82 OB Hesitation and slow performance after decel
07-08-2015, 03:44 PM
#1
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82 OB Hesitation and slow performance after decel
Have an 82 OB that starts and idles perfectly. When it is driven, however, an issue with hesitation/performance arises. After driving normally and then decelerating, the engine will lug at the stop light and upon acceleration will hesitate and stutter until it will suddenly open up and run normally. At other times, after decelerating, the engine will pull away from the light without stuttering but will require additionally throttle to get up to speed - then suddenly it will open up and take off (as if the engine was having trouble breathing and then opened up to fresh air). The issue seems to occur after deceleration.
Ideas/recommendations are appreciated.
Thanks.
David
1982 928 OB Auto
Ideas/recommendations are appreciated.
Thanks.
David
1982 928 OB Auto
07-08-2015, 09:45 PM
#4
Did the problem develope suddenly, or after you worked under the hood, or over a vast period of time (progressively getting worse)?
Have you ran a couple tanks of fuel through it and the problem still exists? If not, I'd run it down as low as possible and add fresh fuel from a known quality station.
Does the problem develope after it is warmed up or even when it is cold (during driving)?
What type of repairs have you made under the hood lately? Has it been tuned up, complete with wires?
A little history goes a long way when trying the diagnoses things over the net.
Brian.
Have you ran a couple tanks of fuel through it and the problem still exists? If not, I'd run it down as low as possible and add fresh fuel from a known quality station.
Does the problem develope after it is warmed up or even when it is cold (during driving)?
What type of repairs have you made under the hood lately? Has it been tuned up, complete with wires?
A little history goes a long way when trying the diagnoses things over the net.
Brian.
07-08-2015, 10:25 PM
#5
After eliminating any vacuum leak, I would pull the AFM and check the resistance material and wiper arm. These are under the black plastic cover.
My 82 had the exact symptoms and it was due to a worn track in the resistance material and your hesitation could be caused by the resistance material being worn through in certain spots.
The solution is to clean up all the contacts and move the wiper arm about 1 mm back from the original track. This done with a wide blade screwdriver bending the arm back.
There is a tutorial on this procedure on youtube. It is under 944 AFM fix, but the AFM is essential identical to the 928.
After the fix, the car runs fine.
On the bright side, if this doesn't fix the issue and the AFM is toast, 928 International has rebuilt units for under $300 plus core.
My 82 had the exact symptoms and it was due to a worn track in the resistance material and your hesitation could be caused by the resistance material being worn through in certain spots.
The solution is to clean up all the contacts and move the wiper arm about 1 mm back from the original track. This done with a wide blade screwdriver bending the arm back.
There is a tutorial on this procedure on youtube. It is under 944 AFM fix, but the AFM is essential identical to the 928.
After the fix, the car runs fine.
On the bright side, if this doesn't fix the issue and the AFM is toast, 928 International has rebuilt units for under $300 plus core.