2002 I35 wont rev in drive or reverse

[swheeler]

Hello. I have a 2002 I35 that has started giving us a random problem. It will not let you rev the motor above ideal if you are in drive or reverse. When your in neutral it rev's fine. This has happened a few times and I have found that if you put it in neutral and bring the revs just above ideal and then put it in gear it works OK until you let it drop back to ideal, at which time you have to repeat this procedure. After the first couple of times the check engine light came on, so we took it to the dealer. The check engine light was caused by an O2 sensor which they replaced however they could not get it to misbehave while they had it. Now it is still giving us this problem. In addition, the following occurs randomly as well when the above stated problem is happening. The VDC, SLIP and ABS lights start flashing and the lights start shutting on and off and the airbag light comes on and off as well. I would greatly appreciate any thoughts on these problems.

Thanks in advance.

[loystock]

Welcome to NICO.

Make sure your battery connection is clean and tight. Check battery voltage (engine off) is >12.5VDC. With engine running, check alternator charging voltage is >13.8VDC (spec is 14.1-14,7VDC). A failing alternator can give all sort of problems.

If the battery and alternator are good, go to Autozone for a free scan and get a printout of of fault code. If the alternator is good and you have VDC/ABS/SLIP light, first check that your tires are identical size and no excessive wear. If tires are Ok, problem may be due to an ABS relay, wheel sensor, actuator/motor. We can discuss the built-in diagnostic later, if you have that ABS/SLIP/VDC problem.

Again, check the alternator, have a scan and report back.

[swheeler]

Thanks for the information. It started really misbehaving this afternoon so we took it back to the dealer. I will let you all know how it comes out.

[swheeler]

FYI. The dealer is saying that the alternator is going bad which is causing the problems with the dash lights. IN addition, the Mass Flow sensor is going bad, which is causing the problems with acceleration in drive or reverse.

[loystock]

As I have said, a failing alternator can give all sorts of problems. As for the MAF sensor, most of the time, cleaning it is enough to restore its operation. If cleaning did not work, then most likely there is an internal problem within the MAF assembly.

So how much are they charging you for the alternator and MAF sensor replacement? Also ,have them check the drive belt and Idler Pulley while they are on it. After installation, make sure the belt has the right tension. High belt tension will cause the idler pulley Bearing to fail prematurely.

[swheeler]

$1600. They say that the computer has to be reprogrammed as well. We are in a bind with this so we told them to go ahead with the repairs. Does this price sound reasonable? We are being told that a master mechanic is working this problem, so I hope they get the belt tensions right.

[loystock]

Wow...that's a lot of money. OEM parts from Ios (infiniti of Scottsdale) for alternator ($263) and MAF sensor ($449) for a total of $712. Reprogramming is typically $100, and is not needed in most cases (just reset the ECU by disconnecting the battery for at least 30 mins. then drive the car on city streets then highway and the ECU should learn the new MAF parameters).

And if you bought re-furbished parts, the total cost should be <$500 for both. Anyone with basic mechanical skills could have done the alternator and MAF sensor replacement. I even doubt a master tech was assigned to the job. This should be an hour's job, 2 hours at the most.

[swheeler]

The parts ended up being closer to $900.00 and the total bill was a bit under $1600.00. I probably should have looked into doing this on my own, however I was in a bind on time (Had to travel last week for work). Anyway, the good news is that it is running great now. We purchased this car with 50K miles on it and it's now at 153K and this is the first big problem we have had. Overall I love the car, it still looks and runs like a new car which amazes me.

[loystock]

I'm glad to hear your car is up and running again. For as long as you do scheduled maintenance and change fluids regularly, it should take you beyond 200K...easy.