Okay to make this short... When i cold start then drive till the car is warm for about 2 miles or 3-4minutes, i will get a pulsing feeling from the car. The RPM's shift about 250RPMs.. This is if i take it easy and hold the gas pedal constant... Seems like a fuel filter, fuel pump or injectors to me.. Any Ideas?

 

If it were a fuel filter, fuel pump or injectors... it would continue when the car was at normal operating temps too.
When you are in open loop mode (cold starts) the engine will hold its shifts longer and does not engage high gear to allow for a faster warm up and light off of the cats. I'm not sure what you mean by pulsing... but the car is running rich and the idle is set higher.. you might be just feeling some of these things as surges..

 

Wasn't there some discussion about the TQ locking / unlocking prior to reaching operating temps, especially in 3 - 5 I think? Could you be feeling the car reach this point and start locking up the TQ for better power transfer? Or is it a a continual 250 rpm shift (in which case yikes!)

 

Okay... well I took the car to the shop, they kept it overnight and they said that they couldn't find anything so I picked up my car and it still hesitates in the morning ( inconsistantly ) I thought i was fine this morning because yesterday they reset the transmission computers and such... but after a minute i came to a stop sign and the car hesitated as i pulled away..

I don't know what i should do.. Do I need to speak to a manager? Do I need to talk to corporate? Another shop? call it a lemon?

All i know is that i dont want to waste 3 hours a day dropping off my car and picking up a loaner for them to tell me that they cant recreate the problem.

And due to my schedule, i can't wait for the the service dept to open so that i can go on a test drive with them.

Help!

 

Wait - is it shuddering, or hesitating? If it just hesitates from a stop, that's interesting; Maximas, the first throttle-by-wire car from Nissan, also had a problem with that. In mine it was fixed by the dealer flashing the ECU (reset plus FW upgrade), and advancing the timing, which is a cool cheap mod anyway; plus the service manager advised me to "drive aggressively" for a while so that ECU memory has that throttle mapping.

 

Hmm.. not really sure what the difference is, but it feels like a quick.. giving it gas then not giving it gas.. it seems to do this when i hold the pedal down at a certain degree while going 20-30mph...

 

Yep, that sounds familiar. Best to take it back to the dealer, mention this previous problems with VQs, and replicate the problem for them.

 

Spoke to the tech on the phone and he said that there was a similiar problem with 06 coupes where they had to reflash the computer (i dont remember which one exactly) So he said he will call the engineers to see if they have heard anything about this and we scheduled for a test drive this weekend...

 

It sounds like this issue goes away one the engine is warmed up. Maybe your car is a little "cold natured" (for lack of better words). I have had cars in the past that surge and act a little strange until they are completely warmed up.

On of my last cars for example was a bolt-on 01 Cobra. I always let it idle until the temp guage moved off of the bottom mark and even then it would fall on its face at anything past 1/4 throttle. Once warmed up however, it ran great and was the fastest car I have owned (so far).

 

Is it hesitation when only applying a little gas? I think we've concluded that when the car is warming up and RPM's are around 2K, the pedal is dead for a certain range, you have to exceed where 2K RPM's would be in order to get a reaction out of the pedal... is that it? I'm thinking that shortly after warm up if you watch the RPM needle it goes through a bouncing motion, as it tries to drop the RPM, goes from 2100-> 1600 -> 1800 and sits, then bounces down to 1000 and back to 1200 and sits there for a but. ultimatly getting down to 700 steady. I wonder if it's this trying to drop and the position of your pedal right around the bouncing RPM mark that might make it studder/hesitate.

Also I recommend starting off in manual mode and shift it yourself.... see if it's the engine or the auto mode on the tranny, I notice auto mode does some goofy things at times. but if you put in DS or M, it's gone.

 

i've found that it's easy to cycle the DBW throttle in this car if you hesitate due to the way this car launches rather than creeps away when you put on some throttle. it's tough to drive this car smoothly. overreacting to a "lurch" will make the car bog.

that said, i also wouldn't eliminate the possibility of something actually being wrong with your car. but throttle/fuel/air issues are way too complex to diagnose over the internet. you have to replicate the condition with a tech and they have to get a computer on there to read what's happening when that occurs. get them to check the wideband O2 sensor output when that happens, too. that way you can identify if it's a fuel mapping issue.