Nistune Forums

Hey all.
This isn't a nistune problem, something to do with the car, but I'm running out of ideas.

Car is a VL turbo 5 speed. RB30ET with Nistune, GTR injectors, intercooler, 14psi from std turbo, 3" exhaust. Basic setup.

The car has developed a misfire, it starts at around 2500rpm, wether under load or just revving the engine. Once the misfire starts, the tacho starts jumping around erratically regardless of actual engine rpm, anywhere up to about 5000rpm. I have an led shift light set at 5500rpm and it flickers on and off, sometimes on constantly, and the car has no power obviously.

So in my mission to fix it the following have been replaced:
Crank angle sensor
rotor button
dizzy cap
leads
plugs
coil
power transistor

And i still have the same problem.

Any pointers as to where i should be looking next? I was leaning away from wiring issues as i figured that would lead to the problem being there at all times, not only over certain engine rpm. I will grab a log shortly and post it up.

Thanks
Scott.

Can't get a log, nistune and my a/d converter for my wideband both keep crashing, seems as soon the misfire happens? not sure how they would be related. Its raining here at the moment so only trying to log in the shed under no load. I'll get it out when the weather fines up a bit and get some logs under load.

Scott.

when it crashes does the whole PC freeze up or just the software itself? Combination of using DLP + Type 1?

as for the problem itself, not sure on the cause for this. tacho jumping around is a concern and would be indicative of CAS / wiring problem I would take a guess at

Just logging in Nistune RPM how does that look?

Sorry for the late reply, seem to have no time to work on the car these days...

The laptop freezes up. its like something is using up all my memory and it just slows to a complete stop.

Sorry , in my last post i said A/D converter, i mean usb/serial converter.

Have done a heap of logs, pain in the neck as the computer needs to be restarted every time it freezes, and the attached 2 logs are the only ones that captured anything. The rest froze as it happened. The time into the log that the blip in RPM occurs is in the file name. I also have trouble once the laptop is restarted connecting to my wideband for some reason.

Thanks guys.
Scott.

Have you tried disconnecting the tacho/shift light signal wire to illiminate a tacho signal load fault.

The MAF voltage looks very eratic. Is the wire broken dangling inside the centre?

We noticed this on the dyno last week with the DLP. It seems to chew up the processor time. I'm going to look into it further as it makes software unusable

Hey guys,
Still haven't had a chance to work on the car, but going to do a few jobs on her tomorrow.
Matt - No DLP here, i meant to say serial/usb converter not A/D converter.
Will disconnect the shift light and isolate that part of the equation.
Was thinking about it, the laptop freezing up/ disconnecting etc, has probably only been happening since i moved the battery to the boot. Could noise be an issue, or stray current or something?. The battery is mounted in the boot, the neg terminal goes to chassis ground, and i have put an extra earth from the block to the chassis. the pos terminal runs up to the pos terminal on the starter solenoid, and the battery harness modified to take its power from the pos starter terminal. Would i be better off running a cable from the neg terminal all the way up the front to the block or chassis possibly?

The other thing that seems to be happening, when driving, say you pull up for a red light, the engine doesn't come straight back to idle, it hovers around 1500rpm for a while, probably 10sec +, before slowly coming back to idle. Anything related you think?

Will post tomorrow after i try out a few things.

Scott.

Hi Scott,
Is the battery/Alternator ok?

The Battery has definetly lost around .8Volts getting to the ECU connector from looking at your logs.
The alternator is either not doing it's job to keep a good 14.1 or the voltage is lost in the cable.

As a reference: When things are good, the Battery output received at the ECU is usually around 13.8-14.0 volts plus/minus .3volts on all the VL's i've come across.
note: A 0.2volt loss is often noticed when comparing Nistune to the Batt Terminals.

If the battery is new and cable/connectors of a heavy enough gauge, I would check the condition of the Alternator's regulator/Brushes.

Thinking out loud: The battery is usually the only noise filter for the cars electronic components and you just moved it to the boot, makes me wonder if this would have an effect of increasing ignition noise to the ECU as you stated earlier, and if so where to put a suppresor or a small extra 12v battery to reduce it?

Look forward to your resolve

Hey guys.
Ok. Seems i have 2 separate problems. The issue with the misfire, tacho jumping around etc, is in the engine harness near the crank angle sensor. I have had the CAS plug on and off a hundred times over the last few months and it never made a difference, however one day while mucking around and bumping that part of the harness the rpm picked up a bit. i found that pushing on the plug/harness effected how it was running. pulled the plug off, checked pins etc, pulled the rubber boot back and noted some cracks in the insulation on the wires. after putting it back together i have not been able to make it play up again. been about a month now. I have a new plug ready to go on, just waiting for it to play up again, so i can work out wether its the plug or harness, and can fix it permanently. can't pick up any problems in the plug or harness when i check it with a meter. So problem 1 fixed. almost.

Problem 2, is related to the nistune/wideband disconnecting. This is still happening. Whenever i place the engine under full throttle/high load i seem to get the disconnects. Thinking this is an earth problem with either the wideband or the ecm, related to moving the battery to the boot. Would running some extra earths, possibly directly from the lc-1, and ecm straight to the battery possibly help? Or possibly needing to earth the laptop, i have read about doing this before too.

Scott.

Scott, Gota say I've earthed laptop, earthed the ECU, Earthed the Wideband, earthed the carpet, earthed the driver and earthed the earth.

I've used the same Nistune ECU on a few different VL's now and each one is different, some disconnected every 10 minutes, some every 30, some never, some after starting some don't after a start, some after revving high, some after returning the throttle.

In the last VL, the only thing that has made any difference is renewing the 0.47 cap (the white plug that goes into a black connector) in the harness near the engines RPM check point connector just down under the coil.
In the VL manual its sometimes refered to as the radio supressor.
It can reduce some of the electrical noise generated by the ignition system.

If all else fails, installing Nistune into another ECU usually fixes it. Done that too!!

Tried the ferrite core around the USB cable at all?

I've fixed some bugs with wideband disconnects (during sync) and crashes last night but if you are getting laptop freezing up then might need a debug log file (use the latest version when you do this)

Whats this ferrite core for the usb cable Matt? acts as a noise suppressor i take it?

I'll try a few of these ideas and see what happens.

Cheers.

yep seen here
viewtopic.php?f=3&t=1182&p=9765&hilit=ferrite#p9765

Couple of updates.

The disconnects are related to my wideband. Nistune seems to run fine while the wideband isn't connected, crashes as soon as i connect. This only happens since i moved the battery to the boot, so I'll check earths etc on the wideband. Also need to update to the latest version of nistune, so I'll do that first.

I seem to have a few electrical problems, after doing a bit of work on the car yesterday my misfire is back. Gave the harness a good shake all over only seemed to make things worse on occasion, however with it being so old and stiff its hard to isolate the problem to one area. I am going to take the harness off cut it open, give it a good check over. I'll replace all the sensor connectors while im at it. Anyone know if i have to buy the connectors from Holden/Nissan, or do the likes of Bosch or someone sell them? I have a couple of harness' from N/A engines here, if its easier I'll just add the knock sensor wiring to one of those.

Battery voltage. At the alternator, starter, battery etc i have about 14.2 volts. Nistune displays about 13.3. I'll pull the ecu out and test all the wiring and see where the voltage drop is coming from.

I'll do some more on it tomorrow.

Scott.

My red GTS is having similar issues with wideband... bad issues!

When I have the ECU and wideband running it actually affects the car! I dont have the ECU grounded at this time so thats the first thing I will do next time I test out. There must be a ground loop between the wideband and the ECU I'm thinking. Didnt have that with the other car but was running LC-1 not LM-2

The point is that the wideband uses a lot of current to run the heater. This drains the battery and needs good connections otherwise may cause other issues. Check you have thick cabling and secure connections