love my 94 q but love it more now....

[SUITE E]

I have been having vibration problems which I thought to be the driveshaft or maybe an injector. I had it at 2000 rpm and I never had as much power as i thought I should. Plus it usually began stumbling and running rich until I clean the MAF connector to the point I would extract the wires under a magnifying glass to clean and close the gap to get a better grip on the male contact. That helped a bit but never lost the vibration. Last week though I was overheating. I had my clogged radiator replaced. My mechanic (a nice Japanese guy at Tokyo Automotive in Anaheim) did the work and when I picked it up he told me the vibration is GONE. He doesn't know what he did and did not charge me for it but I guess he must have unplugged and replugged in a faulty connection without knowing it. Well driving back to work was a joy I can tell you. Running up past 2000 rpm without a shudder felt great. I recleaned the MAF contacts. disconnected the battery (hoping maybe something will reset, but it probably had no effect) and now the car idles factory fresh smooth and goes like stink. My question after this happy diatribe is this. What in the experience of the masters here (I am not being flippant BTW) could have caused the improvement in the running of my engine? What did my mechanic unknowingly do when replacing the radiator? I ask because I know these happy driving moments will not last, and something will soon corrode giving bad signals to my engine and my bad vibes will return. I would like to get in there and clean em up real good.Thanks for your answers.

[blurama]

My Q45 exhibits the exact conditions you describe. I would welcome the solution.

[maxnix]

It is really difficult to even guess what causes a particular symptom without a maintenance history. Most owners neglect or postpone preventative maintenance, which is still neglect. The necessary regimen to restore and maintain a G50 to OEM as new specifications can be found in the previous posts, especially the posts by Q45tech, which are mandatory reading. All of them. From the beginning. Each one. Am I clear?

Very seldom does a properly maintained Q45 exhibit weird symptoms. When it is maintained, it is much easier to isolate the likely probable causes.

[elwesso]

thats very interesting... I know of a couple Q45s that are experiences what you say... Possibly a CAS conection? Maybe it was running hot and retarding timing big time.. Plus knocking......

[SUITE E]

Thanks, yes there was a slight knocking which caught my ear. And then the needle started a climb. I pulled over and had it towed. Don't need to add head gaskets to the bill by trying to "MAKE IT A LITTLE FARTHER LOL". But the underpower had been with me since I bought it 6 months ago and did not go away until the radiator replacement. So not having spent much time getting familair with all the sensors and electronics and their many locations, I thought maybe somebody might know if there was any connector that would have been touched during the course of the Rad. R&R.BTW to the post before, maintainence is important I know. I have poured money into this trying to make up for the lack of it from previous owner(s). Dam things are like boats (holes in water that you throw money into) but I cannot take a boat to work everyday. I have had many cars and this is my favorite. I began to customize the interior which Freud would say means I intend to keep it

[PalmerWMD]

I dont know about the virbration but underpower can be easily explained by high temps due to weak radiator , going a tad above the spec value F, may still induce the car to retard timing (=less power)

As for vibrations, I think you surmised correctly a sensor got dis-connected -reconnected and/or bumped during the process and is sending better signals now.

Fred..

[blurama]

The 1994 Q45 that I purchased came without history and documentation as well. It was a one owner, very clean with limited wear, and had just 68,000 miles. On its' first visit to the Infiniti dealer (after the purchase) it came away with a new water pump, knock sensors (and all the hoses, etc) and value cover gaskets.

At the moment the one symptom it seems to have is the shudder or vibration upon initial acceleration at about 2,000 rpm.

Other than that it is about as smooth and powerful as I remember the 95 that I had purchased, new, years ago. I intend to continue the care and feeding to bring it up to OEM.

[PoorManQ45]

At the moment the one symptom it seems to have is the shudder or vibration upon initial acceleration at about 2,000 rpm.

My Q45 has that same problem sometimes.

It's very confusing to figure out what is the cause of the problem. It doesn't show up everytime you accelerate. It seems random.

[maxnix]

The 1994 Q45 that I purchased came without history and documentation as well.

All Infiniti cars have an Infiniti dealer performed service history. All the owner has to do is request it.

Sound like a great find, but I am perplexed by your problem.

Oh, California! Have you ohmed your injectors? Performed a BG injector flush? How often has the fuel filter been changed? Any humming from behind the back seat before you engage the starter?

What clogged the radiator?

[SUITE E]

All Infiniti cars have an Infiniti dealer performed service history. All the owner has to do is request it.

Sound like a great find, but I am perplexed by your problem.

Oh, California! Have you ohmed your injectors? Performed a BG injector flush? How often has the fuel filter been changed? Any humming from behind the back seat before you engage the starter?

What clogged the radiator?

yes but I have not requested it yet. I will ohm my injectors myself one day, but now it feels like all eight are kicking ***. Fule filter has not yet been changed by me. and yes I hear my fuel pump buzzing away which means I should have one on hand for the day it fails.

[DAEDALUS]

The pump will draw more and more current as it ages. At some point the current draw could cause a failure in the pump controller--really not uncommon. As expensive as the pump is, the controller costs even more.

[maxnix]

yes but I have not requested it yet. I will ohm my injectors myself one day, but now it feels like all eight are kicking ***. Fule filter has not yet been changed by me. and yes I hear my fuel pump buzzing away which means I should have one on hand for the day it fails.

I think you really need to do some reading.

[Jesda]

Im curious about what causes the 2000 rpm vibration as well, but I'm going to do the O2, KS, and plenum all at once. That may or may not resolve the problem, but its all due anyway. And I know my motor mounts are worn.

[blurama]

The vibration (shudder) at initial acceleration (2,000 rpm) is consistent. It occurs under "load", i.e. it will not be obvious when starting off on level ground or down a grade, only up a hill, or even up a slight grade.

I was also thinking that it could be a driveshaft or injector. (The injectors tested fine.)

If this were a sensor, how would the sensor be identified ? Would the Consult aid in this ?

[maxnix]

The vibration (shudder) at initial acceleration (2,000 rpm) is consistent. It occurs under "load", i.e. it will not be obvious when starting off on level ground or down a grade, only up a hill, or even up a slight grade.

In D? Not a good idea to be accelerating up a grade at only 2K rpm in D.

How clean is your intake path, MAF, EGR and IAC valves?

[SUITE E]

My vibration is still there even though the engine runs very well. I know my car has had an impact during its life before my ownership. I am guessing here so tell me if this makes sense. The motor mounts, I believe could have been broken or damaged during whatever collision happened. They certainly would not be on anyones mind when writing up the damage estimate and they are not exactly a part requiring periodic replacement. If they are damaged I could be feeling the effects of undesirable contact. Although this engine revs smoothly, everything has a natural frequency. Like a tuning fork. 6 bangers run turbine smooth because they are naturally well balanced. 8's don't no matter what you do. There are uneven firing pulses and so on. So our 8 has a bunch of ways to shake, at different times. I just think my motor is sitting on something harder than it is supposed to. I can feel it in the seat of my pants. Thoughts?

[SUITE E]

BTW if you don't mind me asking, and the manual has nothing about it that I have seen yet, what is the CAS.

[PoorManQ45]

Hopefully your Q was not in a rear end collision. If that were the case, then you could almost immediately pinpoint the extraneous vibration to the drivetrain.

A worn or broken motor and/or transmission mount is a possibility. You will get odd/weird vibrations when one or more of the mounts are worn or broken.

[DAEDALUS]

BTW if you don't mind me asking, and the manual has nothing about it that I have seen yet, what is the CAS.

Crank Angle Sensor--Tell the ECU where the crankshaft is (based on where the exhaust camshaft is).

[SUITE E]

Day-am that's a clean intake. Same for the rest of the bay too. And thanks for the answer. The collision was in the right front.

[Jesda]

*bump*

Hope you find a solution soon. Ive been trying very hard to determine exactly when mine occurs. I *think* it happens more while climbing uphill or from a dead stop. Sometimes its not there at all, and for the life of me I cant figure out why.

-Jesda

[SUITE E]

After ohming my injectors, I found number 7 open. That is the miss causing a vibration. Will check into the wiring to it in a day or so.. Weird being completely open so maybe it is just a bad connection. The other thing I am learning is taking the connectors apart after they have been together so long, opens up a Pandora's box. They never sit right again without cleaning the contacts very well. It almost makes me want to solder the connectors together and wire in a new American made waterproof connector downline.

[Jesda]

Ahhh! Makes sense, since three of my injectors are out of spec. Thank you.