# Slight hesitation/shutter coming out of low speeds/coasting



## jef46614 (Aug 9, 2006)

Hi, my car is hesitating/jerking momentarily after i coast for awhile in low speeds. like for instance i live on a curvy street that is marked at 20mph. often i have to slow down and speed up because of children, other cars. etc... so when i let off of the gas or push the gas pedal after coasting at low speeds i get this shutter or jerkiness and then it runs fine. my car starts and runs fine. it doesn't hesitate when i give it a lot of gas. i don't notice this shuttering at highway speeds, only at low speeds. no check engine lights. I do have a couple of mods though.... air intake, header, exhaust.... none of these problems occured anytime close to a modification. I mention the mods because i wondered if they could cause a sensor or something to go out faster. I suspect the MAF... but i have never dealt with a bad MAF before so any comments, suggestions would be greatly appreciated.
THanks!
Joel


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## jef46614 (Aug 9, 2006)

Also... It's been doing this for a few months and progressively gotten worse over that time span. before it started jerking i did get a knock sensor code. cleared it and hasn't came back since. Figured it was bad gas or something. i tried injector cleaner a few times with no luck. All tune up parts have been replaced with in the last year. Was possibly thinking it could be the fuel filter. i havne't replaced that in about 50,000... but i don't think the symptoms add up to that. Anyway, please help. Thanks!


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## MickeyKnox (Jun 17, 2006)

it may be knock sensor.

they talk about knock sensor function here. and how to test it the old way.
very useful read in general and also relates to your problem.
http://www.federal-mogul.com/fmeconnect/technicalservices/downloads/1422.pdf

I am pretty sure it's knock sensor.
procedure they desribe there is to tap the engine at the place near knock sensor.
your rpm should go down lightly. 

best way is for you to buy Hayness manual or use this more detailed manual
http://www.phatg20.net/modules.php?name=Downloads&d_op=viewdownload&cid=69
and test your knock sensor's resistance and maybe there are otherways to test it.


maybe it's not knock sensor(which is expensive).


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## LONDONDERRY (May 19, 2004)

jef46614 said:


> Also... It's been doing this for a few months and progressively gotten worse over that time span. before it started jerking i did get a knock sensor code. cleared it and hasn't came back since. Figured it was bad gas or something. i tried injector cleaner a few times with no luck. All tune up parts have been replaced with in the last year. Was possibly thinking it could be the fuel filter. i havne't replaced that in about 50,000... but i don't think the symptoms add up to that. Anyway, please help. Thanks!



HAve the computer scanned regardless, there might be a stored code. It sound slike it either you MAF sensor out of wack and need adjustment or replacment or you are experiencing a intake mnifold gasket leak.


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## jef46614 (Aug 9, 2006)

Check engine light is now on........ will scan it this week to check the code. What's the best product to use for cleaning a MAF? I'm going to go ahead and clean that out regardless of what the scan turns up. THanks!


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## LONDONDERRY (May 19, 2004)

Get the code first before you do anything. You might be chasing the wrong problem by cleaning the MAF which might not need it.


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## jef46614 (Aug 9, 2006)

Ok, the codes are...... P0325 which is a knock sensor malfunction........ and P1491 which i couldn't find ANYTHING on. does anyone know the second code?? thanks
Also, has anyone changed a knock sensor before? i know it's on the back of the block. I was just wondering how hard it was to get to. I have a haynes book on the car so i could look in there but the pics aren't always the best.


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## MickeyKnox (Jun 17, 2006)

http://www.nissanforums.com/general.../124306-all-trouble-codes-hayness-manual.html

all trouble codes.
your 1491 is vacuum cut valve bypass valve. I don't know how to fix it or what caused it.


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## jef46614 (Aug 9, 2006)

Hey, i fixed the problem...... i bought a scion Tc


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## LONDONDERRY (May 19, 2004)

jef46614 said:


> Hey, i fixed the problem...... i bought a scion Tc




Went over to the dark side?

not a good fix


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