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Online Wrench
Online Wrench, ASE Certified Technician
Category: Car
Satisfied Customers: 402
Experience:  ASE Certified, Asian and Domestic Specialist
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2001 hyundai: v6 auto..shifts erratically, surges sometimes..warm

Customer Question

2001 hyundai 2.5 v6 auto, holds shifts to long, shifts erratically, surges sometimes. More noticeable when car is cold, but does it warm too. No codes. Speed input and output sensors replaced about 10k miles ago, but code had indicated problem with them. Problems seem similar to that problem but will not throw code. Car starts fine but will rev in neutral sometimes, more so when cold.
Submitted: 8 years ago via
Category: Car
Expert:  mike replied 8 years ago.
Hi how many miles ???? How tranny flush services have been performed?? How many fuel induction services have been performed?? Thanks mike
Customer: replied 8 years ago.

Hey Mike,

125k miles, fluid is up in the tranny but never been flushed to my knowledge. Not sure what a fuel induction service is but sure i never paid for one. Car seems to run very tight and has good power. Just can't seem to shift the way it is supposed to. Doesn't seem to miss a shift, just holds the gears to long.

Expert:  mike replied 8 years ago.
Hi the tranny flush and induction service is done every 30k. But we will focus on trans. Yeah every 30k should have flush. removes and adds 12 quarts of fluid. I would recommend going somewhere that does a flush service and not just a drain and fill. That only changes maybe 4 quarts. Just had one the other day with 68k complaining of transmission issues. Performed flush and there is a sight glass and the fluid was black. Does not look black on stick but was very very dark in machine. There are a couple of service bullintens for this concern but that was back in 2002 so im sure that would not be it. But it needs to be at dealer and hooked to their scan tool to diagnosis the service bulletin. I would get a service done first. Mike
Customer: replied 8 years ago.

Hi Mike,

While I don't think it is ever a bad idea to flush the transmission....i don't think this would explain the surging or reving while in park?? I hope i put that in my original question but that is part of the symptoms. Revs in park, mostly when cold, surges sometimes at speed. If you disagree let me know and I'll start with the flush regardless, it can't hurt. Thx--Dan

Expert:  Online Wrench replied 8 years ago.
HiCustomer It sounds to me like you might have a bad Throttle position sensor. The TPS and the output speed sensor is what the computer uses to calculate shift points. I had a hyundai with a bad tps that caused idle fluctuation, delayed shifts, and surging without setting a code. Try un-plugging the sensor and see if this makes a difference with the issue. If it takes away the surging and delayed shifts, suspect a tps. Shifts will seem short due to it shifting of a pre-calculated value. If you have any questions I will be glad to assist you. P.S. Service that trans too.
Online Wrench, ASE Certified Technician
Category: Car
Satisfied Customers: 402
Experience: ASE Certified, Asian and Domestic Specialist
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Expert:  mike replied 8 years ago.
Hi yes I do notice that you said about it reving and surging. Yeah Like the person that butted in said I would look at the tps sensor. Mike

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