What is the coolant temp supposed to be when the car warms up in P and idling? I checke dmine and it is 173deg F with an ambient of 70deg F
Just doing some checking
J30 idle coolant temp
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Q45tech
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The thermostat just begins to open at 170F [100% open at 194F] so the design stablized temperature is somewhere around 170-194.........176F minimum for Consult to engage diagnostic tests.
After about 3-4 years the Nissan thermostats begin to dissolve the rubber surround [seal on flapper].....the idle temp gets lower and lower as a bit of coolant slips thru the seal.
After about 3-4 years the Nissan thermostats begin to dissolve the rubber surround [seal on flapper].....the idle temp gets lower and lower as a bit of coolant slips thru the seal.
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Mayhem_J30
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
You really can't trust the inside temp gauge other than cold [bottom], middle [somewhere near normal], higher than 3 o'clock [hotter than normal]!
This gauge is fed from a separate single wire sensor and is heavily damped to slow the response.....it will always lag by 4-7 minutes in showing warmer than normal temperatures.
The REAL engine coolant temp sensor is a very accurate 2 wire unit which feed the ecu.......its accuracy is 2-3-4F from 160-230F.
Critical milestones are 160F [when the ecu is allowed to enter closed loop fuel control program], 176F ideal operating temperature, 195F when ecu starts to remove timing sensing the beginning of an overheat [or just summer]. A signal is sent to ecu telling that AC is on so that may be the cause of 195F.
Each 5F increment above 195F decreases base timing by 1 degree to a maximum of 5 degrees at 216F.
For maximum power you NEVER want the coolant temp above 194.999F indicated and feed to ecu.
THE above is the NUMBER ONE cause of the noticed lack of power in Summer.
A brand new coolant system will work well but each year its capacity declines a little by 6 years or 70,000 miles it is doubtful that any meet new specs! Trash build up in front and in radiator fins, internal changes.
The only sure way to know is use a Consult and measure the ecu temp reading and plot a minute by minute graph, do a hot cruise test AC on and log the temp for 15 minutes [graph it manually].......watch what happens as you come off expressway and idle at a light for 2-3 minutes. Then do in traffic city street tests you will faint at how hot coolant gets .....220-230F.
A proper repaired and replaced coolant system will run 20-30F cooler in city heat.
It took me 3 years after 60k to figure this out then I had a special radiater built..........4.5 years [85k] later even this monster is starting to loose efficiency but it is still better than a new oem.
I have used NEW oem vs Griffin NASCAR in same week in serious day long back to back logging external temperatures TESTING and the better rad runs 7-10F cooler in similar and equal conditions.
It would be nice to have a 195F warning light to show you WHEN you are in the POWER DECLINE MODE...........for many that would be from April to October with an old cooling system.
SEE: the propensity for engine knock increases as the head temperature rises so the timing is retarded to hopefully compensate for this rise in coolant temperature!
This gauge is fed from a separate single wire sensor and is heavily damped to slow the response.....it will always lag by 4-7 minutes in showing warmer than normal temperatures.
The REAL engine coolant temp sensor is a very accurate 2 wire unit which feed the ecu.......its accuracy is 2-3-4F from 160-230F.
Critical milestones are 160F [when the ecu is allowed to enter closed loop fuel control program], 176F ideal operating temperature, 195F when ecu starts to remove timing sensing the beginning of an overheat [or just summer]. A signal is sent to ecu telling that AC is on so that may be the cause of 195F.
Each 5F increment above 195F decreases base timing by 1 degree to a maximum of 5 degrees at 216F.
For maximum power you NEVER want the coolant temp above 194.999F indicated and feed to ecu.
THE above is the NUMBER ONE cause of the noticed lack of power in Summer.
A brand new coolant system will work well but each year its capacity declines a little by 6 years or 70,000 miles it is doubtful that any meet new specs! Trash build up in front and in radiator fins, internal changes.
The only sure way to know is use a Consult and measure the ecu temp reading and plot a minute by minute graph, do a hot cruise test AC on and log the temp for 15 minutes [graph it manually].......watch what happens as you come off expressway and idle at a light for 2-3 minutes. Then do in traffic city street tests you will faint at how hot coolant gets .....220-230F.
A proper repaired and replaced coolant system will run 20-30F cooler in city heat.
It took me 3 years after 60k to figure this out then I had a special radiater built..........4.5 years [85k] later even this monster is starting to loose efficiency but it is still better than a new oem.
I have used NEW oem vs Griffin NASCAR in same week in serious day long back to back logging external temperatures TESTING and the better rad runs 7-10F cooler in similar and equal conditions.
It would be nice to have a 195F warning light to show you WHEN you are in the POWER DECLINE MODE...........for many that would be from April to October with an old cooling system.
SEE: the propensity for engine knock increases as the head temperature rises so the timing is retarded to hopefully compensate for this rise in coolant temperature!
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Redline wetter water raises the transfer efficiency [allows more heat to flow from hot head to coolant] thus the ecu temp sender may see a 2-3-4F warmer coolant [because it is mounted on the combined ouypuy of both heads] but the rad efficiency gets better as the differential [coolant vs air temp]temp increases so the inlet coolant [to the heads]temperature may decline percentagewise. Yet the outlet is hotter........better cooling efficiency!
It is a constant trade off between the knock sensors hearing knock and dropping timing 5>10 degrees and the ecu temp sensor responding to the very slight increase and removing an extra 1.0 degrees...because the coolant is a little hotter this can be addressed...............but 1.0 degrees is really not meaningful compared to not using the Redline product.
Those of you concerned with quarter mile times would do well to consider that you don't want the coolant to rise above 194.9F in the 15.0 seconds of wideopen throttle........pretty difficult when it might be at this when you start the run.
My guess is 0.1-0.2 seconds for very 5F [above 194F] your end of the run coolant is!
Pretty easy to see why some cars vary so much in warm weather.
It is a constant trade off between the knock sensors hearing knock and dropping timing 5>10 degrees and the ecu temp sensor responding to the very slight increase and removing an extra 1.0 degrees...because the coolant is a little hotter this can be addressed...............but 1.0 degrees is really not meaningful compared to not using the Redline product.
Those of you concerned with quarter mile times would do well to consider that you don't want the coolant to rise above 194.9F in the 15.0 seconds of wideopen throttle........pretty difficult when it might be at this when you start the run.
My guess is 0.1-0.2 seconds for very 5F [above 194F] your end of the run coolant is!
Pretty easy to see why some cars vary so much in warm weather.
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
By the way the auxillary electric cooling fan comes on [on early Q] when the radiator outlet side temperature is 194F [+-] so the ecu is seeing a 205-215F temp reading out of the heads. So the engine is already seeing a 3-5 degree ignition retard.
* generally the outlet vs inlet temp across radiator is 20-25F but this varies with ambient and air flow rates plus the water pump speed and thermostat restriction.
It [mechanical reed switch screwed in to drivers side of rad] is set this high to avoid wearing out the [expensive and hard to change] aux fan motor prior to 70,000 miles in warm climates!
The 92-93 and 94 had 2 speed auxillary fan motors which tended to run on low speed earlier [almost whenever the ac was on and it was 80F outside] to try to head off the extreme temp rises and need for the fan's high speed running.
Plus the fans running at the low speed helped with the loss of AC efficiency as you came to a stop ......providing another minute or two of time before the AC felt warmer [for stop lights]...........sitting still too long would engage the high speed position but this is not equal to the mechanical fan at say 30 mph.
Very intersesting to plot graph AC outlet temperature vs engine rpm/vs coolant temp vs time at idle........vs sunload vs number and weight of occupants.
Even a 5% error in Freon charge weight is quite dramatic and can be the diffence of 4-5F in outlet temperature when stablized.
The is an ecu controlled compressor clutch cut off under WOT but this has a lag of a second or so!
* generally the outlet vs inlet temp across radiator is 20-25F but this varies with ambient and air flow rates plus the water pump speed and thermostat restriction.
It [mechanical reed switch screwed in to drivers side of rad] is set this high to avoid wearing out the [expensive and hard to change] aux fan motor prior to 70,000 miles in warm climates!
The 92-93 and 94 had 2 speed auxillary fan motors which tended to run on low speed earlier [almost whenever the ac was on and it was 80F outside] to try to head off the extreme temp rises and need for the fan's high speed running.
Plus the fans running at the low speed helped with the loss of AC efficiency as you came to a stop ......providing another minute or two of time before the AC felt warmer [for stop lights]...........sitting still too long would engage the high speed position but this is not equal to the mechanical fan at say 30 mph.
Very intersesting to plot graph AC outlet temperature vs engine rpm/vs coolant temp vs time at idle........vs sunload vs number and weight of occupants.
Even a 5% error in Freon charge weight is quite dramatic and can be the diffence of 4-5F in outlet temperature when stablized.
The is an ecu controlled compressor clutch cut off under WOT but this has a lag of a second or so!
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maxnix
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1995 Infiniti Q45t
2000 Infiniti Q45
Great Information
Now if I could just remap my auto climate control.
Tried leaving it in Econo mode on trip to Portland from Seattle, but windows would fog when heater came on without AC (~50° F, 95% humidity). Gave up and did 1/3 of the trip on Auto. No real change in mileage, but couldn't always stay below 2500 rpm either.
Just can't imagine changing to shorter rear end and leaving closed loop at 65 mph. Had to vanquish a few left lane bandits on the way back; mostly SUVs, minivans, pick-ups, v6 sedans, a Cad or two, a couple of BMWs, well, you get the idea. The passing performance is absolutely effortless and seductive.
Tried leaving it in Econo mode on trip to Portland from Seattle, but windows would fog when heater came on without AC (~50° F, 95% humidity). Gave up and did 1/3 of the trip on Auto. No real change in mileage, but couldn't always stay below 2500 rpm either.
Just can't imagine changing to shorter rear end and leaving closed loop at 65 mph. Had to vanquish a few left lane bandits on the way back; mostly SUVs, minivans, pick-ups, v6 sedans, a Cad or two, a couple of BMWs, well, you get the idea. The passing performance is absolutely effortless and seductive.