Jump to content

Nissan 350z oscillating rpm, first startup.


Recommended Posts

Hi there,


I joined a couple of days ago and after seeing other people getting great help i decided to post my current challenge.

I switched ECU from Haltech to Link on a previous car of mine. Car ran fine with the exception of oscillating rpm's during idle. Never found the time to fix it . Now i have another car, also a Nissan 350z with a new build on it, and using the same Link ECU. I created a new map which currently is still bare but just enough to start up.  Right after startup i see the same oscillating coming back. Maybe you guy's know whats going on? I have the assumption that the idle base position table is not holding the right values.

Another question which just popped up: for this car i'm using a fuel pressure regulator which is connected to MAP. Can i use traditional fuel equation? im trying to figure out which works best for me. Coming from Haltech where i have to input the fuel pressure and tell the ECU its a MAP referenced fuel pressure. I hope you can advice me?


Kind regards!


attached the map and log file.

Log 2018-05-12 11;42;37 am.llg

350 coupe new 08-05-2018.pclr

Link to comment
Share on other sites

There are several things here that  are a bit off and will be making it misbehave, but I think your oscilating idle is a simple case of not having injector short pulse adders entered, and that fact that setting the fuel numbers to 25.4 everywhere doesnt actually give you a fixed injector pulse width at different RPM and MAP as a few other numbers are multiplied into the fuel number to determine the injector pulse.

If you want to use traditional fuel model, change this before you even start trying to tune it. If you want to leave it in modelled mode, set you injector data correctly and copy the fuel table from the monsoon base map as a starting point. Having a flat fuel table like this in modelled mode is never going to behave well as you arent actually telling it to always give the same amount of fuel, you're telling it that engine VE doesnt change with revs or MAP, which is not true

You should also run the calibrations for the accel pedal and throttle plate - tps main and sub are nearly 1% apart at most times, and AP is sitting at 3%. If you're holding the pedal open a bit this might be right, but it should read 0% with your foot taken off it.

Your idle control lockout is 3% AP, and with it seeing 3.2% AP all the time, idle control isnt doing anything here, the problem is elsewhere in the tune.


Link to comment
Share on other sites

Hi there!


Thanks for your reply! I will look into the pulse adders. Thanks for pointing those out! :)

The flat fuel table is just to get the engine to start and this was the ballpark figure. I will indeed need to add sensible data. I was afraid the oscillating i had in the other car came back so i asked for help.

for now i will stick to traditional. I was curious how the calculation of the right amount of fuel was calculated without entering the fuel pressure.

And indeed i was holding my foot on the AP just a litle bit. i will update the idle base table until the foot on the AP is not necessary.

Thanks a lot this far! Will try this later in the evening and will get back here with the outcome!


Kind regards!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...