Nanocom erratic coolant temps and altitude turbo pressure

So I recently got a nanocom e2 and have been graphing data with it. The data logging feature of it is great, it has really helped me to understand how my Td5 has been running.

A couple of questions though for some more experienced nanocomers:

-Once my engine is warm, my coolant temp regularly jumps 2-5 or more degrees and a graph of it has spikes all over. I would have expected something a little more smooth. I've cleaned it off and the spikes were reduced, also don't seem to have any air in the system. I'm wondering if this looks normal or that I've got a bad sensor. I've attached a portion of my graph. Anyone else care to upload there's to compare?

-I live at 1320 meters, which according to basic pressure charts would be 87kpa, and that's about what my ambient pressure sensor is showing. However, the max turbo pressure I've seen (second gear, 3000+ rpm, floored, going up hill) is 148.

I found borntobemild's post at http://www.landyzone.co.uk/lz/f8/nanocom-reading-104682.html and figured out my theoretical max pressure to be 87kpa + 117.2 = 204kpa. Then it would be down about 14 percent (101 kpa at sea level versus 87kpa here) which would finally give me a max of about 175kpa.

My MAF isn't connected right now as I'm waiting on a new one, but would that influence turbo pressure? And can I rightly assume that 175 is a number I can try to adjust the waste gate to try to get to? (Once I get the new MAF)

Thanks in advance for your wisdom....

I dont have nanocom but i can tell that the coolant temp must not oscilate so... check the connection at the sensor's plug first and if it's ok put a new sensor cos it's not expensive

The MAF will not affect the MAP reading but the MAF controlls the EGR so it could restrict the pressure... if you still have EGR check it to not be clogged with muck, if not make sure the MAP sensor is clean enough...afaik normal readings are between the ambient pressure at idle and 230 kpa under heavy load

make sure there's no oil in the ECU red plug cos the MAP, coolant temp. and MAF sensor's inputs are there too and the oil could produce contact issues to them too

Good idea to check the connection on the sensor, although I think it's okay its worth a check and clean. I'm guessing that the previous owner who only used water for coolant for seemingly a long time (a lot of rust in the system) did the sensor in (along with the water pump, heater matrix and fuel cooler). EGR has been removed, and I've cleaned the MAP and there's no oil in the ECU connections. It'll be interesting if anyone else shows their temp readings just to see how they differ.

i've read mine several times with hawkeye and it stays without any fluctuations always where it just is(hawkeye can't save the data to show you)

Huh, interesting about the Hawkeye. I checked the connections and they look good. I'm going to go ahead and replace it, perhaps I'll post the graph after if there's any appreciable difference. May be of use someone perhaps.

If its as erratic as you say then it must be electrical as the actual water temp would not change that quickly because of the thermal mass. The gauge is driven by the ECU and not directly from the temp sensor. Does the temp gauge reflect the erratic readings or is it just something you have picked up on via the Nanocom?

Yeah, my thought too -- it simply wouldn't vary that much, and it starts to get more spiky once the engine is at temperature, so I'm thinking the sensor just malfunctions more when its hot versus cold. Once warm, the temp gauge is pegged at about 11 o'clock or so (just a little to the left of center) and doesn't move. And yes, I only noticed this graphing it w/ the Nanocom logging function.

BTW, the Nanocom's preset temperature alarm is 96 C, which struck me as being a little low and I've hit that a few times after going up steep hills here and having to stop. Was thinking 105 or so may make sense?

Off to order the temp sensor and maybe a thermostat too.

Dunno if anyone is interested, but here's a before and after Nanocom graph showing my old temp sender and after with a new one installed. Old one is full of temp fluctuations, new one is quite a bit smoother (but still not totally flat). Engine runs quite a bit more smoother now. Both graphs are the same range, and each line represents 2 degrees Celsius.

What's the reason for checking the AAP sensor and coolant sensor?..

Are you having power issues?

If the coolant sensor is duff, it either reads too high all the time, too low all the time, or your temp gauge will read zero and the high temp light will be on. The later happened to me. Don't be tempted to buy a £4 sensor, get a genuine one £16. Also wrap some heat shield around the wiring/plug to reflect heat from the head.

The AAP can have a big effect on low down power, especially if you are driving an auto. Boost will be down and the autobox will slip more/hang on to gears. Unplugging the AAP will resolve power issues if its reading wrong, however boost will be limited to 1 bar. I have an auto and unplugging the AAP proved it was reading wrong. Gear change now fantastic and its rapid, even though I'm only getting 1 bar of boost. AAP's are often knackered, but seldom get changed as they are £180 from L/Rover. I do believe you can get them cheaper, as they are used on other Rover vehicles and are half the price.