# B13: Pulsing during acceleration



## jho41 (Aug 3, 2005)

1994 Sentra XE, 198K
B13 Chassis
1.6L Engine with Air Conditioning
Manual Transmission 
4 Door 

From Edmonton, Canada

Background:
This only started to happen recently (never had this problem during last winter), and I just had my starter replaced by a mechanic. I'm not sure, if in the process of replacing the starter, he may have dislodged a part that could be causing this problem.

Problem:
Happens only during the morning, within the first 15 minutes of driving in the morning (when the engine is relatively cold). When I push the gas pedal to accelerate, the car pulses/surges. When I'm idling/starting the car seems fine. Only during acceleration does it surge. Once the car has been driven for a while (15 minutes or so), the car seems to work fine when I accelerate. Does anyone experienced this? How did you fix it?

Note, during the morning, as soon as I start the car, when I put the car in neutral and rev the engine there isn't any surging.

Other notes:
-I've added a full tank of premium gasoline before I experienced the problem. 
-Car starts without any problems
-The surging happens with a full or half a tank of gas
-I've added STP Fuel Injector cleaner in my gas tank, but that didn't fix the problem.


I've got a copy of the Haynes manual, but they suggest that it could be the fuel pump/fuel filter/fuel regulator/air intake. 

Is there any online resources out there has illustration of these parts? I'm a complete novice when it comes to car repairs. THe haynes manual does show what the regulator looks like, so I'm not sure where to begin.

To those who might know how to fix it, will the problem get worst (surging increases) or will the car just stall while I'm driving? I'm trying to get a feel of how serious this problem is.


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## ccj_drivinaround (Sep 12, 2003)

Could be any of a number of things. If it only happens during the first 15 minutes of operation, then my guess is that your oxygen sensor could have something to do with it, or perhaps some problems with your emissions control equipment. When your car is warming up, the A/F ratio is adjusted to reduce emissions, and you could be feeling a shift between a rich (lag) and lean (surge) condition. I'm no mechanic though... checkout sentra.net and se-r.net there are a lot of technical articles there on the 1.6 liter motor. Good luck !


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## znamya (Sep 21, 2004)

I would change the fuel filter as that is the cheapest option and no harm in changing anyways, the weird thing is why does it do when the car is cold, I can not find any single explanation other than what the above post says.I was gonna say the motor mount may do it but it does it not only when the car is cold. 

EDIT: by the way, did you have a chance to search this forum, the GA16DE section also, there may be valuable info there. Maybe have yoyr mechanic take a look and give you a quoto. He may have seen this problem before


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## Jaemon (Apr 16, 2004)

I had a somewhat similar problem that was remedied by replacing the fuel filter (good luck getting off the hoses), and performing a tune-up. I think the culprit was cheapo Autolite spark plugs. I replaced them with the stock NGK's and new OEM wires. I also replaced the distributor rotor and cap. Boo-ya, like new and no hesistation! Also, I've read that you should NOT use the fuel injector cleaner. It kills our fuel injectors.


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## jho41 (Aug 3, 2005)

I had the mechanic run my car through their computerized diagnostics. All the sensors were fine. He did mention to replace the spark plugs, cap and rotors. Start with that step first. 

If that doesn't improve, change the fuel filter and clean the injectors. 

I want to change the fuel filter myself. 

The haynes manual isn't very clear, but from looking under the hood, the filter is attached by a fitted bracket, after I unplug the fuse to the fuel pump, and let the engine die, disconnect the negative terminal on my battery, do I simply pull the filter out from the bracket, loosen the nuts, and pull out the hoses. Installation is the reverse?

Is there any magic trick to fitting the rubber hoses back on/off? 



Jaemon said:


> I had a somewhat similar problem that was remedied by replacing the fuel filter (good luck getting off the hoses), and performing a tune-up. I think the culprit was cheapo Autolite spark plugs. I replaced them with the stock NGK's and new OEM wires. I also replaced the distributor rotor and cap. Boo-ya, like new and no hesistation! Also, I've read that you should NOT use the fuel injector cleaner. It kills our fuel injectors.


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## Maxim (Jul 17, 2005)

jho41 said:


> I had the mechanic run my car through their computerized diagnostics. All the sensors were fine. He did mention to replace the spark plugs, cap and rotors. Start with that step first.
> 
> If that doesn't improve, change the fuel filter and clean the injectors.
> 
> ...


Nope, no magic needed, just did mine this past Wed. Unscrew the hose clamps, pull off the hoses (might have to twist them a bit) reinstall is the reverse (least I did it that way). No problems.


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