Thread: Rough Idle & Fault Code

Here is a record of the fuel input for my drive to work yesterday evening. Hope we can find a reason for rough idle & code within the file.

I ain't no expert here, but firstly anyone know what the logging frequency is for the nanocom.
I either can't remember, or have never used it.

Anyhow, I can see a couple of anomalies in the fuel temp results.
You have at least a couple of spikes(that I immediately found)

Notice on the fuel temp column how there's a steady progression increase in temp.
As you scroll down, where the fuel temp is at the 61.7 point, there are 4 logged values of 61.7 proceeding the series of 67 values, then a jump to 81.8, then it settles back to the 67's .. like 67.5 or something.
This is no good.

It happens again as you scroll further down.
Now into the 71°C range, I think about 71.6, then there's another spike to about 86.3 for a single value, then back down to the 71's again for a while.
Immediately after that you then have some frantic readings. from 71.something down to 60, and up again.
Fuel temp shouldn't rise and fall so quickly(but again I don't know the logging frequency).
is it 5 sec, 1 min???

Then you'll see it again when the stable values are in the 72 range, and you see a whopping 124.3 spike again.
Keep scrolling and you see it seems to stablise at about the low to mid 70's, and not far below the 124 spike there are again some spike up to the 90s' and down to the 60's.

remember I'm no expert, but from the logging I check on my 1Gauge(on my D1) .. spikes indicate loose connectors(so far for me) .. and most likely sensor playing up or dying.

Like SF said ... possibly a fuel temp sensor replacement is in order.
Before you do that tho, could be a connection issue.
Fuel temp sensor on the whole seems to be stable, other than those spike anomalies .. so I'd take the connector off, give it a spray with ... <insert favoured> spray stuff .. brake cleaner/contact cleaner/WD40 ... and when refitting connector make sure it's a nice tight fit too.

** as a side note too. it seems you went for a bit of a test drive, judging by the road speed log. The note worthy of comment is that you also have a few(I think 3) spikes in road speed.
You could easily ignore those if the data captured was via GPS, but I don't know of any GPS feature of the nanocom, nor the D2. So assuming you have a speedo corrector or something fitted.
But it's amazing to see that the D2 was doing 113 k/h whilst standing still and the spike to 151k/h from 43 and then back down to 33, it looks like whilst coming to a slow point(engine revs at about 700 rpm).

Anyhow, I can't imagine what could cause those spikes in speedo for a fixed system .. unless you have a speedo corrector and the connections to and from it are a tad loose too.

Correct I am running 265 70 16 tyres which are about 7% bigger than standard. I have a Di Hunter Speedo correction box. Ive has zero issues with the speedo corrector. It always works without fail. I’ve calibrated the nanocom speed with my gps and checked that with the dash speedo. What I did find strange is that the dash speedo said I was doing about 98 (I take the expressway to work), but the fuel logging page said I was doing something like 88-92kmh. I would have thought that when I calibrated the speedo on the nanocom that it would have carried those settings through to the fuel logging page.

The other thing I noticed was how irrational the cylinder balance is. I’ve noticed since doing the injector seals a year or so ago that cylinder 3 has always had a higher balance than the other 4

Originally Posted by John_D2

Correct I am running 265 70 16 tyres which are about 7% bigger than standard. I have a Di Hunter Speedo correction box. Ive has zero issues with the speedo corrector. It always works without fail. I’ve calibrated the nanocom speed with my gps and checked that with the dash speedo. What I did find strange is that the dash speedo said I was doing about 98 (I take the expressway to work), but the fuel logging page said I was doing something like 88-92kmh. I would have thought that when I calibrated the speedo on the nanocom that it would have carried those settings through to the fuel logging page.

No, I'm pretty sure only the speedo and "mileage" are affected by the DiHunter unit.
Have you also adjusted your nanocom ratio so the speedo there in instrument mode reads correctly (real speed)?

Originally Posted by gavinwibrow

No, I'm pretty sure only the speedo and "mileage" are affected by the DiHunter unit.
Have you also adjusted your nanocom ratio so the speedo there in instrument mode reads correctly (real speed)?

Yes I have. That’s what I was trying to explain earlier

Originally Posted by John_D2

Correct I am running 265 70 16 tyres which are about 7% bigger than standard. I have a Di Hunter Speedo correction box. .....

OK.
But if I were you, I'd still check the connections.
Both the fuel temp sensor plug and the connections to the speedo corrector.

Can't imagine any other reason why the speedo would spike the way it shows in your logged data.
Assume you used spade connectors from and to the corrector?
Double check them.
Maybe the correction factor feature on the Nanocom is for the display(instrument mode) only?
Dunno.

With the fuel temp sensor, remove connector, spray drive again and log it. look for spikes again in the data log.
If you see more spikes in values .. suspect the sensor.

Originally Posted by AK83

OK.
Can't imagine any other reason why the speedo would spike the way it shows in your logged data.
Assume you used spade connectors from and to the corrector?

I’m normally more of a solder and heat shrink guy myself. I do use spades but I think I soldered most of the connections.

I’ll do your suggestions tho. How easy is it to replace the sensor?