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‘98 Nissan stalling when coming to a stop

Maintenance/Repairs
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#1

Before I begin, let me make it clear that I’m a newbie when it comes to working on cars.

So, my ‘98 Pathfinder has about 210,000 miles on the odometer, and I haven’t had it for very long.

I’ve had an issue with the car stalling every time I come to a stop too hard. The car will shudder when I brake and to prevent it from stalling I have to let off of the brake and ease back onto it (keep in mind this is only when I come to a complete stop). If it stalls, I have to turn the car off and turn it back on again. I’m also having issues with acceleration, it seems to have a rough time switching gears (automatic transmission) and if I need to accelerate quickly, like getting on the freeway, I also have to let off of the gas and reapply pressure to the pedal. Not sure exactly how to explain this but the car jerks as I press down on the gas pedal a second time. It’s usually slow to accelerate, sometimes my acceleration/the stalling isn’t bad and sometimes it’s really bad. This are essentially the only symptoms.

Check engine light comes on and off, I have 2 recurring codes. One is for a bad knock sensor and the other is the my evap canister.

I have several theories and things I have already tried.

I have replaced the fuel filter, done oil changes as normal, used Lucas transmission fix with my transmission fluid as well as Lucas fuel treatment in my tank. The Lucas transmission fix seemed to have helped for a maybe a week before the engine light came back on; not sure if this was just a pseudo effect, if it just happened to be one of those periods where my car runs smoother like i mentioned, or if it actually helped somehow. Regardless, problem is still there.

I have pondered if it’s the fuel pump, needs a transmission fluid change, new transmission filter, new evap canister (although the symptoms I’ve looked up for this don’t match up even remotely, car only has trouble with acceleration and braking), and now I’m wondering if it could be as simple as an air filter. The symptoms of a clogged air filter have matched up the most with my cars issues.

No transmission leak as far as I can tell, fluid level is fine; but I’m not a mechanic.

This car has not been well maintained or serviced as it should have been, I’m sure that most of the things I’ve listed need to be done regardless. The stalling is my immediate concern.

Thanks for reading, if anyone has any ideas please let me know!

#2

I would simply do a complete tune up…which is not that involved on a 98’ Pathfinder. Change the spark plugs, distributor cap and rotor and even the wires with that many miles on the clock. Change the engine oil (w oil filter of course) and the air filter also.

Pay close attention to the air filter box and all of its connections…like the large black rubber hoses that connect the filter to the intake…look for any cracks or leaks. None of these black hoses or tubes can have any cracks or anything causing air leaks. Remove the MAF sensor and spray it off with brake clean spray or starting fluid…or aerosol MAF cleaner (the others will suffice just fine however). This will clear off any kind of residue or dust or worse from the MAF element so that it can measure Air more accurately (which is very important for fueling).

Without a full and proper tune up… there is no reason to look elsewhere or have anyone here suggest what to do because no one including you know when the last full tune up had been completed…and its vital to how the engine runs. Once you do everything outlined here we can then move on to engine ignition timing and the Air Idle Control Valve if need be.

But you need to do the full tune up first just so you and we know the state of “tune” and maintenance at this point…it may be the only thing you need. We can move on from there if no change was made but I would be a bit shocked to hear that no engine running improvements were made by the tune up.

#3

There may be a problem with Idle Air Control valve.

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Tester

#4

Thank you so much! I’m gonna get started on everything tomorrow morning and get back to you guys with the results.

#5

I also tend to think Idle Air Valve but a vacuum leak is also a possibility. You might check the hose connected to the PCV valve as that can create a fairly large leak if split or hardened with age and not sealing correctly at the fittings.

#6

I would say first and foremost maintenance is key. Check over the car for vacuum leaks, spark plugs and wires, filters, and overall condition of the intake. Second shift into neutral when decelerating and see if it still happens. If not it’s likely a transmission problem but feel free to keep reading as it’s all valuable information.

Honestly the easiest way to determine if something is wrong with the engines operation is with a cheap OBD to usb device and a laptop if you already have one. They also have them for your phone that work over bluetooth. Maks sure you get one that has live data output and isnt just a trouble code reader. You can forgo a lot of pointless testing with one of these and some insight into how it all works together.

Once the obvious surface stuff is taken care of check your fuel trims and make sure your O2 sensors are ocelating properly. Make sure your throttle position sensor is reading correctly as that is used by the TCU to control what gear it goes into and how long it stays there when you are really getting on the throttle. Sometimes they go bad. Sometimes they just need to be clocked back into position.

It probably isnt an issue but just to be sure you may want to pay attention to engine RPM as interpreted by the ECU when the car is plugged in. Specifically if there is interference in the signal that could be causing the ECU and transmission computer to think the engine speed is higher than it actually is. The tachometer often isnt as sensitive to certain types of interference as these components so seeing what the ECU thinks is going on can give you some indication of something is wrong. You would be looking for 400rpm difference or more between the ECU and tachometer as it’s not uncommon for the tach to be off by 1-200rpm or so.

If engine operation looks good I would next look at the transmission. Particularly if yours has a lock up clutch that may be sticking due to a gunked up valve body or buildup in the lock up clutch assembly itself. That could cause stalling and make shifting in general hard on the transmission.

Again all of this is just the possibilities. It’s hard to tell until you procedurally sort out what it can’t be. Process of elimination starting with a good running well maintained engine.