Thread: Rough, Unstable and sometimes high idle!

Thanks John.

I know I'm running big slow injectors and a few other odd bits a long way from a stock b13, and it's great that Nismotronic has such a large amount of variables to sort issues, the problem always seems to come when I'm trying to work out what to use to fix the issue. Reading the help file just doesn't help, so it comes down to trying to find a table that traces and changing things to see what happens, or choosing a value that doesn't trace and trying pot luck.

I just have to bump this thread:

My car was behaving exactly like Evlnxr's, revving between 1500-2000-1500-2000etc. at traffic lights. Also had a high warm idle (1500), that couldn't be solved by turning the screw on the IACV. This all started after my turbo install.

The problem? Waxstat mechanism on throttlebody. I had taken the coolant lines off this, and ran them to the turbo instead. This in turn made the waxstat on all the time, cracking open the throttleplate just so slightly. I noticed it on the datalogs, TPS @ 1% when warm.

Solution: Remove the waxstat. Two philiphead screws, remove the spring and plate. 900rpm warm idle. No more jumping at traffic lights!

If you have a bad idle, check your waxstat!

I gave up on a the AAC valve again and am just running Ignition idle control atm, and the bleed screw opened to get base idle around 1200 rpm.

My car is plagued with poor idle, ive tried all sorts, every single table in the software that has anything to do with idle control. It will sometimes start with a turn of the key and settle to a perfect idle, around 1000rpm, and will be perfect with a blip of throttle, then you back up a bit and stop and suddenly its dropping to almost a stall, then rev to 2k, and it wont stop until you drive off or give it some gas and let the revs drop slowly.

Generally speaking, my car is a pig to drive at slow speeds, which makes it not a lot of fun as a daily.

Hey Evlnxr are you running map or maf? I know I had the same issue and it was resolved going to a map setup. Reach out to John to see if you could potentially replicate setup.

Im running Map.

I havent really had a chance to play with things lately, my nemu died and i am using a borrowed one until i can work out how to fix it (i think its the onboard battery at fault), since then the tune is miles off, and ive had to change a lot of variables to get the car to run again.

Im getting quite close to ripping the whole loom and ecu setup out and starting over, since there should be no reason for Nismotronic to cause the crappy idle and poor economy as the software is so good and has so many items that can be changed for tuning. Or i could be missing something that i cant understand in the help file. I dont really know, the car has barely been used and ive lost a lot of interest in it.

@Evlnxr There are alot of variable that have to be checked when dealing with these isle issues on the nemu. It took me a very long time to correct mine, but you have to be patient. Is there any way you can posy a log of when you are driving so we can see what's going on?

Yeah, maybe if the weather clears up at some stage will plug laptop in and do some more logs.

This was a minor fluctuation from a couple of weeks ago, last week when i drove it the problem was way worse. There does seem to be a voltage issue as well, which i suspect has some relation to the afr going up and down, but its hard to tell what the cause is and what is a symptom of a cause.

The AAC valve always overshoots, so unplugging it still has some minor fluctuations, but at least the AAC isnt going from full open to full closed in a nasty cycle all the time.

You can cap the min/max values of the AAC valve so it doesn't fluctuate as much.

I will try to take a look at your logs and see if I can find anything!

Was going to take my car for a drive tonight, but ended up doing some work on it and then had to wait for thread seal to set.

Since unplugging the AAC and opening the bleed, the car has had very stable idle, barely ever dips and never overshoots. Ok, its idling at about 1100rpm, but its so stable, giving it a blip on gas pedal and it just drops right back to idle every time.