Forgive my ignorance... Please tell me, what is a TCU?

[heatherin951]

I am new to this site. I joined in attempt to educate myself and figure out what is wrong with my beloved Q45 (1990, and cherry!) A recent thread titled "Transmission misbehaving", describes exactly what my car is doing. I have read other threads as well. many point at revolution sensor or fuel regulating sensor. Anyway, I just want to know what a TCU is. Also ECU, and TPS.I'm sure I sound ridiculous. But... it is what it is.I am a single mom. My son started kindegarten today. I have a good mechanic who is the person that sold me the car. But he is out of the country for 11 more days.I have an in at the local Infiniti dealer. (a client of mine is best friends with the general manager) so i dont think I will get screwed if I take it there. I just don't have the kind of money dealers charge. I have a very mechanically capable friend that can work on it. But I don't have a freakin repair manual.Also...in case any of you wonder... I had the transmission fluid, filter, and gasket changed last week. The fluid DID smell burnt. Seemed to be pertinent info in the threads I read.Any advice is so appreciated.Heather

[AZhitman]

Hi Heather, welcome aboard!

TCU = transmission control unit

ECU = Electronic control unit (the "brain" of the car)

TPS = Throttle position sensor... typically goes bad on the early Q45s.

And, last but not least, here's your factory service manual: http://www.nicoclub.com/FSM/Q45

You'll have to make do with the 94 manual, we don't have the 90-93 posted yet...

Hope your mechanic friend didn't charge you too much for the car... an early Q is NOT a good car for those on a limited budget, she's a finicky beast with expensive parts...

OK guys, let's find Ms. Heather a new best friend in SoCal who will help her out with the Q. There's a lot of you out there, let's do what we all came here to do.

[Jesda]

Jerry Tucker's old shop in San Diego does excellent work. How far are you from there? I'd take it to his shop for big ticket items.

Otherwise, like stated above, I honestly don't think an old Q is a good choice of transportation for a mom. A Maxima is a more practical combination of fun and reliability.

If you can turn a wrench and have the willingness to learn, it can be a fun hobby. DIY offsets the high parts and maintenance costs.

[heatherin951]

Thanks so much for the definitions and manual link!!!!I did not expect such generosity and kindness. Jesda...I am learning about the upkeep on my girl. I recently found out the cost of changing spark plugs..(yikes)BTW....although grateful for the suggestion...San Diego is is 90 miles.I would love it if someone knew a good Q tech for me locally.I am a woman that has suffered at the hands of shady mechanics in the past.

[sublime187]

Certainly the Senior Inifiniti technician who performed your pre-buy inspection informed you of the condition of your TPS. What did the Infiniti dealer service history that you requested before purchase say about your TPS? LOL, just kidding. Welcome to the forum

[heatherin951]

Sublime....brat!!! you had me there for a second.....

[maxnix]

BTW....although grateful for the suggestion...San Diego is is 90 miles.I would love it if someone knew a good Q tech for me locally.

Precisely why Jerry Tucker is in your neighborhood. Competent independent techs to work on early G50. If you think 90 miles is too far for major work, try Mantua, NJ and Atlanta. A Q45 is not a Chevy!

Now, have you read the article on the Timing Chain Guides in the sticky above?

[maxnix]

Certainly the Senior Inifiniti technician who performed your pre-buy inspection informed you of the condition of your TPS. What did the Infiniti dealer service history that you requested before purchase say about your TPS? LOL, just kidding. Welcome to the forum

Sublime....brat!!! you had me there for a second.....

Actually, he's not! If you skipped that step, you better have at least an $8K cash kitty to catch up on deferred maintenance. As you read here, you will discover what ignorance about a cars condition and maintenance history can cost. Ignoring the deferred maintenance will just make your ride more expensive and short lived.

[96Qowner]

Give us a little more info on your symptoms. Do you get the clicking? And how about 3rd gear - does it stay locked in 3rd, or shift in and out at odd times?

There's a nice detailed procedure in the Manual for the transmission self-diagnosis feature. You can run that yourself. Keep us informed.

And welcome to NICO!

[maxnix]

There's a nice detailed procedure in the Manual for the transmission self-diagnosis feature. You can run that yourself. Keep us informed.

Yes there is, but it will only reveal electronic faults, not mechanical ones or wear and tear.

[oldmako]

Certainly the Senior Inifiniti technician who performed your pre-buy inspection informed you of the condition of your TPS. What did the Infiniti dealer service history that you requested before purchase say about your TPS? LOL, just kidding. Welcome to the forum

FREAKIN' HILARIOUS!!!

I was worried this place was spawning clones till the "LOL, just kidding..."

[AZhitman]

OK guys, we're pretty sure Heather comprehends the doom and gloom of owning a Q that hasn't been maintained to our standards.

But that's not helping her any.

Let's get someone to assist with the most glaring faults FIRST so she can at least have her transportation needs met.

THEN she can worry about getting it back to "tip-top" condition.

[maxnix]

Let's get someone to assist with the most glaring faults FIRST so she can at least have her transportation needs met.

First would be the timing chain guides and once again , Jerry Tucker is her best bet for inspecting and verifying. He also would be teh best bet for determining what else in what order needs to be done, cash reserves permitting..

Reliable and safe transportation is what we are all about!

[heatherin951]

Ok, more symproms...

It won' shift out of second until after it is warmed up. If, while it is "misbehaving", I let take my foot off the pedal, it suddenly is in neutral. It does not slip. Once it will shift into 3rd, its typically ok for the rest of the day. This has been going on like this for a week now. First thing I did was have the fluid, filter, and gasket changed. The fluid was burned and there was sludge in the pan. No metal shavings to speak of, and i cleaned the pan myself.I should also mention that I recently had a loose connection in the throttle body sensor. (I think that is what it is called). It is still loose at times I think because about once a day when I start it it runs rough with the engine light on . It stops this after I break the first time. Make sense?Please no thinking I am unworthy of my Q guys, I am just trying to get my kid and I through our day. I do know the importance of maintaining a vehicle as my Dad was relentless about this. (he lives in Idaho now though)

BTW...The timing chain was replaced less than a year ago.

[maxnix]

Great news on the timing chain!

Now, about the ATF, was that a drain and refill or a mechnical exchange of all the ATF as is done with a BG or Sun machine? Any chemical flush like BG Quick Clean for automatic transmissions?

Did they replace the interior filter and O ring? What did the filter look like?Hopefully they used a new OEM gasket and one-time use bolts when the reinstalled the pan.

Did they look at the PS fluid?

I would seriously consider saving for a Nissan rebuilt transmission and auxiliary ATF cooler, and shopping for a 1993 TCU with first gear start on our Infiniti Parts Classified Forum.

Then we can get to the suspension and brakes.

[heatherin951]

It was just drained and refilled. The filter was actually not too bad. We did not change the interior filter. The gasket was an OEM.

[96Qowner]

Any improvement after the drain and refill? I don't like the news about 2nd and slipping out of gear. You might consider another flush, this time through an exchange machine - not terribly expensive.

The typical sign of a failed/failing transmission is refusing to go into reverse. Any trouble with that?

[AZhitman]

Actually, this sounds MORE like a TPS than anything else, I went through it with my Q.

Let's get a Consult hooked up to the car and check the TPS, it's easy to tell if it's bad.

If the car doesn't get the proper reading from the TPS, it can't tell what gear it should be in and will "misbehave" accordingly.

[heatherin951]

No problem at all with reverse.

I am going to have my capable friend read this, I am off to work. (getting a ride, not willing to drive her like this anymore)I will check back in later.Thank You so incredibly much for giving me some direction!

[96Qowner]

Here are a couple past threads about the Throttle Position Sensor (TPS):

zerothread?id=267914

zerothread?id=347575

[maxnix]

I am off to work. (getting a ride, not willing to drive her like this anymore)

Very wise decision as further use in this condition will just exacerbate the problem.

[96Qowner]

A couple more TPS threads, including AZhitman's:

zerothread?id=204890

zerothread?id=71979

[Razi]

Yes, I think you should find a mechanic to hook up a consult and see what's going on.

My dad went to the Infiniti dealership in Riverside recently, the mechanic there seemed to be pretty competent about the Q45.

[heatherin951]

Any chance you could get the name of the mechanic?I will likely take it there.Thanks!Heather

[maxnix]

Just ask that the Senior Infiniti Technician work on the car.

On this Forum, a Senior Infiniti Technician means one that was trained on the G50 when it was introduced in 1989. Your Q45 is a G50.

[heatherin951]

update...

New TPS is installed and is still being adjusted as we speak.

The manual was a lifesaver!

My fingers are crossed that my Black Beauty will be back to her old self.

I will post another update as soon as I know.

[AZhitman]

update...

New TPS is installed and is still being adjusted as we speak.

The manual was a lifesaver!

My fingers are crossed that my Black Beauty will be back to her old self.

I will post another update as soon as I know.

You ROCK, girl!!!!!!!!!!!!

Keep us posted.

AND we want pics of the car when you get time!

[heatherin951]

You bet i will!

TPS still not adjusted properly. Still trying.

[maxnix]

Oooooops!

Senior tech at the dealer?

[heatherin951]

Sooooooo...

Once the TPS was adjusted properly, she was perfect! Took her for a long test drive. The next morning another test drive. Still perfect. 2 hours later i drove too work. 5 miles down the freeway, I had to merge and she kicked down. Wouldn't come out of second gear after that!

I took her to a shop I already knew of. What I didn't know was that the owner (who has a great reputation) owns a 94 Q. (and its a beauty) Long story less long, according to the computer he hooked her up to, there is nothing wrong with her!!!! The TPS is perfectly adjusted, the car's computer is telling her to shift, etc. The mechanic was totally stumped.

My regular mechanic, the one that sold her to me, and knows her inside and out, gets back into town on the 5th. Any thoughts as I wait in limbo until then?