Thread: Launch control cutting my rpm randomly

I'm having problems with my NX. It's hard to start, it's almost like it's getting told by the ECU to cut fuel.

I suspect the launch control.

-During a WOT run, it was like launch control cut my RPM when I hit 4k rpm. Had to enable, disable it and redownload.
-When the car is hard to start, the rpm needle shows 1500rpm with key in ON position.
-If I disable launch control completely, I sometimes cannot start the car. Wat. I have to enable launch control to start it. (Great theft deterrant )

Am I doing something wrong? This is my settings, and a screenshot of a log where it kicked in at wrong time:


It's like it was thinking that my speed was 0, so it kicked in?

I could live without launch control, but then I can't start the car Really lost with this...

Try disabling the "Enable Set Launch" check box .. that way you can't inadvertently set the limiter so low that it won't allow the car to start or move.

If the speed is dropping to zero then that is a cluster or wiring issue.. the ECU gets the vss signal from the cluster.

To disable launch control completely you can set the "LAUNCH MAX SPEED" parameter to 0.

Thanks, I will try that. Just remembered that I got "Code 11 - Crank Angle Sensor " two weeks ago, but I haven't gotten that code since. It's probably my distributor or wiring that is at fault here. Just another day using a 23-year old car

Just keep me posted if you need any help.

You are also welcome to shoot me over an email with a TCL during cranking and your current TCD and I can check it over for you.

Thanks for the offer, I like to try to solve things myself, but I will resort to sending it to you if it's an emergency NEMU is so user friendly

@Dala

Did you figure out the issue? My car started doing this also.

A little while ago you posted something about having an issue with the set launch rpm on the tach on cold starts. My car also does this. Im going to assume our problem is the same.

Woah, let's solve this together then!

I'm assuming that my mishap with the launch control activating in second gear was due to that I uploaded a .tcd with the key on the ON-position. Maybe it went corrupt? After uploading it again it didn't happen again... Hoping it was just a fluke!

The cold start problem is still present. If the car is left in the cold for more than 12 hours approx, it's really hard to start. The launch control application shows 1500rpm when I am trying to cold start. It always starts OK after two or three tries. If it happens to start on the first, it is limited to 1500rpm, and impossible to move, since it cuts igition if you try to rev it over 1500. Shutting it down and restarting it always solves this.

It's like it's forgetting what the launch rpm should be. Like a condensator runs out of juice after 12 hours, and messes up the coldstarts :P

OnTheChip said:
"If you don't have 12V at ECU pin 46 at all times, the ECU will "forget" the "set launch" rpm setting and revert back to the default launch rpm setting on the Nismotronic LIMITERS, REV LIMIT SETUP screen."

But shouldn't it revert to my preffered launch rpm then? 4000? Where does the 1500 come from? Oh, and trying to set it manually with the pedal does nothing!

It might be:
-Bad wiring?
-Bad distributor?(took mine apart, almost no oil in it)
-Bad ECU? What does the battery on the NEMU keep track of? Some condensator might lose voltage?
-No voltage at pin 46 after letting it sit

I'll tell you how it progresses, tell me if you found something!

Sounds like a plan.

I will let the car sit overnight and check pin #47 in the morning.

As far as wiring goes, it is likly my issue. My engine harness has been hacked up many times.

I will report back tomorrow with the results of pin #47.

good luck

My distributor should be fine. It has never had any oil in it any of the times I have taken it apart and the cap and rotor are in good shape.

Simply disable the set launch feature and it will always revert back to your launch RPM that you have set in the TCD.

If you can send or post a log of when this happens and your TCD, it will be much much easier to diagnose!

Does your neutral switch work properly?