92 not so smooth

[BadQ45t]

I'm finally driving around my old mans 92' Q45 and I've got a few questions. First, at idle it isn't very smooth...I know it isn't suppose to be as quiet and smooth as my Lexus-ified 97' but it seems to shake the car some. Is this normal for idle.

Also, I was expecting some type of neck snapping performance and I'm pretty sure my 97' is faster. What are the first things I need to do to get the performance up to snuff. It is a 92' with 93k on the odo, he's done all the suspension stuff except the shocks (I'll do these as soon as I get the pinks slip). Are there motor mounts that get old? I've seen posts about Pleum cleaning, is that where I'm losing the power?

Also, anybody know where I can get reasonable mats, his are shot and the dealership in my town didn't have them.

Thanks in advance,

Jeff

[PalmerWMD]

Jeff

-Anything but a perfectly smooth idle is not normal virtually regardless of milage.-Your 92 should be noticably stronger than your 97.Most common cause for low power dirty TB (I was educated about this by Dennis aka Q45tech in Atlanta).Other causes MAF , or more commonly MAF connectors, out of spec injectors will also lower performance and are also a known contributor to bad idle (as is dirty TB).-Mats Infiniti of Lisle and Infinti of Scottdale have a great rep for good internet pricing and a discount to the members of this board.

Fred...

[AZhitman]

Sounds like an hour of tech time with the Consult is in order.

Come back with the results.

[BadQ45t]

thanks for the input, I'm not a DIY person so I'll suggest a few of these items for my mechanic to have a look. I just don't have the skills or time to worry be a DIYer.

I assume MAF is Mass Air Flow?

Jeff

[PalmerWMD]

I assume MAF is Mass Air Flow?

Jeff

Yes MAss Air Flow senor.More commonly the MAF connector though that breaks sometimes misdiagnosed as the sensor

Fred...

[greg_atlanta]

Do a thorough intake cleaning, not just cleaning the throttle body. BG makes a fogger system which you stick in the intake... sprays a fine mist which cleans deep inside the plenum. Requires special equipment, dealer may have it.

When I got my '92 Q that made a HUGE difference in smoothness, power, etc.

Also do a pressure cleaning of the injectors, also a BG system requiring special equipment. I did mine recently for the first time, wasn't a huge difference since I've been using injector cleaner regularly, but did notice the car fires up faster on cold starts (WHOOSH!!).

Get a brand new OEM air filter even if current one looks OK (about $10 from Scottsdale, dealer may markup a lot).

And finally.... try to find some BG MOA (or "111") oil additive. I've been using half a can each oil change, big difference in smoothness, esp. at higher rpms.

That's a start. Enjoy!

[greg_atlanta]

Go ahead and change the coolant too. Use distilled water and either Nissan AF (kelly green, not neon green) or Havoline Orange AF.

Best to flush with distilled water until it runs clear then add AF. Mechanic may not have patience to do that, if you want to DIY we can advise how (it's one of the few things I DIY).

Oh.... and next time, switch to Mobil 1 ATF in the trans!!!

[BadQ45t]

Thanks, looks like I get the joys of caring for a ten year old Luxo now! My 97 may be so as fast, but I haven't had to do alot to it! Well given my 265k 85' maxima and my 160k 84' 300ZX I guess we'll just add this the garage....

I'm going to see about the plenum cleaning and get the radiator flushed when I have a 90k service done at Cars 101 when I get the car at the end of the month. Thanks for the suggestions, if I'm going to be dealing with this **** I at least want that neck-snapping speed you boys are always talking about!

[greg_atlanta]

I at least want that neck-snapping speed you boys are always talking about!

It's there.... waiting to be uncorked.

:yummy

Mine keeps getting faster and faster... just need some more breaking in.

[Q45tech]

A 123k 93Q came in from Virginia very very very bad idle, [smothed out a little above 2500 rpm. A local dealer in ATL changed a coil [common I30 problem], another ATL dealer changed an injector [easiest one to get to], when we measured all the injectors, 3 more were out of spec [16,22,33] plus the bad thermostat wouldn't let the car warm up above 159F. PLus the usual dirty plenum/TB hadn't had a 120k service yet ....plugs

How did the dealers do a power balance or any diagnostic without correcting the warm up ????? not as many current techs are familiar with old Q but the Consult warns you and won't proceed till the 176F is reached???????

The other clue was the injector bank trim going above 120%[130%] and the O2 staying lean on acceleration!

Guess they see too many new ones with OBD2 which spells out everything and the 90-95 require too much thinking and hand testing! Took us about 15-20 minutes to come to the above conclusion.

Another Ode to Oxygenated Fuel!

[greg_atlanta]

Another Ode to Oxygenated Fuel!

Is Virginia gas oxygenated? Or just DC area?

[BadQ45t]

Wow, sounds like I need to leave this at my mechanic for awhile once it is fully mine (still waiting for Dad's divorce before Daelaus does my injectors and I get the pink).

but after driving it all week, I love the car. It needs shocks too so I figure that spings and shocks for the wife's christmas present after I get the other stuff done too!