G35 07' sedan - Cold start problem, spits and misfires

[charless82]

Hi

I was wondering if anyone out there had this issue with there engines. When i start the car in the morning after sitting idle overnight the engine spits/sputters and misfires if i touch the excellerator like its choking. after about 1 mins it feels like it finally got some fuel and comes alive! once the car is warm i have no issues. This started when i attempeted to clean the TB and managed to spoil it by moving the plates. Anyways I have changed both TB's, 1 ignition coil and installed the stock intakes back as I had AFE Takeda CAI installed. I have tried giving the car to a tech to reset the ECM but he was unable to do it and the dealer has told me to replace the ECM which cost $1500+ in this part of the world. Any suggestions of what the problem may be ? There are no coeds showing with my little scanner also any suggestions of what scanner i can purchase to read parameters, engine sensor temp etc?

Appreciate any input on this topic.

[gwoods]

This is your only hope. I did the same thing on my 07 G35 sedan after replacing the plugs at 69k and ended up getting new throttle bodies and ECM. Even the Infiniti tech couldn't get my ECM to relearn throttle position after I very very gently cleaned the throttle bodies.

ECU Resetting Procedures

Timing is extremely critical. If it is NOT DONE within the specify time, the ECU will not reset and the Check Engine Light (CEL) will continue to remain ON. A stop watch or an analog clock with a second’s needle will be useful.

Operations Procedures

1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
2. Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.
2a. Fully depress the accelerator pedal (HARD).
2b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the CEL starts blinking.
4. Fully release the accelerator pedal (while the CEL is still blinking)
5. Wait about 10 second.
6. Fully depress the accelerator pedal and keep it for more than 10 seconds.
7. Fully release the accelerator pedal (The CEL light will continue to blink).
8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light should be gone.
If the CEL light continues to remain ON, repeat the above steps. Timing is EXTREMELY critical to resetting the ECU.

Edit: Added the "Easy Method" for ECU Reset

The Easy Method:

After experimenting with different timing, and reading posts by other members, I've come up with a condensed method of doing this reset. This method works EVERY time, even w/o a stopwatch. I've used this method successfully a dozen times, or so, now w/o a watch. After a few times, you won't need a watch or instructions. You'll get so darn good at it, you'll find yourself doing it while waiting at a traffic light.

Timing is not as critical with this method...no stop watch needed. Just count in your head...one-one thousand, two-one thousand, etc, or use stop watch. The most critical step is step #3....wait 10 sec, instead of 7.

1. Ignition "ON", count to 3.
2. Depress/Release pedal 5 times...hard and fast.
3. Count to 10 (not 7!) and fully depress pedal
4. Count to 12 (SES should be blinking), release pedal
5. Count to 10, depress pedal
6. Count to 10, release pedal.
7. Turn off ignition, then start engine. Done!

Accelerator Pedal Release Position Learning

Operation Procedure

1. Make sure that the accelerator pedal is fully released.
2. Turn ignition switch “ON” and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.

Throttle Valve Closed Position Learning

Operation Procedures

1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch is “ON”.
3. Turn ignition switch is “OFF” wait at least 10 seconds.
Make sure that the throttle valve moves during above 10 seconds by confirming the operating sound.

Idle Air Volume Learning (Throttle Position Learning)

It is better to count the time accurately with a clock.

Operation Procedures

1. Perform “Accelerator Pedal Released Position Learning”.
2. Perform “Throttle Valve Closed Position Learning”.
3. Start engine and warm it up to normal operating temperature.
4. Turn ignition switch “OFF” and wait at least 10 seconds.
5. Conform that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
6. Repeat the following (steps 7a, 7b) procedures quickly five times within 5 seconds.
7a. Fully depress the accelerator pedal (HARD)
7b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the Check Engine Light (CEL) stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the CEL is ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure the idle speed and ignition timing are within the specifications.

[charless82]

My tech has tried this a million time but could not get it to work so I assume this means i need to buy a new ECM ? How much do they cost? is the startup fault surely the ecm ? can the old ECM be reflashed by up rev tune ? sorry for all the questions just trying to figure this out. Thanks

[gwoods]

why new get a used one on www.car-part.com match up your vin you'll need to call the wrecking yard and check your vin vs this one a few letters need to be the same.

When you say your tech, is the car at a Nissan/Infinit dealership? If so and they can't get the ECU to learn its toast. I did the same thing, Infiniti gifted me a 100% warrantied repair with new throttle bodies and a new ECU.

[charless82]

They car is GCC spec u think they will still have the ECM? Will a used one work ? The infiniti tech here Don't do the relearn procedure they just replace the part and charge you a bomb. My tech is another guy who specialises in modifying cars and he could do the relearn with a computer hooked up, Don't know whether he tried manually doing it.

[gwoods]

Try the manual relearn sorry don't know what GCC means.

[charless82]

Its gulf specs as I live in bahrain. Will try let's hope it works the rpm now is on 900-1000 is that normal ? The infiniti tech said its high as its supposed to be 750

[gwoods]

750 is normal oh I see. Match up the letters on your VIN and it should work.

[charless82]

Last question when ur running the procedure do you have to do all the steps in on run or can I pause for a bit also do I need to follow it as u have written. I noticed the last bit says to redo 2 of the above steps so does that mean I need to do that all over again ?

[gwoods]

The 'easy method' you can do it with as much time in between as you want. The factory method has to be exact.

I never was able to make it work for mine and finally towed it to the dealership. They tried to recalibrate the Tbodies and flash the ECU neither worked so all parts were replaced.