Q45 Rough Runner

[akrq45]

Have a problem with a not always rough running Q45. I get bucking, jerking, "sponge pedal" (feels like the car is boging down), and some rough idling. It has stumped a local and pretty trusted mechanic in part because the car does not perform this way all the time. In fact, I took it in the other day and he said that it ran great. The fuel filter was changed about 5K miles ago. Any ideas on what it might be?

[Q45tech]

ANOTHER TRUSTED MECHANIC instead of a experienced CERTIFIED INFINITI TECHNICAN with a CONSULT who sees these models on a daily basis!

One who can wave his hands over the engine and see visions of the problem and solution.

[heywier427]

q 45 tech your great all of you info is right on, but that was gay!

[superuber]

.....I must say tech, your aproach is right on but your delivery well... Welcome to NICO akrQ45!Here at NICO we are in two catagories.1) guy who relys on total dealer repair (cert. infiniti tech)2) us guys who hate the dealer (high prices) and research and study and sweat and cry and bleed until we reachQ belt status, grasshopper! (in other words we repair ourselves)

Don't go to any Joe mech. Most of them know nothing about this work of art called the Q! We may be able to help, but we need info from you.I.E. mileage, repair history, etc., etc., etc....
Modified by superuber at 10:13 PM 10/25/2006

[akrq45]

Repair History:

This has been a great car as I have owned it since '99. Mileage is 108K, Oil Changes, Tire Rotations, New Tires, Brakes, Air Filters at the normal intervals. I bought the car with 33K miles, plugs may be original hard for me to tell at this time.

[maxnix]

q 45 tech your great all of you info is right on, but that was gay!

Well, after all, it was a "pretty trusted mechanic."

[maxnix]

.... plugs may be original hard for me to tell at this time.

Then get the Infiniti dealer performed service history!

If you have had it since 33K miles and didn't change the plugs, you are way overdue. Transmission fluid exchange? PS fluid exchange? Brake fluid replacement? BG44K? Plenum cleaning? EGR and IAC valve R&R? How often are the air filters changed? How long was the previous fuel filter on?

[Alcyone]

Perhaps a bad MAF sensor? Shouldn't be plugs unless it's misfiring.

[pito11213]

If you haven't changed the plugs all this time then what else haven't you changed?

Sounds like you need a full tune up. Clean maf, clean throttle body. Just some of the basics.

[bullittandy]

Another "warm" welcome to he newest member of the site.

[Jesda]

ANOTHER TRUSTED MECHANIC instead of a experienced CERTIFIED INFINITI TECHNICAN with a CONSULT who sees these models on a daily basis!

One who can wave his hands over the engine and see visions of the problem and solution.

+1

[96Qowner]

To answer your question, it sounds a lot like a misbehaving MAF. Try cleaning it according to these instructions:

http://www.q45.org/maf.html

It's cheap and easy. The MAF connector and the MAF itself is a common problem on this series Q45. Use the forum's search function to find loads of threads on the subject.

[akrq45]

I appreciate the reponse.

I cleaned the MAF, following the information that you provided. Unfortunately, I did not experience an improvement in how the car runs. I also unplugged the MAF and started the car to see if it ran any different. It ran much, much worse. An assumption, perhaps incorrect on my part, is that the MAF is functioning correctly, given that when I plugged the sensor back in, the performance did improve. Any idea whether that is a valid assumption or if I should consider another possible approach??

[Q45tech]

When you unplug the MAF connector examine for signs of corrosion, same with the CAS connector.

The problem most non dealer techs have is the lack of a year specific FSM.

The whole mechanic vs technican debate can be eased with a technican who is familar with Nissan as most of the systems are very very similar.Nissan specialty shops almost always have a Consult.

The MAF, the fuel system, the CAS, the IAC..........the coil on plugs is usually somewhat different but even US cars are adapting it know.

The real distinction is usually between those that have a 2 year Associate in Automotive Technology Degree or are ASE Certified vs a self taught mechanic

[96Qowner]

I see yours is a 97 and therefore OBDII. Hasn't it thrown a code? Odd. Since it's been misbehaving recently, there should be codes stored.

But, yeah, it does sound like your MAF is ok - so, on to another approach. It's a fairly severe symptom, so it points to a failure of a connector or sensor. Was it running smoothly or poorly before you unplugged the MAF?

[elwesso]

akr- im located in Anderson, will be around this weekend if you want to meet up and ill be glad to take a look at it and see what we think is going on!!!!

EDIT: It could be fuel pressure related.... have you replaced a fuel filter or anything???

[akrq45]

elwesso

Thank you for your kind offer to meet up. Perhaps Sunday might work this weekend, or we can look at other times as well.

To answer your question, the fuel filter was replaced this past summer.