Jerk under slight load?
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Jerk under slight load?
1996 Bronco Full size. While driving jerk (like someone is pulling on the bumper) No codes. It seems like the over drive is kicking in and out? Sometimes you can feel it at take off. Most noticed at 30-40 mph and 50-55. I have turned OD off, No difference? I am at a loss. AAMCO say I need a whole new transmission. Any Ideas?
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From: Gateway to the West
First of all Welcome to FTE and the Big Bronco Forum. We will do our best to get you the right answers.
The transmission is completely electronic so any faults SHOULD be producing a code. It tends to make one think that the problem is elsewhere. Not that it can't be the tranny just that the tranny fucntions are monitored closely by the computer. Could be a bad front U-joint on the rear DS. If the centering ball/spring go south it causes driveline bind. Have you noticed any vibration or whine as you are coasting (i.e. downhill or any time the driveline would not be under torque) Does the problem seem to manifest itself as the truck is shifting or just after it has? If so, you may have something causing driveline bind under torque but then it releases when the torque on the components changes (i.e. at a shift point).
I realize this doesn't really answer the question but rather poses a few more. But any details could help better diagnose the problem.
The transmission is completely electronic so any faults SHOULD be producing a code. It tends to make one think that the problem is elsewhere. Not that it can't be the tranny just that the tranny fucntions are monitored closely by the computer. Could be a bad front U-joint on the rear DS. If the centering ball/spring go south it causes driveline bind. Have you noticed any vibration or whine as you are coasting (i.e. downhill or any time the driveline would not be under torque) Does the problem seem to manifest itself as the truck is shifting or just after it has? If so, you may have something causing driveline bind under torque but then it releases when the torque on the components changes (i.e. at a shift point).
I realize this doesn't really answer the question but rather poses a few more. But any details could help better diagnose the problem.
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It is consistant at 30-40 and 50-55 more so slight load on a small incline, up hill. Drive shaft in good order, no vibrations, no codes, auto zone checked for pending codes, and none.
recent repairs for emissions egr sensor and vacuum hose, new cap rotor wires, fuel filter. Feels like a tug at rear bumper. All help is greatly appreciated. I added lube guard to transmission. someone said possiable shutter?
recent repairs for emissions egr sensor and vacuum hose, new cap rotor wires, fuel filter. Feels like a tug at rear bumper. All help is greatly appreciated. I added lube guard to transmission. someone said possiable shutter?
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Joined: Sep 2002
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From: Gateway to the West
Both MPH ranges are consistant with the approximate shift point for the OD gearing but if shutting the OD off has no effect on the problem then that shift point is kinda pulled out of the equation here. The only other commonality I can come up with here is the RPM range of the engine. But if there are no power issues with the engine throughout the normal rpm range that doesn't help either unless, under load, the fuel pressure is lacking. The FPR (fuel pressure regulator) is not monitored by the computer (at least not as I recall...96's are ODB-II and I'm not as familiar with that system). Obviously if it feels like the truck hits a wall or is being snagged backward at these points, it may be that under load, the fuel pressure is not great enough to sustain the injectors. You probalby won't be able to reproduce the problem without a load on the engine either. OK, one more question and I'll be at the end of my knowledge for OBD-II systems. Do the RPM's drop when the problem occurs? Does the sudden jerk have a loss of RPM's associated with it? If the truck has a tach, it should be easy enough to tell.
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The rpm's are constant. I really have not noticed a change. I looked at ignition, think that the pick-up could hit, but this distributor is a diffrent style (hall effects). well I guess its time to seek out a fuel pressure guage. hell for the cost for PM I just might install a pump. I did have one time it did not start. I checked spark and scrached my head and it just started. I just may be a fuel pump. I reall appreciate the help. Thanks
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From: Hoboken, NJ...
I would bet my bottom dollar that there are codes, and the monkey at Auto Zone just buggered up the test.
Spend a few bucks and buy a code reader.....then read them yourself.
Then if it needs a new trans....take it to a local Trans ONLY place and have then hook you up with a FULLY updated E4OD.....thats it.
In any case the few bucks you spend on a code reader will be made back the next time you get a CEL........?
Spend a few bucks and buy a code reader.....then read them yourself.
Then if it needs a new trans....take it to a local Trans ONLY place and have then hook you up with a FULLY updated E4OD.....thats it.
In any case the few bucks you spend on a code reader will be made back the next time you get a CEL........?
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Bingo!!!!!!!!
Originally Posted by greystreak92
Both MPH ranges are consistant with the approximate shift point for the OD gearing but if shutting the OD off has no effect on the problem then that shift point is kinda pulled out of the equation here. The only other commonality I can come up with here is the RPM range of the engine. But if there are no power issues with the engine throughout the normal rpm range that doesn't help either unless, under load, the fuel pressure is lacking. The FPR (fuel pressure regulator) is not monitored by the computer (at least not as I recall...96's are ODB-II and I'm not as familiar with that system). Obviously if it feels like the truck hits a wall or is being snagged backward at these points, it may be that under load, the fuel pressure is not great enough to sustain the injectors. You probalby won't be able to reproduce the problem without a load on the engine either. OK, one more question and I'll be at the end of my knowledge for OBD-II systems. Do the RPM's drop when the problem occurs? Does the sudden jerk have a loss of RPM's associated with it? If the truck has a tach, it should be easy enough to tell.
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