'96 Q Erratic Shifting

[mtzgr777]

I've been having this problem for almost a month now. When the car is cold, it runs like a top. Once it completely warms up, there is this engine whine coming from the driver side of the engine bay that sounds almost like a super charger (Which unfortunately I do not have.) Also, after it warms up, it begins having erratic shifts. By erratic shifts I mean it has a hard 1-2 shift in which case the SLIP indicator light comes on, and from there, I have to rev it up to around 3900RPMS before it downshifts again. When I lay off the gas and step on it again, I usually have to rev it up to 3000-3500RPMS (depending on how fast I'm going) before it feels like it engages. In conclusion, the transmission runs great when cold, and starts having issues as soon as it warms up.

Some background Info:~Recently installed low-mileage used OEM TPS~Recently replaced fuel filter~Recently cleaned TB~Had transmission fluid flushed just the other day~Car has 143k miles

Any ideas?

[mtzgr777]

Just pulled codes, they are as follows:

- P0325 (Knock Sensor)

- P0733 (Gear 3 Ratio Incorrect)

- P1705 (Throttle Position Sensor)

[mtzgr777]

Bump! Any Ideas.....?

[Infinitiguy19]

personally the way I adjust the TPS is really want it so that when you press the gas it goes from "on idle' to "off idle" which changes the duty cycle of the IAC..

so all I do is change loosen the IAC and find the threshold and get it as close to that without going over.. Worked pretty well for me!

Remember a number is truly, just a number...

Thats what I was referring to when I said take to Wes on the TPS.

External FilterThe external filter is up front passenger side bottom near radiator [looks like oil filter with 2 hoses]. Not knowing your location (heat)I would still suggest an external trans cooler. As to rear main they all leak some after 100k as do all pre 94 valve covers. How much is it leaking since you have to pull exhaust, drive shaft, and transmission to replace? Have you had chain guides/oil chain changed--good time to replace front seal at same time.

They make replaceable add on trans filters with bypass valves, the factory sealed unit supposedly has one but then the material goes through. My point is most trans we see are already showing signs of low pump pressure and the last thing the torque converter needs is more output resistance.

You educated yourself that is what happens most places, though a pan may hold close to 3 quarts. The strainer / filter is fine enough to stop metal pieces [hard parts] but not dissolved [flaked off] clutch friction material. The redesigned 94-95 AT is longer lasting [20%] than the earlier models because of the progression of adding dual heat exchangers and external filters and better [higher temp] glue to hold the friction material to the clutches. The external filter should catch most of the material until it clogs then it's useless [bypass valve]. The problem with all transmissions is heat, which changes ATF and its break down product dissolve the glue. Changing the fluid alone will not solve all the problems since heat spikes can still warp the thin metal clutches [think of a stack of computer floppy disks] allowing the fluid to slip around these fine tolerance items. The transmission is designed to last through the 70,000-mile warranty 97% of the time with minimal maintenance. Getting it to last 140,000 miles depends on the owners extra effort. The problem is most damage is done in the first 10,000 miles {first summer] by heat this allows the minor slippage to begin which progressively allows it to get worse. This is why fluid exchanges can only halt future damage. Redesigning the transmission to run cooler in the summer is the best solution but you run into warm up problems in the winter because most people won't put up with waiting so what you have is a compromise. Trading off life for convenience. Lexus 400 opted for $9 a quart synthetic ATF that doesn't have the warm up problems and better summer cooling, Nissan did not feel that 150-200,000 mile transmissions were cost effective for dealers or company. Since Americans were only use to 60,000 mile units [Ford & Chrysler]. You must remember that the average warranty was 3 years and 36,000 miles then and now for many domestic lux autos the warranty extensions to 70k was unheard of; now that many are going to 100k syn fluids are making it easy.... except for heat!

Thats the external filter I was talking about.

Knock SensorsMy 1994 Q45 recently developed a sputtering problem, which has ultimately resulted in a serious power loss and stalling problem. Upon a visit to what this club has indicated is a highly reputable dealer (Denville Infiniti - in NJ), they tell me it is a bad knock sensor to the tune of $1000 P&L to replace. Is this a problem item and how does one prevent a re-occurrence? I always run Premium, with Techron per the recommendation of Q45Man. The knock sensors fail from overheating [9 out of 10 times]or the harness get corrosion from leaks making an intermittent. Have you every seen the temp sensor rise above the middle any time? Even 10%? The knock sensors are just contact microphones, the expense is taking the plenum off to get to them. While its off have the under plenum water hoses changed and any of the others that look weak. Make sure they replace the lower runner gaskets as they will leak air and cause a bad idle. Great time to have the plenum and its runners cleaned inside with a brush and solvent. What I'm suggesting may add a few hundred dollars but you won't have to pay for plenum removal{$500} if a hose starts to leak a month later. While they have it apart PVC valve and hoses, Just examine all the things under the plenum and you will decide its easier and cheaper to do it one time.

80-120k is the most expensive period unless something major goes later. It seems everything needs changing but it never cost as much as a new one. How is water pump? I worry when knock sensors fail because lets just hope it was a bad one and not heat!

If the car ever overheats [above the 1 o'clock position.....260-270 F]you can be assured that the knock sensors will be exposed to 350-400F which will crack the plastic surround, which will then modify the characteristics of the contact microphone....what a knock sensor is. Also plenum hose leaks may fill the engine valley with antifreeze which dissolves the dirt/oil film, this in turn can cause corrosion of the microphone connectors and harness. The 2 knock sensors are sold for $150 each plus harness. Also the ECU will record a code [most of the time] if it notices something wrong but!!!!! it will not trigger the check engine light....so you must be alert to the knock sound or general loss of some performance. If one or more sensors are not heard from the ECU will invoke a less aggressive timing mode which will drop power by 20% limiting peak horsepower to around 200, this will lengthen 0-60 by 1-1.5 or more seconds which you should be able to feel.

Knock Sensors

PRICING/MAINTENANCE COSTS3328 I received a couple of inquiries as to how we do business and the discounts we offer so I will explain to all the new members we have out there. Infiniti of Scottsdale offers 25% off of true MFG. list prices on parts & accessories to all members. What do I mean by true MFG. list? Dealers are allowed to mark up the parts to whatever price they want. We use the factory book list price. Some dealers will use a "matrix" or a "bump" list, which escalates the list price to 10-30% over true list. I have been told horror stories by customers around the country of the prices certain dealers charge. How can we do this? It helps that we are the largest Infiniti parts warehouse in the country. I am the Wholesale Parts Manager for the store which allows me to discount the parts around the country. We do over $100,000 a month in sales to shops around the local area and around the country so I can extend this discount to club & internet members. Another perk is FREE UPS Shipping. We ship UPS Ground for free and will charge for AIR as requested. I can't charge you sales tax unless your in AZ or unless you want to drive out to pick up your parts. I try not to use this forum to blatantly sell parts. I offer the discount as a service to the members. I've been in the parts biz for 16 yr. so I know how expensive parts are. I plan on offering up some member only specials in the future. This club is growing by leaps and bounds. I was talking to one of the original members and it's just remarkable how big it's getting. And it's only getting bigger. And better. TJ Infiniti of Scottsdale 1-800-955-9181

http://www.intellichoice.com/ic2/ The following 94 Models were analyzed for maintenance and repair cost projected over the next five years at 12,000 miles per year.G20....... $10,959J30....... $10,923Q45....... $15,061

LS400..... $13,191SC400..... $13,934SC300..... $10,981

Audi A8..... $17,054JAG XJ12.... $19,675JAG XJS..... $20,883BMW 740..... $16,569BMW 750..... $16,903???A camary was $10k , Honda about $8500

Of course maintenance and repairs are only a third of the cost of ownership equation the full cost varied from $42,000 for a Q to around $60,000 for one of the JAGs. Surprisingly the LS and Q were tied due to the lower depreciation of the LS. The insurance cost varied wildly with the JAGs being highest!

Something that might scare you.

6596 94 Q45 Transmission -Infiniti Hard Shift One thing to check when you have a hard shift problem is the Throttle Position Sensor (TPS). Should have .5 volts coming out of it, anymore and it could be bad. If the TPS is malfunctioning it will cause the engine and the transmission to not work in synch, causing the trans to shift hard. Sometimes causing the wheels to chirp. Something to check if there is nothing wrong with the transmission.

Some more about the TPS.

This was all in the link I showed you with the hundreds of documents.

Merry Christmas.

[mtzgr777]

Thank you once again, Paul! Merry Christmas

[Q45tech]

Actually back then [0.5 volts] I didn't understand the criticality of precise quoting here.

At hot idle the TPS voltage should be NO MORE THAN 0.45 volts.

The TPS generates the idle plus 9 different voltage plateaus for ecu and tcu which many call load factors and determine which cell group the ecu looks to acquire preprogrammed data.