Need Diagnostic Help

Shri2222

Need Diagnosis Help.

My Z with 15k miles after being parked for an hr after an hr drive. Runs fine. I have AFR and OPS gauge installed. Smooth idle, revs fine without load, no check engine light, steady AFR 14.1-14.7, all gauges read perfectly.

The car will not accelerate, I have to put my hazards on to merge; it is that slow. It accelerates as if I'm only giving it 15-20% throttle with the pedal floored. It takes about as long as a city bus to get up to speed, and it can not maintain speed uphill. The a/t Trans shifts smoothly in manual mode and seems to shift smoothly in standard as I slowly accelerate and slow. The AFR is perfect, with no sputtering, nothing that indicates a mechanical issue. The car doesn't pull or decelerate unusually either, so there are no stuck calipers.

I tried putting it in cruise control to see if it could maintain 70mph on the highway, but the cruise light just flashed when turned on and would not set cruise.

Does this sound like a pedal position sensor failure? or is it something else?

Spooler

Shut the car off, Unplug the drivers side throttle body and plug it back in and then crank it back up and see if it goes away. If it does, your throttle bodies have an issue and will need to be replaced. Both of them.

Shri2222

And that worked, drove just fine after! Also, why did that work? Trying to learn how this self checks and resets.

Spooler

My car did the exact same thing several years ago. There is an issue with one of the throttle bodies. I just put two brand new ones on it. It would happen on hot days.

Shri2222

Where did you get the replacements? Did you get an aftermarket, reman, or OEM?

Spooler

Brand new Nissan. Don't mess around with aftermarket junk for these. It will have more issues than you want. They were $1200 back in 2019. They may be more now. They may offer Nissan rebuilt.

vtec to vvel

Before you replace the TB's, I would try cleaning them out first as well as the MAF sensors. Also get an OBD II and clear out any codes related to this.

I had a similar issue as well and cleaning them made the limp mode go away.

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BORNGEARHEAD

Find out the codes stored first.

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Spooler

It never throws a check engine light. It has something to do with the throttle bodies getting out of sync. Weak stepper motor or bad board in one of the throttle bodies. Been down this road before.

Tractionless

Maybe try the throttle position relearn procedure as well in the FSM and How-to section here.

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Dreadnaught

I had this exact same issue on my Z. I cleaned both throttle bodies and the issue went away. After I cleaned my throttle bodies I did the 3 resets.

First I had a P0101B. Nissan says to do a PCM recalibration. This fixed the problem for about a year to a year and a half.

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Dreadnaught

My car didn't throw a CEL lights for months until it finally did

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Shri2222

Just an update. I swapped out my Throttle bodies for OEM Hitachis off Amazon for $150 a pop and swapped my accelerator pedal for a salvage touring assembly. All in $350 bucks all in. I also cleaned the mafs and did the throttle relearn and pedal relearn; it drives like new once again. Thanks for all the assistance!