hesitation 94 q45

[eric8859]

My 94 q45 with 102000 miles gets a occasional hesitation at about 40mph where the vehicle sort of jumps reagrdless of whether or not the gas pedal is pushed, when you leave off of pedal it coasts back to speed, only happens occasionaly but when it does you really cant go over 40mph, vehicle even dies, have changed fuel filter, no codes are showing. Any ideas before going to dealer! Thanks eric

[DougQ45]

Mass Air Flow Sensor ("MAF") It is the little black box with an electrical wire attached to it and it on top of your air cleaner box. DO a search on this subject and you will find a wealth of information.

[eric8859]

will be cleaning MAp in next couple of days, thanks for the info.

[elwesso]

I agree wiht that...

I see your in chicago, check in at this thread!!

http://www.nissaninfiniticlub....79411

[eric8859]

Well cleaning the MAF did not do it. Still getting occasional bucking. Do you think the MAP needs replacing, if so, is there a way to check before investing?

[maxnix]

Are you in third or drive?

Cannot be in drive at such a low rpm without bucking unless the engine is in perfect as new state of tune. Not good for it even then.

[Jesda]

I have a similar problem, and am currently in the process of getting my fuel filter replaced and my battery replaced. I also need to have the alternator checked or replaced (its used, installed 2001).

I found that cleaning the MAF -and- throttle body made a tremendous difference in reducing that "bucking". But the hesitation and bucking is still there on occasion. When I turn some electronics off on the highway (AC, headlights) it goes away entirely. This leads me to believe the battery is not properly holding a charge, because of the battery itself or a bad alternator.Replacing my negative battery terminal I think helped as well -- another indication of electrical issues.

So here's my checklist:1. MAF - Done for $3 - Big help. More power.2. TB - Done for $2.50 - Big help. Much better idle.3. Fuel Filter - $134. Battery and Terminals - $805. Alternator - Will purchase one used for $55, because with school eating into work hours, I'm broke.

-Jesda

[eric8859]

does it in both 3rd and drive, already changes fuel filter and battery is new, car still bucks occasionally during day even when no electronics are on, may have to break down and try new MAF and/or dealer checkup

[Jesda]

Does anyone know if bad knock sensors can cause this? Or maybe transmission fluid due for a flush?

[elwesso]

1. Does anyone know if bad knock sensors can cause this? 2. Or maybe transmission fluid due for a flush?

1. Maybe, especially if its with other things like dirty intake and stuf like that.....

2. No

[eric8859]

put in new MAF, all seems well, except for humming fuel pump, I noticed some time ago there was a thread with pictures on replacing fuel pump in q 45 (mine is a 94) can anyone send me same or post again? After reading links to such, replacing it sure seems to be the right thing to do. Thanks

[MR.Q]

It could be your Crank Angle Sensor on the driver side. It says NISSAN on it.

[qship96]

scarey

[squeefoo]

Search for adjusting the AAC, cleaning the Throttle Body (TB), setting the ignition timing. For a very impressive resource and how to pages go to : http://www.q45.org