Q45. Feel it is slow, some problems. HELP

[svtgtr]

Hi there. im new to the forums. I have recently bought a 1994 q45 and love the ride. smooth yet luxary. THe problem is i feel that the car is kind of slow for a v8. Not sure if this is normal or not. At start off, if i give it gas, it doesn;t really move just makes a nice sound. Is there somehting wrong with the car? something need to be tuned or changed?

Also the display on the cluster ( the one on the bottom right corner where it shows the km's / miles u have done) comes on once and a while then turns off. Also i notice sometimes when it is damp weather, when i start the car, the car shakes, then i get a check engine light. If i jsut drive the car, the light will eventualy turn off and car will stop shaking.

What can i do to solve these problems? Thanks Andrew

[maxnix]

No mileage stated, no prevous maintenance history offered, so we have little to guide us.

Might start with changing all fluids and filters. What did the Infiniti dealer performed history you obtained prior to buying the car reveal? What did the senior Infiniti technician sho inspected the car reveal in his pre-purchase report?

[Scotte123]

Same issue for me Maxnix.

I have 179,000 miles on a very well maintained 94 Q. Recent issues with the car have been the fan clutch and tensioner pulley. Both went bad and robbed an incredible amount of power.

Car is still slow for a 94 q though. I have been checking out the site and realized my FP was failing. With this sites help I am changing it out. I have a question about the FPCU though. It seems I should change it at the same time just to be safe, however should I use a used FPCU or a new one? And shoudl the relay be changed too?

[maxnix]

If the FP is replaced early enough, FPCU is usually unaffected, and physical inspection can help guide you. However, an apparently fine one can develop an intermittent failure like one did on Q45tech's car which vexed him for about a year. Smart owners procure hopefully known good ones as spares. Dealer always requires new FPCU with new pump. New O ring is critical, as is careful even tightening of the pump flange. Read the post in IOM.

KS, KS harness and injectors should be the next to be verified to be in specification. If intake system is not pristine, time t o think about under penum hose job, VC covers, plugs and since you are there, KS and harness.

No maintenance history for yours either, so if regular mechanical ATF exchanges not evidenced, no auxiliary ATF cooler, regular filter changes and fresh fluids, we can only guess. Once eveerything is up to as new snuff, NICO ECU will give you some extra kick.


Modified by maxnix at 8:48 PM 6/2/2008

[Q45tech]

How slow is slow? What is zero to 30 and 60 use an accurate trained hand and stop watch. Measurements should be repeated 3-5 times and averaged to 0.1 seconds.

A frequent test I do is to lock transmission in 2nd gear and floor at 45 and stop watch 50-80 which averages 5.8 seconds on a 90Q with Nico ecu at 1100' AMSL at 70F.

[svtgtr]

My Q45 has 93 miles (150 000 km). Had the transmission fluid flushed, regualr oil changes. Recently changes oil filter. I seem to notice that in a nice cool day, the Qseems to have more power but when its hot outside, there is no power when i boot it. WHen i mean slow it takes like a good 4-5 seconds to get from 0- 40m/h in drive and thats when i push the gas. Also when its in Drive, is the gas peddle suppose to feel soft?

[elwesso]

definitely sounds like you need to look at KS, fuel pump, and other maintenance items... I wouldnt ever call a Q slow..

[svtgtr]

whats a ks? is the fuel filter still ok or should be changed? i put in 94 premium fuel in

[elwesso]

KS= knock sensor.

Id do a fuel filter at the same time you do your pump. I do fuel filter and air filter together every year..

[maxnix]

For parts, Joe and the crew are our friends.

http://www.infinitipartsusa.com

[goody90q45]

Also i notice sometimes when it is damp weather, when i start the car, the car shakes, then i get a check engine light. If i jsut drive the car, the light will eventualy turn off and car will stop shaking. What can i do to solve these problems? Thanks Andrew

Ohm your injectors on a cold engine and let us know the readings. They should all be 10.0-14.0. Have you pulled ECU codes?



Open your trunk lid and listen. Does it sound like a swarm of bees? If so your fuel pump is dying. The best next step is to change your fuel filter and check the fuel pressure. It should be in the 40psi range. You could also have a dying FPCU (in the background in the pic) and can check it by first inspecting the connection for burns, melting, shorting, etc., and then grounding the 3 speed fuel pump to run on high speed only. Run a jumper from the pin in the pic to ground. If she runs well it's the FPCU gone bad.



Your CEL and shaking at startup sounds like a dying injector (or 2) to me. Once the engine warms up does the CEL and shaking go away and the car run normal? Let us know what you find.

[Scotte123]

If the FP is replaced early enough, FPCU is usually unaffected, and physical inspection can help guide you. However, an apparently fine one can develop an intermittent failure like one did on Q45tech's car which vexed him for about a year. Smart owners procure hopefully known good ones as spares. Dealer always requires new FPCU with new pump. New O ring is critical, as is careful even tightening of the pump flange. Read the post in IOM.

KS, KS harness and injectors should be the next to be verified to be in specification. If intake system is not pristine, time t o think about under penum hose job, VC covers, plugs and since you are there, KS and harness.

No maintenance history for yours either, so if regular mechanical ATF exchanges not evidenced, no auxiliary ATF cooler, regular filter changes and fresh fluids, we can only guess. Once eveerything is up to as new snuff, NICO ECU will give you some extra kick.

Modified by maxnix at 8:48 PM 6/2/2008

The car has all new synthetic oil, the transmission has been flushed, the injectors have been flushed, new fuel, oil and air filter (K&N), new plugs. There is no aux transmission cooler (yet, but will be). Oil Filter changed every 3k miles, Air filter changed or cleaned as needed by inpection, fuel filter changed every 70k miles.

Car history, mother bought it new in 94. All service was performed as scheduled by the dealer until 125k miles. That's when I bought the car and started performing much of the maintenance myself. She got rid of the car because the performance had decreased significantly. By that I mean that by the seat of the pants it felt like a Lexus on acceleration. It won't spin a tire. It is definitely slower than it was at 90k miles.

Q45Tech, thanks for the input on timing the car. I am not experienced at it but will give it a try. I will check out the KS as well, that sounds very promising.

I saw a post from elwesso about timing chain stretch affecting the cam timing. Is this something I should be worried about and explore (I hope not).

Thanks to all of you for the input. It is very much appreciatedl.

[Q45tech]

For the past 10 years I have changed my fuel filter annually [every 15-20k] everytime I've weighted the old filter after blowing out residual fuel there is significant dirt left in the filter usually more than - 28 grams/1 oz.

70k interval is mechanical child abuse

[svtgtr]

Ya, after engine warms up, the shakin of the car goes away, check engine light goes alway also. this only happens sometimes. aint a regualr thing. As for chekcin ohms and stuff, i dont got the tools to do that. i will get a mechanic to do that when i bring it in for regualr checkup or when the car dyes lol.

Your CEL and shaking at startup sounds like a dying injector (or 2) to me. Once the engine warms up does the CEL and shaking go away and the car run normal? Let us know what you find.

[elwesso]

I never remember posting something about chain stretch causing performance decreases, because that is not true!! If you know where it is, let me know so i can correct it!

[svtgtr]

I never remember posting something about chain stretch causing performance decreases, because that is not true!! If you know where it is, let me know so i can correct it!

um im not sure waht this means

[qsiguy]

You can check the knock sensors using the Q's built in diagnostics at the ECU. Check the FSM (Factory Service Manual) for instructions. You can also check them with an ohm meter. When I had 1 bad KS my car was down about 70 whp w/stock ECU verified on the dyno against a NICO ECU (which was effectively ignoring the KS) on the same dyno session.

Might also try running a can of BG44K injector/fuel system cleaner through it.

[maxnix]

The car has ... air filter (K&N), new plugs.

Replace it with OEM stock. You may have to clean your MAF sensor wires. per article at Q45.org.

You should check MAF connection also.

SHAME on the dealer for letting the car's performance deteriorate like that!

[Scotte123]

For the past 10 years I have changed my fuel filter annually [every 15-20k] everytime I've weighted the old filter after blowing out residual fuel there is significant dirt left in the filter usually more than - 28 grams/1 oz.

70k interval is mechanical child abuse

LOL... Sorry, I'm a dyslexic typer. I've only had the car for 50k miles and already changed it twice (averaging about 25k per fileter). I don't know what the factory recommends but I know it was changed regularly by the dealer before I got the car.

I will ohm the injectors and KS and get back to you guys. Going out of town so it will be a couple of weeks before you see my here again.

Thanks everyone for your help!

[maxnix]

LOL... Sorry, I'm a dyslexic typer. I've only had the car for 50k miles and already changed it twice (averaging about 25k per fileter). I don't know what the factory recommends but I know it was changed regularly by the dealer before I got the car.

Factory is 30K, but it should be done annually/12K or more frequently for ethanol as they are cheap and fuel is much degraded since then.

[Scotte123]

Factory is 30K, but it should be done annually/12K or more frequently for ethanol as they are cheap and fuel is much degraded since then.

I was wondering about the quality of fuel here in California. The car was running very strong at 125,000 miles on Oklahoma gas.

Will the ethanol added to the gas here cause any issues that you know of?

[Scotte123]

Replace it with OEM stock. You may have to clean your MAF sensor wires. per article at Q45.org.

What is wrong with a K&N? Never mind I jsut read the article on MAF cleaning[

QUOTE=maxnix]Replace it with OEM stock. You may have to clean your MAF sensor wires. per article at Q45.org.

You should check MAF connection also.

I had a fuel system flush done at Firestone and they said the MAF connection wasn't good so they adjusted it. I will double check.

SHAME on the dealer for letting the car's performance deteriorate like that!

.

I agree. But I don't particularly trust the dealer in Montclair. they did some work on the car and forgot to tighten the bolts on the plastic guard under the engine and then wouldn't make good on it. I was ready to pitch the car after that, but then I found this site.....

You should check MAF connection also.

SHAME on the dealer for letting the car's performance deteriorate like that! [/QUOTE]

[Q45tech]

Other issues besides destroying fuel pump, fuel lines and injectors? We are still evaluating the potential for extra ring and bearing wear that ethers and alcohols may cause.

[maxnix]

I agree. But I don't particularly trust the dealer in Montclair.

SHAME on the dealer for letting the car's performance deteriorate like that!

I wouldn't trust them either. A little note to Infiniti Customer Service might go a long way.