2003 I35 with intermittent No Acceleration...

[anitralw]

I have a 2003 Infiniti I35 with about 98k on it. I had my alternator replaced in May of 2008 and just last week was driving when my brake and battery lights came on. I was told that the combination of these 2 lights means that my alternator was going out. Luckily it was still under warranty so we replaced it and the car was fine. 2 days later the car started not responding to the gas pedal intermittently. It first happened when I was slowing down to turn a corner and as I tried to accelerate to complete the turn, the car would not accelerate. It did not shut off, but it was just kind of coasting. It also did it while on the freeway and driving 70 mph. All of a sudden it just started slowing down. (not quickly) but no matter how hard I pressed on the gas or pumped on the gas it would not accelerate. I tapped the brake hard but didn't slam on the brake because I was on the freeway and then went back to the gas pedal and the car picked right back up. It has done this randomly whether the car was cold or hot.

We have replaced the throttle body and the air flow sensor. We also changed out the gas pedal with another briefly today and the problem is still happening.

please tell me someone has a solution to this problem.

Anything helps! and thanks in advance

[loystock]

Looks like the problem may still be with the replacement alternator as a low charging voltage can cause various controllers to behave erratically. You may also have a short circuit somewhere that's dragging down the alternator. Check the wiring to the alternator and the wires from the battery going to the fusible links to see any wires are crossed (and stripped).

With engine running, check charging voltage is 14.1-14.7 VDC. Anything above or below indicates a problem with the internal voltage regulator (or a short circuit somewhere0 of the alternator. If the voltage is low, one or more of the internal rectifiers may have failed or failing. You need to monitor the voltage for extended period and even rev the engine to see if the voltage is fluctuating. (bad)..

[andye]

I have the same problem. Replaced two alternators, new battery two months old, and the brake and battery light come on some times, but not others. Keep checking at Advance Auto whether or not the alternator is putting out power, and whether the battery is good. Always is. Had installation of alternator checked...OK. Last suggestion was that the voltage regulator was bad, but no one knew where it was.

If I stop when the lights come on, turn off the car, and restart, it usually goes off.

I need help.

andye

[loystock]

Welcome to NICO.

As in my earlier posting, the Voltage Regulator is inside the alternator and you will not see it unless you disassemble the alternator.

Non-OEM alternator can be problematic. I have had bad experience with such some time ago where I have to replace the alternator 3 times until I go the right one working.

It's possible that the alternator-battery combination are good but you have a wiring issue in you car. Check for any crossed wire (short circuit) on the battery and alternator wiring as well as in the fusible link area. Have you done any electrical modification in your car? It could be drawing too much current or may have a short circuit as it goes thru the firewall, etc.

Make sure your battery connections are clean and tight. Measure the voltage with engine off - it must be > 12.5 VDC. If not, you have a weak battery, loading the alternator. With the engine running, check the alternator charging voltage is >13.8 VDC and steady (not fluctuating). If the alternator output is low, either the alternator is bad or something is loading it down. To check for abnormal load or short circuit, you need an ammeter (clamp type or series type). With engine off, measure the current drain on the battery (parasitic drain is always present since some controllers need power even with engine off). It should be <50uAmps (0.050 Amp). Anything higher than that requires further investigation of your car's wiring.