1990-1996 Q45 Buyers' Guide

[AZhitman]

BUYING ADVICE FOR 1990-1996 INFINITI Q45

Congratulations! You are looking at one of the finest cars ever created. However, they are not without shortcomings. Here are some major stats and facts about the 1st generation Q45:

•They came stock with the VH45DE, an all-aluminum, 4.5 liter engine rated at 278 horsepower and 296 ft/lbs. of torque. This is also one of the first cars to use VVT (variable valve timing), which controls the amount of intake valve overlap thus optimizing power. That said, when they rated the VH45DE in 1989 in Japan, they rated the engine WITHOUT VVT. In Japan, if an engine is rated over 280 horsepower there is a stiff tax so to avoid the tax they rated it without VVT installed. It is important to note the 1996 Q45 does not have VVT because of emissions regulations. Thus, the engine produces closer to 310 horsepower and 330 ft/lbs of torque.

•These cars use one of the best paint processes in history. You will be very hard-pressed to find a Q with bad paint, unless it was completely abused. They are also very resistant to rust. That being said, you must be cautious of Q’s that have lived in the North or the Northeast for some time. These must be checked for rust on the undercarriage as well as the exterior.

•It was the first car to be offered with a FULL ACTIVE SUSPENSION. It is a computer-controlled system and a network of VERY COMPLEX hydraulic actuators and accumulators, and there is literally no roll inside .5g. They have that built in so drivers do not overdrive their tires. New active computers can be purchased from Japan to make the active ride even better.

•It came with dual exhaust, three-way catalyst system with ultra high-flow cats. Any exhaust modifications past removing and replacing the rear resonator is a measure in futility. There is no power to be found in the exhaust system and new catalysts are not recommended as they will not flow better than stock or last as long.

Variations of the Q45:

Q45: Q45 with standard optionsQ45a: Q45 with a full active suspensionQ45t: Touring model Q45, which has upgraded wheels and a rear sway bar.

Differences between the 90-93, 94-96; and problems associated with them

90-93

The first generation Q45 is said to be the best of a PERFORMANCE-LUXURY sedan, where performance is first and luxury is second. Real leather door panels, vinyl covered dash, some of the best plastics in the industry and not a hint of wood trim or anything like that. Everything was built for a purpose: No grill because it gives wind resistance, no wood trim and so on. There are many features that are only in the best of cars today. I dare you to find EVERY interior feature in 20 minutes in the first time you sit in a G50 Q. The car also came stock to start in 2nd gear to have really smooth starts and then when you drop it to 1st, it unlocks the fury of the engine.

NOTE: The 1993 Q45’s started in 1st gear, as well as the years that followed. The main problem with the 90-93 Q45’s is the plastic timing chain guides. This is a well-documented problem, but not well-known to many owners. A full description of this problem can be found in our Timing Chain Guide Article.

Other common issues:

Please see Infiniti Technical section for more information.

•Fuel Injectors - For some reason the injectors are weak on this car. Four of them can be replaced with the plenum on (the silver “spider” atop the engine). If the engine starts to shake at idle and you don't get a check engine light, most likely it is an injector.

•Mass Air Flow sensor connector (MAF) - Corrosion occurs on the connectors of the MAF and causes a false reading and ultimately a vibrating idle and drivability issues. An easy way to test this is to wiggle the connector at idle, and if the idle changes then you must clean it.

•Transmission cooler - This is very prevalent on the 90-93. The stock cooler is more of a “heater” and thus is ineffective. An external cooler is recommended to prolong life, as the main killer of a transmission is heat and not wear. The recommended cooler is a B&M part number 70268, and can be had at Summit Racing for about $60. See http://www.nicoclub.com/subpages/infiniti-tech.shtml]Transmission Cooler [/URL]for installation instructions.

•Knock sensors – This is not really a major problem on the Q45, but if you’re buying a car with more than 100,000 miles on it, it is something to be aware of. The casing of the knock sensors eventually crack and fail (usually around 120k) and this causes the computer to retard the timing 5 degrees or so, causing decreased acceleration. If this is the case, they need to be replaced. The plenum must be removed for this job.

94-96

Everything from the 90-93 is applicable except for the following changes:

•The timing guide issue is not applicable; they came with the updated metal-backed guides.

•A softer suspension for a better ride. Some owners say the 90-93 handles better as a result, but in my opinion the 94-96 still has very stellar handling.

•Softer seats and heated seats as well as other interior accents.

•Traction control, which helps handling in poor conditions.

•Exterior styling was changed with a small grille and some other minor things.

•Power headrests and tilt-down mirrors in reverse.

•1st gear starts were now standard, and a lowered 1st and 2nd gear to maintain smoothness.

Basically all of the same issues EXCEPT the guides are there, except not really as bad. Injectors were restyled and are more reliable but they still fail, especially in areas with oxygenated fuel and ethanol added. California and Arizona are the worst. In my opinion, these are overall the best Q45s to get because of the better reliability and lower cost to own, and more luxury. Note here that I own a 1994 Q45. However, it has not by any stretch of the imagination undergone drastic changes; it’s still very much a driver’s car.

The 96 model year got OBDII and lost variable valve timing, so it is much closer to 278 horsepower.

What to look for when buying a 90-96 Q45.

Exterior

First thing is to visually inspect the exterior. Look for variations in the paint (there should be little orange peel, if any). If there is, it has probably been repainted at some point. This is bad because, unless the owner spent $4,000 on the paint job, it won’t come close to the quality of the factory paint.

There’s only one common rust area on the Q and that is on the rear, where the plastic bumper meets the rear quarter panel. It’s uncommon to see a Q with exterior rust and if there is rust, run away, because it probably hasn’t been maintained well. However, if it is just that small spot I wouldn’t worry too much.

Interior

Just make sure everything works. Don’t worry about any STOP LAMP INOPERATIVE messages or something similar to that because they can all be fixed easily. Be concerned if it does say TRANSMISSION MALFUNCTION. Also see if the “Check Engine” light is on.

Something I’ve noticed on many Q is the little interior lights go out. I have many out in my Q right now. They go behind many switches and there are tons of them. Another thing like that is the rear ash trays, most flop around and are broken. For non-smokers, this is not a big deal as visually you can’t tell unless you open the tray.

Engine

There are many things with the Q engine that can be easily inspected. A look inside the oil filler cap is worth 1000 words (or dollars). You need to really look down in there with a flashlight as far down as you can see, and you should only see cleanliness. If it’s black or really dark brown avoid buying the car as sludge in the engine will significantly shorten its lifespan, as well as decrease its power.

Check the engine oil. The level should be good and the oil a nice golden color if it has been recently changed. When you wipe it off, in the little round part of the stick, there should be no ‘goo’ there.

Other fluids: Brake fluid (should be clear; slightly yellow but it depends on the fluid they use); transmission fluid (red, and should NOT be brown or smell burnt, if it is then the transmission is on borrowed time); power-steering fluid (same as transmission fluid).

With the engine running at idle, you should feel no vibrations, it should run at about 650rpm fully warmed (just below the line between 500 and 1000). If it’s below this then the intake will need cleaning, and do NOT ADJUST THE IDLE SPEED, it needs to be corrected by cleanliness. You shouldn’t really hear much, you will hear some slight ticking of the injectors opening. It’s very soft and anything louder should be noted. The fan should show resistance when moved (engine off).

On the lift

Check for body damage, rust and other damage. Also check the suspension components, mainly the rubber bushings for leaking of silicone or cracking. They wear with age more than miles.

I hope this helps you in purchasing your new Q45. I hope it will save you as much time and money and hassle as it could have saved me and countless other members before the article was written. Be sure to come back to NICO with pictures of your new ride as soon as you get it and welcome to the boards.

Article composed and written by Wes Stinson aka elwesso (Q45 Moderator)with edits by Nick Zluticky aka 90Q45Blue

[maxnix]

Great summary.

Under the automatic transmission cooler section, let me suggest :heat exchanger" instead of "heater", although the latter could be argued to be correct upon initial cold start operation. The twin tanks on either side of the radiator are really to stabilize the ATF temperature from being too cold and hopefully too hot.

I would mention the addition of the external ATF filter also as being significant to extending the transmission life of the later G50.

[qship96]

And I would point out the q has no special resistance to rust,as most q`s that reside in the Balt/Wash area ,including mine, have rust both in the area you mentioned and in the rear dog leg areas of the rear door openings-while similar 90-96 ls400 and other lux cars from this era have ZERO rust-Infiniti failed here as far as I am concerned{THE biggest failure on the whole vehicle}

[dsagers]

[•It was the first car to be offered with a FULL ACTIVE SUSPENSION. It is a computer-controlled system and a network of VERY COMPLEX hydraulic actuators and accumulators, and there is literally no roll inside .5g. They have that built in so drivers do not overdrive their tires. New active computers can be purchased from Japan to make the active ride even better.

Tell me more about the New active computers purchased from Japan to make the active ride even better? Is this an after market computer?

[Q45tech]

I object to the blanket statement concerning weak fuel injectors since they only fail when exposed to non comforming non standard gasoline.E10, or oxygenated previously with MTBE before May of 2006.

The choice of gasoline is up to owner and where they or previous owners lived.

Why it is important to trace the location history of any old Q before you buy or accept the consequences.

Same with where you live now!

[d3funct]

+1 -- Sounds interesting!!!

[elwesso]

I object to the blanket statement concerning weak fuel injectors since they only fail when exposed to non comforming non standard gasoline.E10, or oxygenated previously with MTBE before May of 2006.

The choice of gasoline is up to owner and where they or previous owners lived.

Why it is important to trace the location history of any old Q before you buy or accept the consequences.

Same with where you live now!

Yeah but fact is in MOST of the country today is exposed to that gas and theres no choice.

[elwesso]

Tell me more about the New active computers purchased from Japan to make the active ride even better? Is this an after market computer?

basically from what I understand, its just a height controller. It doesnt really change the dynamics of the active per se, unfortunately.... Maybe someday I'll try and reprogram an active suspension computer.... RIGHT!

[Q45tech]

Most of the country is not ecurrently exposed to E10:

Gasoline containing up to 10% ethanol has been available in over 41 states for more than 10 years. Today, over 40% of the gasoline in the U.S. contains ethanol, and the percentage is projected to continue to increase.http://www.hawaii.gov/dbedt/in...n/e10/

40% is not most of the gasoline

Their will not be enough ethanol until 2012 or later to supply all [except racing fuels] with oxygenates.

The Australian's have a good idea what happens and what components need to be up graded for ethanol. Might be a good primer of redesign:

http://www.environment.gov.au/...s.pdf

[goody90q45]

The choice of gasoline is up to owner and where they or previous owners lived. Why it is important to trace the location history of any old Q before you buy or accept the consequences.

Same with where you live now!

Living in Sacramento I have no choice but to use E94 91 octane fuel. Looking at a chart from 2004, the closest state with no-ethanol fuel is Idaho. Not a bad drive. It's only a 2 day trip. I suppose during the winter that could be a tough drive so if I head due east rather than north I can get to Oklahoma in two days also. No ethanol-free fuel available in states in between in both directions.

I hate to drive that far and hopefully my chart is wrong. Does anyone know if ethanol-free fuel is available in Nevada (a quick 2 hour trip), Oregon (only 6 hours), or Arizona (6 hours)? I can be in Washington in 10 hours or Mexico in 9 hours if it's available there. How nice to be centrally located with so many options.

My apologies for being sarcastic but for 80% of us we have no choice. You get what you get. Driving across state lines to fill up your tank is not an option. I really don't want to move permanently out of state with my $4000 car so I can have good fuel available. I couldn't help but notice that clean fuel is available in Georgia, Florida and Mississippi. Convenient.

And yes, I've had to replace 4 injectors since I bought my Q two years ago.

[qship96]

my q has been run on mtbe then ethanol for its entire life {197,400 miles} no problems yet!

[greenwar]

Only one question! Why isn't this a sticky yet?

[elwesso]

Because ALL NECESSARY READING MATERIAL is already located in the HOW-TO section!

[Q45tech]

You can set up a mini gasoline reprocessing plant to remove water and ethanol. Use the ethanol to sell to moonshiners or add tequila flavoring to cover up the residuals. Easy to chill E10 and add more water and ethanol will fall out to bottom

Can you and friends drink 2 gallons of grain per week.