempt to resolve this issue?
Most cases, the MAF sensor wire will break, which can usually be diagnosed by tapping the MAF sensor with the handle of a screwdriver. If the car stalls, it'* likely the issue. Also, these cars have very bad luck with aftermarket units as well. If the MAF was replaced, but the problem remained, it would be good to check wiring, as much of this wiring is in a very hot zone being right above the exhaust crossover.
The most common cause of code 41 is the interrupter magnet breaking out of the housing on the cam sprocket. Take a look over wiring going to the sensor, and then look through the sensor hole with an inspection mirror to make sure the mirror is still intact.
This page gives a good idea what to look for, with pics, and also outlines the quick and easy repair if it is the problem: Simple 3800 Cam Sensor Magnet Replacement - Reatta Owners Journal
Note, the 'proper installation' involves pulling the cam sprocket and inserting the magnet from behind (yes, it'* essentially the labor of replacing a timing chain).
The MAF measures the amount of incoming air. If it'* not working properly, the computer 'guesses' based on a predefined table for fueling and timing.
The cam sensor is used to detect when cylinder #1 is firing to set the proper order for the sequential fuel injection. If the cam signal is not detected, it simply starts the sequential injection at cylinder #1 despite the actual cylinder firing, causing a 5 out of 6 chance that fuel timing will be off, resulting in stuttering and general drivability troubles.
34 There was no MAF signal for over 4 seconds while engine was running.
41 Cam sensor signal was not received by PCM for the last 2 seconds while engine was running.
41 Cam sensor signal was not received by PCM for the last 2 seconds while engine was running.
Was the MAF replaced in an attempt to resolve this issue?
Most cases, the MAF sensor wire will break, which can usually be diagnosed by tapping the MAF sensor with the handle of a screwdriver. If the car stalls, it'* likely the issue. Also, these cars have very bad luck with aftermarket units as well. If the MAF was replaced, but the problem remained, it would be good to check wiring, as much of this wiring is in a very hot zone being right above the exhaust crossover.
The most common cause of code 41 is the interrupter magnet breaking out of the housing on the cam sprocket. Take a look over wiring going to the sensor, and then look through the sensor hole with an inspection mirror to make sure the mirror is still intact.
This page gives a good idea what to look for, with pics, and also outlines the quick and easy repair if it is the problem: Simple 3800 Cam Sensor Magnet Replacement - Reatta Owners Journal
Note, the 'proper installation' involves pulling the cam sprocket and inserting the magnet from behind (yes, it'* essentially the labor of replacing a timing chain).
The MAF measures the amount of incoming air. If it'* not working properly, the computer 'guesses' based on a predefined table for fueling and timing.
The cam sensor is used to detect when cylinder #1 is firing to set the proper order for the sequential fuel injection. If the cam signal is not detected, it simply starts the sequential injection at cylinder #1 despite the actual cylinder firing, causing a 5 out of 6 chance that fuel timing will be off, resulting in stuttering and general drivability troubles.
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rjolly87, thanks for all the great info, I will look at the wiring today. I'm not sure why the MAF sensor was replaced . I pulled the PCM fuse for about two minuets to clear codes and they came back immediately after starting it back up
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Holy mackerel.....241K ? No way those wires are original....if they have the cylinder #'* on them they are......
The rough idles could be caused by the code 41, if not fired in correct sequence....or it could be set secondary ignition components, like plugs, plug wires, coils, possible intake leak....
After market MAF'* are known to be no good right out of the box.....
As for the cam sensor code, could be the sensor, conections at the sensor or ICM, bad harness, or as Rjolly mentioned, missing cam magnet.......the magnet can easily be checked physically, by removing the sensor, and manually rotating the crankshaft bolt, and observing the condition of the magnet....
First pic, missing magnet...
Second, magnet in place.....
If the magnet is ok, then the cam signal can be checked at the ICM, by back probing the appropriate wires....
The rough idles could be caused by the code 41, if not fired in correct sequence....or it could be set secondary ignition components, like plugs, plug wires, coils, possible intake leak....
After market MAF'* are known to be no good right out of the box.....
As for the cam sensor code, could be the sensor, conections at the sensor or ICM, bad harness, or as Rjolly mentioned, missing cam magnet.......the magnet can easily be checked physically, by removing the sensor, and manually rotating the crankshaft bolt, and observing the condition of the magnet....
First pic, missing magnet...
Second, magnet in place.....
If the magnet is ok, then the cam signal can be checked at the ICM, by back probing the appropriate wires....
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Holy mackerel.....241K ? No way those wires are original....if they have the cylinder #'* on them they are......
The rough idles could be caused by the code 41, if not fired in correct sequence....or it could be set secondary ignition components, like plugs, plug wires, coils, possible intake leak....
After market MAF'* are known to be no good right out of the box.....
As for the cam sensor code, could be the sensor, conections at the sensor or ICM, bad harness, or as Rjolly mentioned, missing cam magnet.......the magnet can easily be checked physically, by removing the sensor, and manually rotating the crankshaft bolt, and observing the condition of the magnet....
First pic, missing magnet...
Second, magnet in place.....
If the magnet is ok, then the cam signal can be checked at the ICM, by back probing the appropriate wires....
The rough idles could be caused by the code 41, if not fired in correct sequence....or it could be set secondary ignition components, like plugs, plug wires, coils, possible intake leak....
After market MAF'* are known to be no good right out of the box.....
As for the cam sensor code, could be the sensor, conections at the sensor or ICM, bad harness, or as Rjolly mentioned, missing cam magnet.......the magnet can easily be checked physically, by removing the sensor, and manually rotating the crankshaft bolt, and observing the condition of the magnet....
First pic, missing magnet...
Second, magnet in place.....
If the magnet is ok, then the cam signal can be checked at the ICM, by back probing the appropriate wires....
Yeah, I've had bad results using aftermarket sensors on my 90'* Fords, now I only use Motorcraft when available.
Thanks for the pics!
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