periodic sluggish 96Q

[alexander]

What might cause my 96Q to be super fast some days and other times, sometimes the same day, really struggle of the hills of San Francisco.

New MAF,AAC Valve, fuel filter,OEM plugs, O2 sensors, OK knock sensors, all within the last 4 months. 135k miles

Infiniti Service rep seems to be at a loss for suggestions.Should I just give the car to the Senior tech for a week and let him drive it to experience the lagging acceleration or give up?Any other ideas?

Alexander

[maxnix]

Really check the MAF connector wiring, and if that is not flakey, look at the solder of the wiring in the box leading to the hot wires.

How does the ATF look and smell?
Modified by maxnix at 5:40 AM 10/29/2008

[alexander]

ATF is fine.Had the full flush about a year ago.since Infiniti replaced the MAF three months ago, wouldn't a problem with the wiring been been inspected then? Then again it looks like I have to point out everything to them to get items repaired. They don't seem to spend a lot of time with the car, just what is obvious.

[Q45tech]

Define super fast with a stopwatchand temperature readings as 96 are real slugs compared to previous years............the cam changes to drop VVT caused a serious torque deficit especially until 4500 rpm.

Have fuel pressure measured under driving conditions [gauge taped to windshield] make sure you WOT at 44 psi.

[maxnix]

OK, sorry I didn't remember. That's why mechanical problems are best posted in IOM with a recent maintenance history.

If it is indeed periodically sluggish as opposed to being constantly sluggish, then a competenet diagnosis is indicated.

Other than going to http://www.jerrytucker.net for a once over, I have no clue how to find a competent Senior Infiniti Technician in the Bay area.

On a side note, I would be curious to the depreciation on a Maybach 57 and wonder if any thought given to replacing it with a President converted to LHD?

[goody90q45]

.......New MAF,AAC Valve, fuel filter,OEM plugs, O2 sensors, OK knock sensors, all within the last 4 months. 135k miles.........Alexander

I read through a couple of your old posts on the same subject and nowhere do I see mention of replacing the fuel pump or fuel pump control unit (FPCU).

It's been suggested by 3 or 4 posters that you measure fuel pressure and BadQ45T has recommended a couple of good shops in the south SF area that he uses. I too would suggest that you get away from the stealerships and use one of these shops. If that's not possible, and with your Q at 134k miles, I'd suggest dropping another $1000 and tell the stealership to install a new fuel pump and FPCU.

[alexander]

Fuel pressure was tested pressure at idle was 34 PSI 44 pSI MO

OK not super fast, just noticably quicker at times.

There is a Senior Tech in Concord CA at that will be the guy I give the car to.

[qship96]

Fuel pressure was tested pressure at idle was 34 PSI 44 pSI MO

OK not super fast, just noticably quicker at times.

There is a Senior Tech in Concord CA at that will be the guy I give the car to.

No, it IS superfast, as the quickest time ever recorded on this site for a STOCK 90-96Q was done in a 1996Q...search old posts by rsiwicki for the track timeslips....that being said, NO stock 90-96Q is "fast" by todays standards.....similar to todays jap v6 family sedans, at best.

Have you checked codes with a code-reader, I am wondering if you are experiencing an intermittant knock sensor{or its harness} failure-this would NOT illuminate the "check engine" light.

[goody90q45]

fuel pressure was tested pressure at idle was 34 PSI 44 pSI MO.....

Since your problem is intermittent the fuel pressure may have been checked when everything was working.

No CEL or codes (except KS) = bad Fuel pump / FPCU

[alexander]

Maxnix, I found a senior Infiniti Tech at Nielleo Infiniti in Concord CA. He's been there since 1991.

The husband sold the Maybach in August at the Pebble Beach Concourse d' Elegence to someone crazy enough to give over 50% of the original price.Thank God we didn't wait until next years show, if there will be one.Great interior, ugly car.

[maxnix]

I do like that depreciation schedule! Thought it was the wife's car?

Senior Infiniti Technician means he was trained on it in 1989 when the G50 was introduced. He should sort it out then. Leave it with him for a week.

[alexander]

Senior tech at Niello Infiniti said he would be happy to drive it for awhile.After getting the new MAF etc. mileage went up to 22mpg highway, and now it's back down to 15mpg. So something is going on.

Should have used " " when using the wife "word", Now that we're legal I can use the correct term. I still call the Q "she".

[maxnix]

Never thought of the Maybach as ugly, just a little overwrought.

[alexander]

Took the 96 Q in today with the same performance problems and they finally found a code for the knock sensors.The Senior Tech at Niello Infiniti did a long test drive and the car finally lost power and the code came up.about 2 grand for the work. Sounds right?What else can they perform while they are 'in there'?

[maxnix]

I would replace all the hoses also if you are keeping the car an other 2 or 3 years for sure. Lots of posts about the under plenum hose job. I would hate to pay dealer price for parts and labor, though. You will avoid a lot of repeat labor, so I would say $3K a t their price for all hoses and gaskets, cleaning TB, IAC adn EGR valve, lower runners adn plenum. If they balk, take it to

http://www.jerrytucker.net

And spend a few days.

The KS subharness must be replaced.

[qship96]

Took the 96 Q in today with the same performance problems and they finally found a code for the knock sensors.The Senior Tech at Niello Infiniti did a long test drive and the car finally lost power and the code came up.about 2 grand for the work. Sounds right?What else can they perform while they are 'in there'?

They should have been able to determine that issue a long, long time ago for you if they were looking for stored codes each and every time you brought the car to them complaining of sluggish acceleration issues......once the code is triggered in the computer, it remains there for quite some time after it no longer determines there is a problem{IF the knock sensors were intermittantly functioning} and if the knockers were faulty without being intermittant, the code stays forever until fixed.

Sloppy technicians and diagnostic methods.....especially for such a common issue with the Q, and every other nissan product{the most common code stored on all nissan cars due to crappy knock sensor design}would lead me elsewhere,like to Jerry Tuckers in a heartbeat

[alexander]

When I went to the service department to pick up the Q, I questioned if these codes for the knock sensors were recorded and stored previously with all my other complaints.(the last 2 years).I could tell he did not want to point to other Infiniti's service departments not catching the problem even though the data is stored.If I told them it was an independent service company, they just might have said 'they' f.. uped 'next time come to us'.So this problem will go to the guy in San Mateo who is highly recommended.

[pirenuri2]

Alexander,Were you able to resolve the issue? I am having the same problem with my 98 Q. It runs fine about 20 minutes then it becomes very sluggish.

Thanks

[maxnix]

Yes.

He starts a new thread when there is a solution and besides the solution, usually posts a new problem also.

Keeps his threads a little less than cohesive.