Yes that is what I thought so I tested each of the sensors to see what happened with temperature. The gauge sensor is, as stated, a "straight forward" thermistor but the ECU sensor is designed to switch from high resistance to low resistance at ~ 40°C to ensure that the ECU switches from the "Cold Map" to the "Hot Map" at the earliest opportunity to save both on economy and the generation of HC. This device also has a high level of hysteresis built in to ensure that the system does not accidentally switch back to the "Cold Map" should the engine undergo some freak overcooling - I had to immerse the switch in cold water to get it to switch back after heating whilst the transition from high to low resistance takes place over about 5°C around 40°C. I was surprised at this response so I checked this three times and the above characteristics were repeated each time.
Whilst the car is not suffering from poor performance, I will check the inlet manifold temperature sensor as I had forgotten that! Thanks for the tip! This really is a matter of having everything working properly and giving readings that are believable. A low reading temperature gauge is more of a distraction than anything else as it is not calibrated in any scale but if it is not indication in the right region I start to wonder if anything is wrong. The worst thing in that respect is the speedo on Trish's Micra, which reads ~9.8% high. We complained to Nissan shortly after we bought it to receive the reply "If it is within 10% then it is legal and we are not going to change it!". Since the speedo is driven by the ECU and recalibration is simply a number change in the ECU via the device they use to reset the service interval, I was not impressed. After last year when they charged us 50% more for the last service done under the guarantee and only completed half of it as well as cross threading the sump plug (for which they tried to put the blame on me whilst they are the only people to have touched it) and not finding the air-con pipe that had worked its way loose, we will not be returning to that garage, even to keep the computer record up to date. Hamish -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of ChrisC Sent: 14 March 2012 13:49 To: Quantum Owners Group Subject: [Quantum Owners] Re: Low Reading Temperature Gauge On both the CVH and the Zetec engines, the gauge sender and the ECU sensor are totally separate; not sure what you mean by an ECU switch? they are both thermistors (resistors which decrease in value with applied temperature). Just a temperature gauge reading alone shouldn't affect economy. On mine, you can see/hear the idle speed drop in one jump as the engine warms up, which indicates that the coolant temperature sensor is working. I had an issue with poor low-revs acceleration on my CVH-engined H4 (a flat spot about 1800 rpm) - replacing the intake manifold air temperature sensor seems to have helped significantly, although there is still a little hesitation when the engine is warmed up. Chris -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/quantumowners?hl=en IMPORTANT NOTE: All information presented herewith is provided on an "As Is" basis, without warranty or the implication thereof. Neither the Quantum Owners Club nor the individuals associated with the Quantum Owners Club or in the preparation of the above information shall have any liability to any person or entity with respect to liability, loss, or damage caused or alleged to be caused directly or indirectly by the instructions contained within this or related message(s).
