Hi, I have a 91Q45t that has 180,000 miles on it that is starting to stutter every now and then in what seems like 3rd gear. It only happens when I accelerate very gradually up to highway speeds. If you drive it aggressively from 40 to 55MPH it doesn't happen. When it happens, the engine rpms seem to drop from about 1700 down to 1400, and the car is usually going somewhere between 45-50 MPH. Ideas?
The only transmission related problem the car has had is that it got stuck in 3rd gear once. This was fixed under factory warranty about 120k ago. The dealer put the aux tranmission cooler in at that time. I think I had the transmission fluid flushed about 50-60k ago. The fluid is a light purple color now.
Other info: I've been driving this car for the past 11 years in MN. The engine seems to be in good condition (although I still need to get new guides installed). All the injectors are in good condition, the fuel pump has been replaced 30k ago, and the computer was replaced with one from a junkyard Q about 40k ago (after a friend did a big electrical no-no accidentally).
transmission or engine stutters on my 91 Q45t
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Q45tech
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- 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
"I think I had the transmission fluid flushed about 50-60k ago. The fluid is a light purple color now."
Not bright shiny sparkling red? We recommend a flush every 2 years or 30k which ever comes first. Pan drop and clean plus new internal filter........did they add the external filter when they did the tiny finned external cooler.
Shutter description sounds like worn lockup clutch or just worn out ATF [stick/slip additive depleted].
Not bright shiny sparkling red? We recommend a flush every 2 years or 30k which ever comes first. Pan drop and clean plus new internal filter........did they add the external filter when they did the tiny finned external cooler.
Shutter description sounds like worn lockup clutch or just worn out ATF [stick/slip additive depleted].
A lot of hi mile Q's have this EXACT problem.Many (if not most) drive for years with it and not ill effects otehr than the shudder.
My solution was, when in town leave the car in "3", problem solved.
When in town leaving in 3 is better anyway sincve you will lug the engine less and impose fewere shifts (and therefore less wear) on the transmission.
Fred..
My solution was, when in town leave the car in "3", problem solved.
When in town leaving in 3 is better anyway sincve you will lug the engine less and impose fewere shifts (and therefore less wear) on the transmission.
Fred..
Where would I look for the possible external filter? I didn't see anything that jumped out as a filter when I did a quick look for it.
In the mean time, I've been driving it like my grandma would to keep any possible wear and tear to a minimum. It's amazing how much better gas mileage you can get when you do this.
In the mean time, I've been driving it like my grandma would to keep any possible wear and tear to a minimum. It's amazing how much better gas mileage you can get when you do this.
He's not talking about external filter, but the factory one, that you replace in a pan drop.That itself <might> be 50% of your problem (Prob not, but it might)The rest can be dirt/wear/ or depleted additives.
Change the fluid as mentioned above.Did the dealer actually put in an external transmission cooler that bypasses the stock heat exchanger (which is the highly recommended set-up here)?
there is a small external extra fins kinda filtyer thats part of a OEM transmission update, check if you have this or the radiator bypassing external cooler set-up.
Fred...
Change the fluid as mentioned above.Did the dealer actually put in an external transmission cooler that bypasses the stock heat exchanger (which is the highly recommended set-up here)?
there is a small external extra fins kinda filtyer thats part of a OEM transmission update, check if you have this or the radiator bypassing external cooler set-up.
Fred...
I can't find the service papers from the dealer (Infiniti of Bloomington) detailing what work was done, but I did find some verbage in the cars service manual. It says that an auxillary cooler and filter were added in Febuary of 1993.
When I look at the bottom of the car, there is a 6 to 8" block of 1"x1" square fins in front of the pan. That sounds like it's the external cooler, right?
When I look at the bottom of the car, there is a 6 to 8" block of 1"x1" square fins in front of the pan. That sounds like it's the external cooler, right?
drewbert:What you see is the factory upgrade.
It is much more effective ( and kinda cheap) to install an aftermarket transmission cooler that bypasse the stock heat exchanger entirely.
Even in MN thats a good choice ( I lived in Minneapolis for some years.
Aside from the cooling issue, bypassing the factory heat exchanger is a good idea, since the factory lines to the heat exchanger tend to get clogged (I lost a transmission that way btw)
Fred...
It is much more effective ( and kinda cheap) to install an aftermarket transmission cooler that bypasse the stock heat exchanger entirely.
Even in MN thats a good choice ( I lived in Minneapolis for some years.
Aside from the cooling issue, bypassing the factory heat exchanger is a good idea, since the factory lines to the heat exchanger tend to get clogged (I lost a transmission that way btw)
Fred...
After following everyones advice and reading a couple more posts related to transmission flushes, I brought the car in today and got it flushed with Mobil 1. They did the pan drop after the flush at my request, and they said that the pan was very clean, but the fluid was fairly dirty.
I could tell what a difference it made while driving home. Some minor jerks that used to happen while the transmission shifted between gears are gone now, and the stutter is gone as well.
I was keeping an eye on the RPM's while driving, and they still drop from around 1700 down to about 1450. I verified that this is actully happening in overdrive, not 3rd gear. Is this normal? I can't remember it doing this before.
I could tell what a difference it made while driving home. Some minor jerks that used to happen while the transmission shifted between gears are gone now, and the stutter is gone as well.
I was keeping an eye on the RPM's while driving, and they still drop from around 1700 down to about 1450. I verified that this is actully happening in overdrive, not 3rd gear. Is this normal? I can't remember it doing this before.
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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 locking and unlocking of the torque convertor......drag on engine............remember the TC clutch is very weak and cannot take muck power ][acceleration] therefore it unlocks before it slips much and burn up.
1400-1550 rpm in 4th/////40-49 mph is TOO LOW an rpm to expect the engine to function properly...bucking and snorting and shuddering if everything is not perfect.......running the AC takes away 5 HP that maybe needed........what if the engine is worn or dirty and not producing the as designed power at 1400 rpms........of course it acts funny.
Brand new and even at 60k the engine just made enough......not much margin to move a 4300 pound car.
The worst ones are the engines with the K&N cone filters which destroy the tuning [the Stock sound silenceing convolution is tuned to boost the power in the every low rpm thru 55 mph range].
1400-1550 rpm in 4th/////40-49 mph is TOO LOW an rpm to expect the engine to function properly...bucking and snorting and shuddering if everything is not perfect.......running the AC takes away 5 HP that maybe needed........what if the engine is worn or dirty and not producing the as designed power at 1400 rpms........of course it acts funny.
Brand new and even at 60k the engine just made enough......not much margin to move a 4300 pound car.
The worst ones are the engines with the K&N cone filters which destroy the tuning [the Stock sound silenceing convolution is tuned to boost the power in the every low rpm thru 55 mph range].
I'll try to remember to hold on to 3rd gear a bit longer so when it shifts into 4th it will be well above the point where it could encounter this issue. For extended periods of following cars at these speeds it sounds like Fred's idea would work well... Drop it down into 3rd gear manually.
Thanks for all the help!
Thanks for all the help!
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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
Takes an hour above the normal $99-$129 BG machine Flush to remove, clean, change internal filter, and reinstall the pan readding the 3 quarts of ATF.
If you got 180k our of a 91 transmission you have done extremely well. Better than anyone I know especially with so little maintenance expense. Guess the MN cold is better than the GA hot.
If you got 180k our of a 91 transmission you have done extremely well. Better than anyone I know especially with so little maintenance expense. Guess the MN cold is better than the GA hot.
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nuQ
- Posts: 1659
- Joined: Thu Jan 23, 2003 1:39 pm
- Car: 2003 Infiniti M45
2009 Dodge Caliber SXT - Location: Bethlehem PA
mine 90Q does something very similiar. normally happens between 40 and 65mph, when i level out my speed a very slight shudder happens, not everytime, but alot. my rpm's, however, do not budge. i've had a complete transmission flush, pan and screen removal, and refilled w/ mobil 1 about 2 months ago. didn't really notice any big change, though. the transmission was rebuilt about 2 years ago. the tech who did the flush said the old fluid was pretty shot. hope this isn't a sign of things to come!!!! jeff
Well, I started an entire thread about this a month or so ago and I did not get any transmission comments at all, maybe because I mentioned that it was a 92 Q on it's second trans with all the updates done. The comments I got at that time were all about injectors, maf, knock and o2 sensors. Now I hear it may be the transmission? And the way it's being described at 40-45 mph sounds exactly the same as mine. It's going in again in a week to have this completely looked at. Some of you are saying it's just normal and live with it? Two threads, one ends up with an analysis of injection, and engine controls issues, this one suggests the transmission. What is the best guess for this shudder? Feels like a temporary miss while going through 40-45mph on gentle acceleration. One more time please. Especially as mine STARTED behaving like this a month or two after the last flush. I'm at 130k and almost everything has been upgraded including throttle body clean, injector clean but the plenum has not been removed, cleaned and the hoses underneath have not been changed out, or have the injectors. The disturbing part of this thread is that I was prepared at this point to tell them to pull the plenum, clean everything and replace EVERY hose they can find, and maybe do all the injectors. Now I'm not so sure. It might still be the transmission? Can any expert here help me determine which way to go here? Cause you know the dealer will be happy to go both ways at twice the cost!
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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
Lugging the G50 Q45
Read the how to drive threads. As Q45tech states, lugging the engine in OD at 40-45 mph is not conducive to long transmission life nor smooth engine operation.
I think this is something more symptomatic of 1990-1993 Q45s and their single pintle injectors and individual intake ports. The later 1994-1996 disc injectors and intake path modifications seem to eliminate this tendency. I say this because I can drive either of my under 60K 1995 Q45s like a grandma in D with no problem with light throttle at those speeds. But I don't..
Almost always in 3 until 60 to 65 mph, level and not accelerating hard.
I think this is something more symptomatic of 1990-1993 Q45s and their single pintle injectors and individual intake ports. The later 1994-1996 disc injectors and intake path modifications seem to eliminate this tendency. I say this because I can drive either of my under 60K 1995 Q45s like a grandma in D with no problem with light throttle at those speeds. But I don't..
Almost always in 3 until 60 to 65 mph, level and not accelerating hard.