Water temp guage problem
Discussion
Guys,
Was up at Bedford today and had a problem with power dropping after a couple of laps. The power drop was happening at the same time as the hot water guage bouncing from 100c suddenly up to over 120c (and then dropping back to 100c after a couple of minutes) and the ecu was backing off the power due to temp reading.
My suspicions lie with the water temp sensor playing up. Anyone had this before ???
Was up at Bedford today and had a problem with power dropping after a couple of laps. The power drop was happening at the same time as the hot water guage bouncing from 100c suddenly up to over 120c (and then dropping back to 100c after a couple of minutes) and the ecu was backing off the power due to temp reading.
My suspicions lie with the water temp sensor playing up. Anyone had this before ???
Edited by Siban01 on Monday 31st August 20:16
I would expect that the gauge just displays the resultant temperature and the ECU would not be affected by the reading. You could after all disconnect the gauge and the car would run. I do suspect however that you had reached the intercooler/interboiler state and your ECU was cutting back due to high temps. BTW your old car doesn't do it.
Edited by Stella Artois on Monday 31st August 20:59
Yes - had exactly the same problem at Bedford a couple of years ago and recently at Silverstone.
Never happens on the road unless you simulate track driving (sitting at close to legal speeds at 5000 rpm in 4th for about 10 miles on a dual carriageway can just do it).
I too think it's a heat soak issue in the engine bay - I have just gone down the route of a front mounted oil cooler and had greatly improved performance at Silverstone in a repeat track session. Oil temp never went above 100C and no power drop off.
Never happens on the road unless you simulate track driving (sitting at close to legal speeds at 5000 rpm in 4th for about 10 miles on a dual carriageway can just do it).
I too think it's a heat soak issue in the engine bay - I have just gone down the route of a front mounted oil cooler and had greatly improved performance at Silverstone in a repeat track session. Oil temp never went above 100C and no power drop off.
Andrew.....did you get the same with the water temp guage flicking from normal temp (circa 100c) and then going off the scale? My drop in power was happening as soon as the water guage went off the scale and it wasn't a gradual increase.
I would expect a heat soack issue to be a more gradual increase?
I dont have an oil temp guage in my car so dont know what the oil temp was up to.
I would expect a heat soack issue to be a more gradual increase?
I dont have an oil temp guage in my car so dont know what the oil temp was up to.
Siban01 said:
Andrew.....did you get the same with the water temp guage flicking from normal temp (circa 100c) and then going off the scale? My drop in power was happening as soon as the water guage went off the scale and it wasn't a gradual increase.
I would expect a heat soack issue to be a more gradual increase?
I dont have an oil temp guage in my car so dont know what the oil temp was up to.
SimonI would expect a heat soack issue to be a more gradual increase?
I dont have an oil temp guage in my car so dont know what the oil temp was up to.
Yes - my temp gauge problem was exactly as you describe but jumping from around 95C to off the scale.
I don't know what the mechanism is that causes it - there is a view on this forum that it's the ECU giving a warning that the temp is too high before cutting engine power, however the TVR centre (ex Noble main dealers) tell me that the gauge feed is direct from the water temp sender.
My logic for fitting the oil cooler is that whatever the cause of the "flick" to the temp guage is, the root cause of power drop off is a build up of heat in the engine bay, as I only get the problem when track driving in hot weather - I watch the gauge creep up to beyond the normal road driving temperature then after a few minutes at 95C the "flick" happens. After a couple of these flicks, the power starts dropping off to the point where I might as well be driving my 530 diesel. The actual mechanism for the power drop off is probably intake temps getting too high and the ECU cutting back on power/boost etc.
Hence my solution of removing the heat from the engine bay with a front mounted oil cooler.
Works for me anyway!
Andrew
rsnoble said:
I have bin over mine time and time again, it would be good if you could tell me the location of the sensors?
Hmm - got the guys at the TVR centre to show me where it is on the 3R when I was down there having the work done.Looking at the engine from the passenger side of the engine bay you should be able to see a horizontally mounted short length of tubing (looks like about 6" of black plastic and shaped like the bottom part of a U with the two arms trimmed down) connecting the two banks of cylinders - almost exactly in the centre of the engine bay. At the right hand end (the rear of the car end of the tubing) you will see the water temp sender next to what looks like a blanking plate. This is almost immediately above the line where the bellhousing joins the engine block. Don't know if this will be the same location for your 2.5 though.
Best description I can give you and this is only going from what I can recall of what the guys at TVR centre told me and having just had a quick look on the car. Hope it's correct!
Good luck.
Edited by Air Support on Sunday 6th September 21:01
IIRC on 3R's and 400's the temp gauge is driven by the ecu, there is of course a temp sensor in the cooling system but this is connected directly to the ecu when your engine temps start to climb close to the point of detonation the ecu takes care of ignition etc and also sends a "high" voltage signal to the gauge, this is why the gauge appears to "jump" around at the point of cooling breakdown.
Normally if a gauge is connected directly to the cooling system it would just rise and fall smoothly inline with the actual temp of the engine.
F.C.
Normally if a gauge is connected directly to the cooling system it would just rise and fall smoothly inline with the actual temp of the engine.
F.C.
F.C. said:
IIRC on 3R's and 400's the temp gauge is driven by the ecu, there is of course a temp sensor in the cooling system but this is connected directly to the ecu when your engine temps start to climb close to the point of detonation the ecu takes care of ignition etc and also sends a "high" voltage signal to the gauge, this is why the gauge appears to "jump" around at the point of cooling breakdown.
Normally if a gauge is connected directly to the cooling system it would just rise and fall smoothly inline with the actual temp of the engine.
F.C.
So that would tally with exactly what I experienced on my last track day. My 2.5 that Marc now has didn't behave this way on track. Normally if a gauge is connected directly to the cooling system it would just rise and fall smoothly inline with the actual temp of the engine.
F.C.
Not being particularly mechanically minded, I'm a bit surprised that other ambient temperatures in the engine bay can have such an impact on water temp given that the water temp is cooled via the radiators? Is the water temp system for the Intercoolers separate from the engine cooling system?
I need to get this sorted as it seriously puts a mocker on the track day....I ended up buggering off at 3pm on a clear sunny day as I was so p**sed off with the whole thing.
So if it is purely heat soak issue then it sounds like the following routes would all help here :
- Heat wrap exhaust/manifold down pipes etc
- Oil Cooler
- Revised intercooler (e.g. PACE)
- Buy my old 2.5 back
Any other routes ??? My winter project list is rapidly expanding !
Siban01 said:
F.C. said:
IIRC on 3R's and 400's the temp gauge is driven by the ecu, there is of course a temp sensor in the cooling system but this is connected directly to the ecu when your engine temps start to climb close to the point of detonation the ecu takes care of ignition etc and also sends a "high" voltage signal to the gauge, this is why the gauge appears to "jump" around at the point of cooling breakdown.
Normally if a gauge is connected directly to the cooling system it would just rise and fall smoothly inline with the actual temp of the engine.
F.C.
So that would tally with exactly what I experienced on my last track day. My 2.5 that Marc now has didn't behave this way on track. Normally if a gauge is connected directly to the cooling system it would just rise and fall smoothly inline with the actual temp of the engine.
F.C.
Not being particularly mechanically minded, I'm a bit surprised that other ambient temperatures in the engine bay can have such an impact on water temp given that the water temp is cooled via the radiators? Is the water temp system for the Intercoolers separate from the engine cooling system?
I need to get this sorted as it seriously puts a mocker on the track day....I ended up buggering off at 3pm on a clear sunny day as I was so p**sed off with the whole thing.
So if it is purely heat soak issue then it sounds like the following routes would all help here :
- Heat wrap exhaust/manifold down pipes etc
- Oil Cooler
- Revised intercooler (e.g. PACE)
- Buy my old 2.5 back
Any other routes ??? My winter project list is rapidly expanding !
Heatsoak at the inter cooler will cause the ignition to back off due to excessive intake charge temp and resultant detonation.
This I imagine is only partially the problem with your car.
Things to check.
1 are you rad fans blowing in the right direction (yes i know but has been known)?
2 do you still have the cowling in place around the radiator?
3 Is the cowling sealed Sufficiently (with sticky back foam) to channel cooling air effectively?
If the above checks out ok I would look into a better high capacity radiator and oil cooler before trying to get power to remain constant.
once you have the engine cooling sorted then look improving the intercooler etc,
F.C.
F.C. said:
IIRC on 3R's and 400's the temp gauge is driven by the ecu, there is of course a temp sensor in the cooling system but this is connected directly to the ecu when your engine temps start to climb close to the point of detonation the ecu takes care of ignition etc and also sends a "high" voltage signal to the gauge, this is why the gauge appears to "jump" around at the point of cooling breakdown.
Normally if a gauge is connected directly to the cooling system it would just rise and fall smoothly inline with the actual temp of the engine.
F.C.
Agree on the ECU-driven gauge--it functions as an early-warning system to the driver when the cooling system is not doing its job for whatever reason. However, connecting a gauge directly to the cooling system does not guarantee that it will not act erratically. You will see sudden jumps in that case, too, if the coolant level gets so low that the gauge sensor becomes uncovered. That is, those sensors function best when they are completely covered by liquid, and they will not provide accurate readouts if exposed to a water/vapor mixture (steam).Normally if a gauge is connected directly to the cooling system it would just rise and fall smoothly inline with the actual temp of the engine.
F.C.
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