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-   -   HELP! Severe acceleration lag (http://www.the370z.com/engine-drivetrain/91124-help-severe-acceleration-lag.html)

JARblue 01-24-2017 05:51 PM

Yes, IAT = Intake Air Temp. Heat soak is a bitch in this car, especially without a proper oil cooler. There are a number of things you can do to help combat it, but there is no true solution except for driving fast to get some airflow.

The stock intake box and silicone post-MAF tubes are a lot better at insulating intake air from the engine bay heat compared to metal tubes on most aftermarket intakes. The are some DIY mods for older model years with the "fangs" in the front bumper to help get more airflow to the intakes, but ambient temperature only does so much against the heat of the VQ.

A proper oil cooler helps with engine bay temps. As can upgraded radiator and/or fans. A tune can adjust the fans to come on sooner (lower temp) to help stave off heat soak as much as possible.

But the end result is if you drive the car hard its going to get hot. And if you stop while its hot, it is going to heat soak. And high IATs are going to pull timing.

KrnAndy 03-21-2017 05:27 PM

Would love to see if anyone has a solution yet. Same problem as op. Don't think it's heat soak, the problem will go away mid drive occasionally (even sitting at a stop to induce heat soak)

JARblue 03-22-2017 08:48 AM

Quote:

Originally Posted by KrnAndy (Post 3630412)
Would love to see if anyone has a solution yet. Same problem as op. Don't think it's heat soak, the problem will go away mid drive occasionally (even sitting at a stop to induce heat soak)

You're saying you drove it hard to get the temps up high and then sat stopped to induce heat soak and could not replicate the acceleration lag? Sounds like you just didn't heat it up enough for the ECU to pull timing, but if it was doing it earlier on the drive when the car was cooler and then didn't do it when you stopped to induce heat soak, you might be right that it's not temperature related. Are you monitoring IATs at all?

Datsun Z 03-23-2017 02:05 AM

My issue was fixed with a throttle body clean. After that my car ran great. So far so good.

VKNismo 03-29-2017 07:45 AM

I had a similar problem. My car also died on me a few times, while idling and coming to a stop. I thought it was my fuel pump but it turned out to be my throttle body. Problem resolved after I clean the throttle body.

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KrnAndy 03-30-2017 02:24 AM

Quote:

Originally Posted by JARblue (Post 3630649)
You're saying you drove it hard to get the temps up high and then sat stopped to induce heat soak and could not replicate the acceleration lag? Sounds like you just didn't heat it up enough for the ECU to pull timing, but if it was doing it earlier on the drive when the car was cooler and then didn't do it when you stopped to induce heat soak, you might be right that it's not temperature related. Are you monitoring IATs at all?

I never drive the car too hard at all anymore, but the problem usually arises during normal driving conditions when oil temps are at normal operating temps around 180-200

Not saying it was the most accurate research, but the problem could come up after a hard pull, waiting just a second at the stop, then going, and then the problem could not even happen after a few hard pulls, and sitting at the stop for a bit with a toasty engine. I read a few other threads about a brake switch problem, thought maybe it could be the problem but it happens when i come to a very hard stop, or my engine temps are warmed up. feels like the car is starting from 3rd gear, my friends 370 feels way different, he was confused too!

conclusion is from reading over a hundred pages from different threads in this forums is

brake switch, brake booster sensor, MAP (manifold pressure sensor), timing being pulled? (inconsistent so idk)

already cleaned mafs, im on stock intake boxes, throttle bodies were taken off to look at the back side and in to see if there was any build up, but looked pretty clean to me, didn't want to have to do a relearn by manually opening the valves.

i just don't know any tbh, the 350z and g35 i had before pulled really nicely regardless.

im at a loss, the 370z is a great car but i can't figure this one out.

jchammond 03-30-2017 03:24 AM

Un-sure if this would help; but i deleted my coolant hoses that flow through the throttle bodies....they are there to prevent icing up in very cold condition's.
There is a thread on this....unsure of performance gain's/losses....but definitely run's fine in cold weather.
I had a recent glitch in mine (2 week's ago) where it wouldn't rev past 6500k or so (wot) & felt like is was stumbling....manually shifted to next gear & same thing.
check'd all hoses,connection's & even purged a fuel sample from rail....all looked good;put back together & run's fine....???
Hope that doesn't come back,,,but wasin a bit of traffic that day & oil temp was around 200*,,,ambient temp was 70'ish

jchammond 03-30-2017 03:31 AM

My next step was to install fuel block & fuel pressure gauge/as I thought maybe pump was getting weak...but this is where the rpm's peaked in 2nd & manually up shifted to 3rd...same thing. And was stuttering & weak.
3/17/17'https://uploads.tapatalk-cdn.com/201...442e668fce.jpg
About 600 miles ago.
poor picture quality is from the vibration from the stuttering....as this happened on a Friday & had me sick all weekend running test's on it.


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