Help please,
1992 plain-jane Q with 152,000miles, transmission shifts late, and when it does, it wants to downshift very quickly. It will shift to 4th around 70-75mph with light throttle. It feels like the convertor unlocks at 60mph. Also the idle speed stays around 1500rpm or more with the engine at normal operating temp. This happens without any pattern. This has been going on for about 3 months. I had the transmission serviced(fluid, etc...), NO change!:help
Razi
Tps
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maxnix
- Posts: 22627
- Joined: Mon Jul 22, 2002 8:11 pm
- Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45
Welcome, Razi. How about other maintenance? A 1500 rpm idle is not a good thing. Might respond with a more detailed maintenance history of your car in your next post.
Also, reading the previous posts will help you understand the issues with maintaining the VH45DE, as well as the transmission. I am sure the experts will want to know the conditon of the intake path and the EGR and IAC valves.
Three months is a long time to tolerate this kind of misbehavior from a Q45.
Also, reading the previous posts will help you understand the issues with maintaining the VH45DE, as well as the transmission. I am sure the experts will want to know the conditon of the intake path and the EGR and IAC valves.
Three months is a long time to tolerate this kind of misbehavior from a Q45.
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
3 hours is a long time to tolerate this kind of behavior but ....work demands are high for some.
That's the job of the convertor lock unlock system: to lock when you are steady rpm cruise and to unlock the moment you accelerate by even a small amount [say trying to go 5 mph faster or any time the accelerator is increased by say 10-20%], then to wait a tiny time and relock after it is sure you are not going to accelerate again.
That's the job of the convertor lock unlock system: to lock when you are steady rpm cruise and to unlock the moment you accelerate by even a small amount [say trying to go 5 mph faster or any time the accelerator is increased by say 10-20%], then to wait a tiny time and relock after it is sure you are not going to accelerate again.
Thanks for your replies
No big (drive you nuts type) problems with the car, so far
Injectors & sparkplugs replaced - ~6 months
Radiator+thermostat replaced ~1.5 years
Transflush - regular fluids(no fancy oils you guys use) ~1 year
Car driven - 5-6 thousand a year now for the last 2 years.
Fuel pump, filter, controller replaced 1.5 years.
Timing chains+guides replaced ~4-5 years
I think it may be the 'throttle position sensor', I found the service manual and ran the 'AT CHECK', came back with a '3' as the code.I want to know if you guys concur or have other ideas........
Thanks againRazi
No big (drive you nuts type) problems with the car, so far
Injectors & sparkplugs replaced - ~6 months
Radiator+thermostat replaced ~1.5 years
Transflush - regular fluids(no fancy oils you guys use) ~1 year
Car driven - 5-6 thousand a year now for the last 2 years.
Fuel pump, filter, controller replaced 1.5 years.
Timing chains+guides replaced ~4-5 years
I think it may be the 'throttle position sensor', I found the service manual and ran the 'AT CHECK', came back with a '3' as the code.I want to know if you guys concur or have other ideas........
Thanks againRazi
demhaizar wrote:This is an FYI post.
It has been about 2-3 months since I posted this problem.
I finally ordered a TPS, replaced it in 15min, started and went for a test drive and the car is as smooth shifting as it was when new. I had forgotten how much of a luxury car the Q is. Hope this helps.
Razi:ylsuper
THANKS for the follow up, it's this kind of "complete" probelms solving that helps make this board SO useful.
Happy Motoring
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Q451990
- Moderator
- Posts: 11030
- Joined: Tue Jul 23, 2002 8:21 am
- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
- Location: Columbia, SC
- Contact:
Interesting... we don't see may TPS failures. I guess anything is fair game after 11 years and 156K though. How did you get the TPS set right?
I believe it needs to be tweaked with Consult to make sure it's sending out the right voltage (or resistance) to the ECU. This is the ECUs way of knowing where the throttle is - so having the adjustment off can mess with your shift points. It may also be possible to set it using an ohm meter and seeing the resistance at closed throttle and WOT with the car turned off. Just make sure you do it after the car is warmed up so that the fast idle cam doesn't throw off the baseline.
Looking over the maintenence you've done - it sounds like you have had some good advice in the past... you mentioned you had your guides relplaced 4-5 years ago. Who told you about the problem? We've found that a lot of dealerships either aren't aware or aren't concerned about the issue.
Heath
I believe it needs to be tweaked with Consult to make sure it's sending out the right voltage (or resistance) to the ECU. This is the ECUs way of knowing where the throttle is - so having the adjustment off can mess with your shift points. It may also be possible to set it using an ohm meter and seeing the resistance at closed throttle and WOT with the car turned off. Just make sure you do it after the car is warmed up so that the fast idle cam doesn't throw off the baseline.
Looking over the maintenence you've done - it sounds like you have had some good advice in the past... you mentioned you had your guides relplaced 4-5 years ago. Who told you about the problem? We've found that a lot of dealerships either aren't aware or aren't concerned about the issue.
Heath
I am sorry for being so late, blame my tardiness on work , work and some more of the same.
Anyway, I did check the old unit before replacing and it was not to specs, I don't recall the exact #s.
Surprisingly the unit did not have to be adjusted, even though I was convinced to the contrary. The unit I recieved must apparently have been at the correct angle. I reseached further and found out that if you dare to buy a TPS from a used parts dealer then more than likely if the unit is removed carefully and the NOTCH (where the bar from the throttle cable side fits into it) is not rotated then it will not need to be adjusted, presumeably because it was already in the correct position on the original engine.
Have I confused you yet?! NO?, GOOD!
Razi:D
Anyway, I did check the old unit before replacing and it was not to specs, I don't recall the exact #s.
Surprisingly the unit did not have to be adjusted, even though I was convinced to the contrary. The unit I recieved must apparently have been at the correct angle. I reseached further and found out that if you dare to buy a TPS from a used parts dealer then more than likely if the unit is removed carefully and the NOTCH (where the bar from the throttle cable side fits into it) is not rotated then it will not need to be adjusted, presumeably because it was already in the correct position on the original engine.
Have I confused you yet?! NO?, GOOD!
Razi:D
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The whole trick is to get greater than 0.4 but less than 0.5 volts at 15 minute warm idle AND when the throttle is WOT at least 4.0 volts. I try for 4.44 volts.
The ecu/tcu divide the TPS voltage into 10 increments: idle, 1/10, 2/10..........9/10, and WOT..............there are in effect 10 load tables [actually just multiple equations] where things are different.
If cruise is 2/10 yet you force read 3/10 [from TPS] the ecu will have a hard time with precision fuel trim........thinking you must be going up a slight hill.
At a certain rpm, certain coolant temp, and a certain TPS, there should be a certain MAF voltage..........within + or - 10% [to allow for temperature and altitude differences.......... get any of these out of range and who knows what the ecu decides to do to make the engine run.
The tcu is dumber than ecu all it has to look at is rpm [input and TC slipped output], ATF temperature, car speed, and TPS voltage......to decide what to do.
The ecu/tcu divide the TPS voltage into 10 increments: idle, 1/10, 2/10..........9/10, and WOT..............there are in effect 10 load tables [actually just multiple equations] where things are different.
If cruise is 2/10 yet you force read 3/10 [from TPS] the ecu will have a hard time with precision fuel trim........thinking you must be going up a slight hill.
At a certain rpm, certain coolant temp, and a certain TPS, there should be a certain MAF voltage..........within + or - 10% [to allow for temperature and altitude differences.......... get any of these out of range and who knows what the ecu decides to do to make the engine run.
The tcu is dumber than ecu all it has to look at is rpm [input and TC slipped output], ATF temperature, car speed, and TPS voltage......to decide what to do.
Q45tech wrote:The whole trick is to get greater than 0.4 but less than 0.5 volts at 15 minute warm idle AND when the throttle is WOT at least 4.0 volts. I try for 4.44 volts.
The ecu/tcu divide the TPS voltage into 10 increments: idle, 1/10, 2/10..........9/10, and WOT..............there are in effect 10 load tables [actually just multiple equations] where things are different.
If cruise is 2/10 yet you force read 3/10 [from TPS] the ecu will have a hard time with precision fuel trim........thinking you must be going up a slight hill.
At a certain rpm, certain coolant temp, and a certain TPS, there should be a certain MAF voltage..........within + or - 10% [to allow for temperature and altitude differences.......... get any of these out of range and who knows what the ecu decides to do to make the engine run.
The tcu is dumber than ecu all it has to look at is rpm [input and TC slipped output], ATF temperature, car speed, and TPS voltage......to decide what to do.
Do you know if this is the same for sr. I had these questions on the forum about 2 weeks ago with little reply.
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Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
They are approximately the same as I remember all Nissan TPS are pretty much the same. Some may have closed and/or WOT switches which back up the reading double fail safe.
Resistance is a poor substitute for reading what the ecu receives via a Consult..........wouldn't think it would be accurate enough since Consult has a special proceedure to set TPS.
0.40--------0.45000000000000000000000000--------0.4999999 at idle.
4.0---------4.2000000 -----4.3------------------4.499999999 at WOT.
Really depends on TPS sensor temperature as the 5.00000000 volt reference supplied by ecu is very accurate.
Resistance is a poor substitute for reading what the ecu receives via a Consult..........wouldn't think it would be accurate enough since Consult has a special proceedure to set TPS.
0.40--------0.45000000000000000000000000--------0.4999999 at idle.
4.0---------4.2000000 -----4.3------------------4.499999999 at WOT.
Really depends on TPS sensor temperature as the 5.00000000 volt reference supplied by ecu is very accurate.