bucking and loseing power

[darksnyper]

Hi, I got a problem with my 97 pathfinder and have been pulling my hair out trying to figure this one out. The Pathfinder will start and run perfectly but when i drive down the road for about 10-15 minutes she starts bucking, very slightly at first but then it gets worse really fast to the point where it cant be driven. After letting it sit over night it will start just fine again but upon testing it again after replacing the spark plugs, wires and distributor cap it still does it after 10-15 minutes. Any help in this will be great.*Also replaced Fuel Filter*MAF is working fine as well

[jsm02cpa]

Sounds like it's not getting gas...

I assume it won't start up after it stalls (again, probably gas). You could pull the fuel line after it stalls and see if the gas is pumping out. Could be the fuel pump has a problem.

Anyone else had this happen to them??

[darksnyper]

Sorry it will start back up, Fires right back up no problems but then it runs like complete garbage the RPM gauge will jump around randomly anywhere from 300-1100 RPMs till it dies again also i forgot to mention that when the problem starts when going down the road the RPM gauge will start jumping around as well jumping as soon as i get the surges about 1000 RPMs, it starts out very slight then over the next 3-4 minutes it becomes really heavy and just becomes undrivible.

[oasisx]

did you ever replace the spark plugs? if so make sure they're the right step plugs. colder or hotter plugs could cause misfires and it would create at "bucking" feeling while cruising

[darksnyper]

The spark plugs are all right gap is set to .44 which is correct as well it seems to start doing it when entering closed loop so im suspecting its a sensor. I checked the EGR valve for giggles just to make sure it was not gummed up or anything and it checked out fine too.

[darksnyper]

I had an idea on this and thought maybe its the one of the O2 sensor's if you think about it it makes sense b/c it only happens after 10-15 minutes meaning it works fine in open loop mode running and maybe after 15 minutes just about the time that closed loop kicks in it feels as if its choking as if a bad o2 sensor could be telling the ECU its running lean dump gas any ideas on this theory?

[oasisx]

to test ur closed/open loop theory, i believe u could test it by doing a WOT run, not sure about these cars but on most, including my old one(a toyota) when the throttle body reaches a certain position i.e WOT, the system switches from closed loop back to open loop.

[darksnyper]

So its not any of the o2 sensors i unplugged them all to get it to stay in open loop and yet again after 15-20 minutes the gremlin came skulking back out, im really racking my brain trying to figure this one out.

[darksnyper]

well after this long it is still doing it( been driving around my other car for now) i replaced the fuel pump on a whim but same deal still there is also a thumping noise coming from the exhaust. Any ideas?

[Chuck Tribolet]

I'm thinking an electrical problem that happens when the electronics get hot.

I don't think it's a fuel supply problem, that tends to be independent of temperature.

Does it take longer to start on a cold day?

[Chuck Tribolet]

And is it throwing any codes? If it's running that bad it sure should.

Is the SES on? Does the SES light work (it should come on for a few secondsafter you turn the ignition on).

[darksnyper]

The SES light does work yes but its not throwing any codes it almost sounds like a misfire but I am not to sure, bad coil? maybe idk short idk

[darksnyper]

Well just to not leave anyone hanging who's watching this post or maybe having the same issue, I took it into the shop and at first glance he thought it might have been a fuel injector but i told them to just run the tests and left it over night. He called me and told me it was my Distributor go figure i had a hunch since i had checked all the fuel related problems it might have been that spark would have been my next step but i was tired of guessing I am having them put a new one in now and ill be picking it up tomorrow $140 for the labor and $375 for the parts that is money well spent, but im just glad this is solved. Thank you for everyone's input on this.

[REZN]

i believe im having a similar problem.when i start my car for the first time of the day it will start fine but after about 5 seconds the rpm drops to almost 0 and if i tap the gas it just shoots up and when it comes down it sometimes hits 0 and shuts off on me.so i always turn the car on and leave it on for abt 5 min then drive it. but also i feel as if the car is heavy.. like it doesnt have the power to drive. my friend who knows cars very well said it was the fuel pump. the guy at autozone said its probably 02 sensors since my ses light was on and the code it threw out said it was the sensors. idk what to dohow much was the fuel pump?

[darksnyper]

The fuel pump and strainer ran me about $130 but putting it in myself was a real pain in the a** b/c of a lock on the bottom of the fuel pump assembly, any way on the topic of it just shutting off then come back up after pressing the gas i would have a look at your Throttle positioning sensor or crankshaft sensor first, you can also test your fuel pressure to make sure its running right but like i said b4 it can get very pricey just guessing and replacing parts, if you do decide to replace the fuel pump gimme a shout ill tell ya about the lock on the fuel pump that took me 2 hours to find.

[REZN]

thanks. and it seems as if my overdrive doesnt kick in.i can easily cruise out of red lights and merges etc... but when i hit the gas too hard my rpms just shoot up and my mph stays the same. if i keep the car under 3 rpm im ok.. idk how to explain it lolbest way is to say im merging onto the highway. im going up the ramp at lets say 35 and highway is doing 70. for me to get to there speed i have to speed up slowly. i cant just floor it because my car just wont go anywhere and it will just stay on the same gear. i use to be able to hit the brakes and gas and start burning out. now it doesnt. its as iff my car lost alot of its power.

[kevd123]

Thank you for you post and all of the information. I'm having a similar problem with my 97 Pathfinder. Lots of random bucking and an occasional stall. It starts right back up. I thought it might be a fuel/air problem b/c I live in Guanacaste Costa Rica and the air has been very dusty the past several months. I changed the air filter and fuel filter and put some fuel injector cleaner in my tank but I'm still having the issue and on top of it, the vehicle is overheating now. It seems to run fine for a bit and I don't see the symptoms of a blown head gasket so I'm wondering if it might be the distributor as well. It only oveheats going up steep hills. I'm going to have the spark plugs and thermostat replaced as this weekend but I'm not confident that will solve the problem. Has your 97 pathfinder been fine since you had the new distributor put in? My PF is has a manual transmission so I know it's not a transmission issue causing the bucking. I want to be sure that I narrow down the issue as much as possible otherwise I could end up spending as much in the shop as I would buying a new vehicle! Thanks again for you post... Pura vida!