Power loss after car warms up
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Power loss after car warms up
Hey guys I’ve made a few post recently but I really can’t seem to figure anything out and would appreciate any help. I recently got a timing job done on my 09 g37xS sedan including water pump, guides, chains, thermostat and everything. But I’ve noticed when I first start the car up and drive it drives nicely with full power. But as the car starts heating up and reaches operating temp, there’s a significant decrease in power. I believe the timing of the car is in the right speck otherwise it wouldn’t pull as hard as it does when it’s cold? I’ve been trying to figure out what’s wrong but can’t seem to find any answers :/
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From: DRIVING HIS
Does it work like this?
1. You start the car, begin to drive it.
2. You get on the road, and you're on the throttle lightly just cruising along and you don't move the pedal at all…
3. …car reaches operating temp.
5. Suddenly the throttle input immediately slightly diminishes and the car feels like it bogs down a bit without you having moved the accelerator at all.
I noticed this almost as soon as I bought my car. An Infiniti tech told me that its probably something in the engine tune and couldn't clarify beyond that. It wasn't something he'd heard about before I brought it up either. It's been my experience that letting off the throttle entirely for a second after that lag occurs might help the system relearn the position of the accelerator relative to the openness of the throttle bodies, because the power delivery feels fine to me after I do that. I'm totally speculating about that aspect of this issue though, maybe that's just psychological. Although what I know of ECU air/fuel/throttle management on cold startup versus operating temp might lend some credence to that since less fuel is used once the engine's been brought up to temp. The throttle would naturally feel differently if there's suddenly less fuel in the mix than if the change were more gradual. Maybe it's just really abrupt on VQHRs for some reason.
I've never bothered to have it diagnosed because my engine runs like a top and I get stellar mileage. Don't want to mess up a good thing.
There was an article about cold starts on CarThrottle a few years ago here.
1. You start the car, begin to drive it.
2. You get on the road, and you're on the throttle lightly just cruising along and you don't move the pedal at all…
3. …car reaches operating temp.
5. Suddenly the throttle input immediately slightly diminishes and the car feels like it bogs down a bit without you having moved the accelerator at all.
I noticed this almost as soon as I bought my car. An Infiniti tech told me that its probably something in the engine tune and couldn't clarify beyond that. It wasn't something he'd heard about before I brought it up either. It's been my experience that letting off the throttle entirely for a second after that lag occurs might help the system relearn the position of the accelerator relative to the openness of the throttle bodies, because the power delivery feels fine to me after I do that. I'm totally speculating about that aspect of this issue though, maybe that's just psychological. Although what I know of ECU air/fuel/throttle management on cold startup versus operating temp might lend some credence to that since less fuel is used once the engine's been brought up to temp. The throttle would naturally feel differently if there's suddenly less fuel in the mix than if the change were more gradual. Maybe it's just really abrupt on VQHRs for some reason.
I've never bothered to have it diagnosed because my engine runs like a top and I get stellar mileage. Don't want to mess up a good thing.
There was an article about cold starts on CarThrottle a few years ago here.
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Oct 3, 2016 05:50 PM