Gear shifting is hesitating on automatic transmission.

[coolman]

I have a 1994 Q45 automatic transmission. When the engine is cold (first 7 mins of driving the car), the transmission hesitates and sometimes do not want to shift from 1st gear to the higher gears. The engine will rev upto 3000rpm and still be on 1st gear. After about 10-15 minutes when the engine is hotter, the car slowly returns to normal operating conditions with the gears shifting normally. I also smell gasoline while sitting in the driver's seat.

My question is what could cause this problem and what should I get my mechanic to replace or fix? Is it the fuel pump, fuel control, fuel relay? Or, do I need a tuneup? I recall using the Costco gas for about 3 weeks and noticed the problem. I am now using Shell gasoline.

Thanks,

[maxnix]

I have a 1994 Q45 automatic transmission. When the engine is cold (first 7 mins of driving the car), the transmission hesitates and sometimes do not want to shift from 1st gear to the higher gears. The engine will rev upto 3000rpm and still be on 1st gear. After about 10-15 minutes when the engine is hotter, the car slowly returns to normal operating conditions with the gears shifting normally. I also smell gasoline while sitting in the driver's seat.

My question is what could cause this problem and what should I get my mechanic to replace or fix?

Transmission maintenance history?

Need to read a few posts about operating temperature.

Have you done any under plenum work?

[qship96]

How many miles on transmission? color and level of fluid is? Last time transmission fluid changed was? Without these answers, impossible to determine if you have a small problem, or a $3000 one headed your way

[coolman]

Here are the answers to some of the questions.

- I have about 208K miles on the car.- The color of the transmission fluid is reddish pink and is full.- The transmission fluid was probably last change 3-4 years ago.- I do not know what a plenum is and I bought this car used a few back.- I bought this car used and don't recall any transmission maintenance other than changing the fluids.

It runs ok when the car temperature is a normal operating mode, but when called it exhibits these problems that did not exist before.

I performed the self-diagnostic which requires stepping on gas pedal, changing drive to D, 3, 2, then 1 and rotating the trip button counter clockwise. The display only shows "AT Check" and nothing more.

Thanks,

[maxnix]

- The transmission fluid was probably last change 3-4 years ago.- I do not know what a plenum is and I bought this car used a few back.- I bought this car used and don't recall any transmission maintenance other than changing the fluids.

It runs ok when the car temperature is a normal operating mode, but when called it exhibits these problems that did not exist before.

First, you need to download and read the FSM.

http://www.nicoclub.com/FSM/Q45/

Then you need to read some of the previous posts on transmission maintenance.

Do you know if the last change (it is now due for another) was a complete mechanical ATF exchange with a pan drop and filter replacement? Maybe just a drain and refill? Is there an auxilary ATF cooler on the car?

At 208K, hope you have the $3K saved for transmission replacement and other associated items like the rear engine seal, turbin snesor if needed, and 3rd motor (transmission) and exhaust hangers.

Misbehavior of systems before reaching operatiing temperature not really a valid issue.


Modified by maxnix at 2:43 PM 3/26/2008

[qship96]

I would drop pan, change both internal screen strainer and EXTERNAL filter and fluid and see if there is any improvement- if not,maybe it is just getting old and tired

By the way, anyone know how many 94-96Q original transmission make it much past 225,000 miles?

[Q45tech]

Very few in our experience make it to 225k without serious previous ATF changes and mainteance.

[coolman]

maxnix,

It does not have a ATF cooler. Should I get one of these and what are the benefits?

I got the ATF fluids replaced at JiffyLibe. So, I think it was just a change of fluid only.

[maxnix]

maxnix,

It does not have a ATF cooler. Should I get one of these and what are the benefits?

I got the ATF fluids replaced at JiffyLibe. So, I think it was just a change of fluid only.

Many as ATF temperature is stabilized and reduced under demanding operation. Read some of the previous posts, including all by Q45tech. Might be too late for the one you have now. It's not climate, but hills and high speed.

So you don't know if it was a drain and refill or a mechanical excahnge. A call should clarify it for you. In any case, 4 years (and how many miles?) is plenty. Bet they didn't drop the pan and replace the screen.

[coolman]

The ATF service done at JiffyLube about 4 years ago is simply a fluid change only, just like a radiator flush. Nothing mechanical was replaced or fixed.

Good news though. I did a search on this forum and someone said they fixed the same problem I am experiencing by adding more ATF fluids. So, I bought Lucas Transmission Fix 24 oz at Wal Mart and added to the Q45. After about 8 miles of driving, the car and transmission is back to normal. It no longer exhibits the hessitation and gear shifting issues. I can now accelerate quickly without problems. I hope nothing was seriously damaged by having low ATF fluids. I also plan to top off the ATF fluid since this Lucas Transmission Fix is just an additive and not ATF fluid.

Previously, I did check the ATF fluid dip stick and it shows it is full. I then checked a second time making sure the car is level to the horizon (not on a drive way or incline) and kept the engine running. I found out that the ATF Fluid levels were very *low*. This is probably why I was not able to spot the low ATF fluid levels. Is there a trick on consitently and accurately checking the ATF fluid levels?

I will look into the ATF Cooler. I will have to look on how much it will cost for parts and installation.

I also bought a K&N pre-oiled filter that I plan to install. I plan to keep this Q45 for a few more years, so I plan on maintaining it as much as possible.

Thanks,

[maxnix]

1.) The ATF service done at JiffyLube about 4 years ago is simply a fluid change only, just like a radiator flush. Nothing mechanical was replaced or fixed.

2.) So, I bought Lucas Transmission Fix 24 oz at Wal Mart and added to the Q45.

3.) I will look into the ATF Cooler. I will have to look on how much it will cost for parts and installation.

4.) I also bought a K&N pre-oiled filter that I plan to install. I plan to keep this Q45 for a few more years, so I plan on maintaining it as much as possible.

1.) So you don't know exactly what was done. Glad that is certain now.

2.) Lucas bad, Lube Guard Red and most sythetic ATF good. Better schedule another mechanical fluid exchange soon. No mention of fluid color nor its condition.

3.) Less than $60 from summit.

4.) Take it back now! Us only OEM paper! Cheaper and more effective.

You need to pull up a chair and read the previous posts, particularly by Q45tech. You will save a lot of money by purchasing only components that work (98% are OEM) and budget for a pro-active preventative maintenance program so you will enoy the next 150K miles.
Modified by maxnix at 6:22 PM 3/28/2008

[coolman]

The color of the ATF fluids before I added the Lucas Transmission Fix was pink and clean looking.

I did some searching on this forum and someone said the 94-96 Q45 has a radiator with 2 transmission coolers on each end that works pretty good. The other Q45 year models did not have this 2 coolers on each end. My questions is since I have 2 good transmission coolers already built in and just replaced my radiator with original OEM parts a few weeks ago, do I really need an additional ATF cooler? If so, is there a way to use both the already installed 2 trans cooler built into the radiator and the ATF cooler at the same time? I may decide to install a transmission temperature gauge so that I can monitor things.

Thanks,

[Haitian_King]

Here are the answers to some of the questions.

- I have about 208K miles on the car.- The color of the transmission fluid is reddish pink and is full.- The transmission fluid was probably last change 3-4 years ago.- I do not know what a plenum is and I bought this car used a few back.- I bought this car used and don't recall any transmission maintenance other than changing the fluids.

It runs ok when the car temperature is a normal operating mode, but when called it exhibits these problems that did not exist before.

I performed the self-diagnostic which requires stepping on gas pedal, changing drive to D, 3, 2, then 1 and rotating the trip button counter clockwise. The display only shows "AT Check" and nothing more.

Thanks,

Not to sound like a jerk, but the steps you posted in the diagnostic are a bit backwards. "AT Check" should show at the beginning of the diagnostic process, anything after that would either be an "OK" display or some sort of code that can be deciphered in the FSM.

When I was worried about my transmission, I added about half a bottle of the Lucas stuff on the strength of the advice of a well known and trusted (but will remain anonymous) NICO board member and suffered no adverse effects. One thing I noticed is that even after the pan drop/drain & fill and the BG mechanical exchange I didn't get much of a dfference and I still worried. I changed my spark plugs and replaced a leaky ATF pan bolt and the transmission shifts way better. 1-2 is fairly smooth and 2-3 is great. MUCH better than before.

Maybe it's not even the transmission. That's what it was in my case. I almost replaced my near virginal 90k transmission because of it.When was the last time the engine was REALLY taken care of? It may end up cheaper than a whole new transmission.

About the transmission cooler, it's like $50. From what I know about it, it can keep your fluid about 15 degrees cooler which will definitely prolong life.

Not a bad investment eh?

[coolman]

Haitian_King,

The Transmission self diagnostic procedures says to turn off engine and set to OFF position with the car keys and then shift to "D". However, in the OFF position, the 1994 Q45 has no DC electricity feeding in which is needed since my car requires depressing the brake pedal while shifting from P to D. There is some electronic lock preventing the shift unless you have the brake pedeal down and this electronic lock does not work in the OFF position when no DC electricity is powering the electronic lock.

Instead, I tried to turn trip reset knob counter clockwise and held it there while starting the engine. The display now says AT Check. I then shifted from P to D while brake pedals are depressed and now display says OK. This procedure I made up seems to work. Can someone verify this?

Also, can someone verify that I still need a ATF Cooler. My brand new OEM radiator already has a transmission cooler built into it. Isn't this sufficient?

Yesterday, I added 2.5 quarts of Mobil 1 ATF Synthetic ($7/quart at Kragen). The trans dip stick now reports it as over filled, but that is ok. My trans shifting and driving is all back to normal. About a few weeks ago, I bought a new OEM radiator assembly from infinitipartsusa.com (it includes the transmission cooler sections too). I think the car repair shop emptied the transmission fluids and either put in cheap grade ATF fluids or did not fill it to the correct levels. I am not blaming the car repair since I did experience these problems before. Probably my fault for not knowing how to correctly measure the ATF fluid levels and not knowing about ATF Additives/Synthetic fluids.

Thanks,

[qship96]

If your transmission has made it to 208,000 miles without any extra add on cooler, why would you think it suddenly needs one now? You have got good life out of transmission at your mileage, and I would not worry about adding an auxilliary cooler at this stage of the game.

New radiator is great, the only other thing I would consider doing is to replace the existing external transmission filter located behind the radiator near the battery if this has never been replaced, and continue to exchange the ATF at 25-30K miles from this point on.

[maxnix]

The color of the ATF fluids before I added the Lucas Transmission Fix was pink and clean looking.

I did some searching on this forum and someone said the 94-96 Q45 has a radiator with 2 transmission coolers on each end that works pretty good. The other Q45 year models did not have this 2 coolers on each end. My questions is since I have 2 good transmission coolers already built in and just replaced my radiator with original OEM parts a few weeks ago, do I really need an additional ATF cooler? If so, is there a way to use both the already installed 2 trans cooler built into the radiator and the ATF cooler at the same time? I may decide to install a transmission temperature gauge so that I can monitor things.

They are really better understood as ATF heat exchangers in that if the ATF is under ~200° F there is no cooling.

The auxiliary ATF cooler can be added in series with the two heat exchangers.

[Haitian_King]

Haitian_King,

The Transmission self diagnostic procedures says to turn off engine and set to OFF position with the car keys and then shift to "D". However, in the OFF position, the 1994 Q45 has no DC electricity feeding in which is needed since my car requires depressing the brake pedal while shifting from P to D. There is some electronic lock preventing the shift unless you have the brake pedeal down and this electronic lock does not work in the OFF position when no DC electricity is powering the electronic lock.

Instead, I tried to turn trip reset knob counter clockwise and held it there while starting the engine. The display now says AT Check. I then shifted from P to D while brake pedals are depressed and now display says OK. This procedure I made up seems to work. Can someone verify this?

Also, can someone verify that I still need a ATF Cooler. My brand new OEM radiator already has a transmission cooler built into it. Isn't this sufficient?

Yesterday, I added 2.5 quarts of Mobil 1 ATF Synthetic ($7/quart at Kragen). The trans dip stick now reports it as over filled, but that is ok. My trans shifting and driving is all back to normal. About a few weeks ago, I bought a new OEM radiator assembly from infinitipartsusa.com (it includes the transmission cooler sections too). I think the car repair shop emptied the transmission fluids and either put in cheap grade ATF fluids or did not fill it to the correct levels. I am not blaming the car repair since I did experience these problems before. Probably my fault for not knowing how to correctly measure the ATF fluid levels and not knowing about ATF Additives/Synthetic fluids.

Thanks,

Yup. You're doing it incorrectly.

Do you see a button in the top right corner of the shifter plate that says Shift Lock? Depress that button and you'll be able to shift the lever without depressing the brake.

The engine shouldn't be running to perform this test.

[Q45tech]

The AT check just test electronic sensors and connections/signals has absolutely nothing to do with MECHANICAL conditions inside transmission.

The FSM describes how one measures ATF pressures with gauges and a drive test proceedure to determine the mechanical health.

Anyway, 200k is very good life for any AT with a V8 in front of it. Mercedes/BMW wishes they could do as well.

The LEXUS V8 AT is the most robust in the industry and those start to go a 250-275k and an annual pan drain of ATF is required to replenish additives [3 out of 10 quarts].

[coolman]

The "shift lock" button is permanently pressed downward and will not come back up. So, I think this button is stuck or not working. It doesn't look like a button. It looks more like a piece of plastic plate or something.

Also, I just ordered the B&M 70268 for $50 total from Amazon.com (no tax and I got Amazon Prime for free shipping). I plan on getting a mechanic to install it since I almost never work on cars. If my transmission can last longer with this cooler, than it will be worth it.

Also, my air box which contains the air filter has 1 of the 4 metal clips broken off. I would like to replace it with an Intake Air mod. What kind should I get and how easy is it to mod it myself?

Thanks,

[Haitian_King]

The "shift lock" button is permanently pressed downward and will not come back up. So, I think this button is stuck or not working. It doesn't look like a button. It looks more like a piece of plastic plate or something.

Also, I just ordered the B&M 70268 for $50 total from Amazon.com (no tax and I got Amazon Prime for free shipping). I plan on getting a mechanic to install it since I almost never work on cars. If my transmission can last longer with this cooler, than it will be worth it.

Also, my air box which contains the air filter has 1 of the 4 metal clips broken off. I would like to replace it with an Intake Air mod. What kind should I get and how easy is it to mod it myself?

Thanks,

http://www.q45.org/trannycooler.html

That link is to the guide for installing the cooler. I guess it's one of the easier jobs to do on the Q. Probably a two hour affair, judging from the article. If your mechanic doesn't charge much, I guess he can do it. But if he gets pricey, it might be more cost effective to DIY.

For the air intake mod, some members have used a K&N CAI, but that's in debate. Tech and Maxnix believe that the OEM one is preferable to any aftermarket. It's not restrictive at all. Maybe you could just get a new "box" from a donor Q.

From what I've seen here, there isn't much benefit from modifying the stock intake. The best I've seen/heard is a different sounding engine. I hear it makes it sound "meaner".

[maxnix]

Also, my air box which contains the air filter has 1 of the 4 metal clips broken off. I would like to replace it with an Intake Air mod. What kind should I get and how easy is it to mod it myself?

The best "mod" you can make to your air box is to replace the clip or that part of the air box.

Do read some previous posts before you start throwing money away.