Sudden loss of throttle response on the highway!

wind.zero

I am posting this in the Tuning Section because this problem certainly felt electronic to me. It has happened twice. The first time was one day last week and the second time was about an hour ago on the commute home.

The only way I can describe the problem is a sudden loss of throttle response and what seems like an electronic governor. I wish I could duplicate the problem but I can’t. When it happens again, I will try and get a video assuming I can video and get off the road safely, probably not.

The loss of throttle happened both times while merging from an on-ramp to the freeway. I was traveling about 65 maybe 70 MPH and dropped from 6th to 4th and bam, the engine stops revving at ~4k. The odd part is if I lift off the throttle, the revs stay at ~4k RPM’s. If I floor the throttle, the car barely maintains speed but the tachometer still indicates ~4k RPM’s. I watch the speedometer and the car slowly loses speed with the accelerator all the way on the floor. It is kind of obtuse to describe but losing the throttle on the highway with traffic is not pleasant.

Last week, I was lucky enough to be able to immediately pull off on the shoulder. Today, I had to navigate over a lane of traffic and tried shifting to other gears (5th and 6th), but the engine stayed at ~4k RPM’s and my traveling speed kept dropping even with the throttle floored. It was almost as if the car was coasting even with the throttle pegged.

Last week, I killed the car and on the restart everything appeared to be fine. I was able to rev normally in neutral. I drove on to my destination with no further problem. Today, I had to kill and restart the car three times before the throttle would go over 4k RPM’s in neutral. Before the 3rd restart, I waited about 20 seconds.

Does anyone have any idea what might be causing this? I can’t think of what might trigger an electronic governor or valet type mode when traveling at highway speeds.

The only correlation I can find is speed about 70, down shifting from 6th to 4th and then a sudden loss of throttle response. A restart or several restarts of the car make it go away. After it happened today, I tried to duplicate it and no luck. Nothing has changed on the car, tune, and all gauges/temperatures are in normal operating ranges.

• Water temp is normal right below half on the gauge.
• Oil temp is 200 – 220
• Ambient air temperatures in the low 90’s
• Fuel today and last week was 75% full

Whiskey Tango Foxtrot

nabenson

I would start by seeing if there are any error codes in the ECU. Check your throttle position sensor and anything else that has a part in throttle input..

Cmike2780

I would get your tune checked out ASAP and do a diagnostic. It can't be safe.

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corbin09

I didnt know there were two SC'd Nismos running around? Have you ever been to our Thursday night meet? I bet we could all put our heads together and figure out something. Have you checked for any boost leaks? Is the car boosting fine?

Maybe try to reset the ecu and see if it comes back.

wind.zero

I have already checked for codes using Cipher and retrieved no codes.

Unfortunately, I have only been to 1 of the DFW area meets. During the summer, I have a standing appointment on Thursday evenings. I will try and make another meet in the fall.

I just passed 15k miles so time for an oil, diff, and MT fluid change. I guess I will have my Thomas check out the tune while it is in the shop.

I wish I could duplicate the problem though. Thanks for the replies.

ww77

Bump...
Anything on this??? It happened to me 2 time in 2 laps on Hokenhiem. I have a NISMO as well. Oil temp was under 250.

Osiris

Hey ww77, i have experienced this exact same thing. My car also has an Uprev tune. Actually, i've had this happen on two separate occasions.

First time:
I got check engine lights and other lights came on in the dash. Happened multiple times. Turning car off and on did not help. Had a throttle position sensor code. The fix that time was to replace the throttle body (throttle position sensor).

Second time:
Just as you, no check engine lights or any out of normal guage readings, it just loses power out of nowhere. After turning car off and then back on, the symptoms are gone. After discussing this with my tuner, they informed me that there is a "fix" that can be installed with the Uprev tune. It basically has something to do with the MAF's relaying invalid readings to the ecu and the ecu killing power.

Check with your tuner to get the fix. If anything, get a hold of Uprev, they should have the details on this fix.

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ww77

I am running stock tune with Gen1 intakes, oil cooler and Z1 brake upgrade. After further research it sounds like I had fuel starvation, like a few others on this forum. It happened just as they explained-- After hard right cornering and acceleration. I was running with less than 1/4 tank cornered hard right before the main straight on Hockenhiem and just as I pulled off to the left to power pass and late brake 3 cars in front of me, no throttle so I coasted back until the fuel pump could start pumping again. Could have been dangerous.

wind.zero

^^
This

Mine is at the shop for some routine maintenance and they are tweaking the tune regarding a MAF reading. I will know for sure when I pick it up this afternoon.

My problem was definitely NOT fuel starvation.

ww77

Let me know what they say. I don't know of any Uprev tuners here in Germany. Never had a problem on Nurbergring or on roads, I drive hard everywhere I go. So to speak.

Mshayegan

Hi there,

I have a similar problem where all my lights on the tachometer light up... the abs - traction control & ESP off lights come one. I am driving in first and the throttle wont rev above a certain range. Like 4k revs. I tried to drive with it like this hoping it would reset itself, and it would sometimes jolt giving me power but it stayed like this through most of the gears.

Im guessing this is an ECU/Throttle problem?

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juld0zer

Is this invalid MAF reading issue unique to FI setups or can it happen to NA cars too?
I think i've experienced this sudden loss of throttle response twice now. It never happened prior to Uprev.

The only things i have done in Uprev are the fan control and 2300 throttle curve.

My revs have never gotten stuck at 4000rpm. No lights ever came on and again, no DTCs.
The best way i can describe the sensation is that the CVTC system has locked itself in high-rpm mode and the ecu doesn't realise so it doesnt set a code. The reason i describe it like this is because i put up with the opposite issue several months back. Basically, the motor felt good below 4000rpm and because most of my driving is below 4k with the occasional burst - i never realised until i started to hoof it more often.
From 4000rpm onwards, revs would take forever to climb and it felt flat. Like it had a 4000rpm rev limiter. It would eventually reach redline but it would take an eternity. I believe the CVTC system was stuck in the low-rpm mode.

On both occasions, the motor felt really lethargic below 4000rpm. So i could have my foot to the floor in 1st and the tyres would not spin. I could be in 4th following someone really close at 80kmh with my foot to the floor and not hit them - pretty much. Once it eventually reaches 4500ish rpm, the engine comes alive again but not with the same ferocity as it does normally. Which is why it leads me to think it's the CVTC.

Oil temps were no more than 92*c, coolant less than 88*c, air temp under 23*c - both times. You could also liken it to a high intake air temp lag.

juld0zer

i forgot to add that the first time it happened, it cured itself while driving. I think i just reselected the map. However, i only have 1 map loaded.

this time, i had to pull over and restart the engine to make it normal again.

nomodsjk

Hey man I just had this same problem diagnosed today and it was a damaged throttle body sensor! Check your sensors! Good luck

nomodsjk

Make sure you don't get sold on buying new throttle bodies before checking the sensors. Mine had a obvious Crack. And I had the exact same problems you had so I'm pretty sure this is what's wrong. The diagnosis came from r/t turning in Lansdale PA which is a very reputable shop