I've got a problem with my 98. A few weeks ago it began to develop a bucking and stutter that would coincide with the idle dropping 200 rpm. When it happens it feels like the car wants to jump, and it only does it at a stop and in gear. It's also beginning to develop a low rpm hesitation when the idle problem happens. I will feel like a miss until it gets above 2000 rpm then smooths out. After reading about it I've noticed it can be anything from a weak coil pack to a MAF to the knock sensor or wiring but I don't have the cash to simply start throwing money at the problem in the hope that it fixes it.

Also it's not throwing a CEL at all.

Any help would be appreciated.

 

scan it regardless, some codes dont turn CEL on

 

I actually experienced something similar to this when I did my rocker cover gaskets a few months back... it had almost no power below 2000-2500 RPMs and was bucking HARD after the torque converter locked up (had to turn off O/D because it was so bad that I was scared it was going to damage the transmission), had thrown no codes whatsoever when I scanned it... I got fed up trying to find a fix and just figured I'd try cleaning the cam and crank sensors gently with a soft cloth, the problem went away and hasn't come back since.

If you haven't tried cleaning the cam (1) and crank (2) sensors, I would try this first since it's a free fix and takes only a few minutes if you're handy with a socket wrench. WARNING: DO NOT CLEAN THEM WITH A MAGNET (required to state this as some people don't think about the sensors being magnetic themselves)

 

Took it to Autozone today and it came up with a Knock Sensor code. Got it ordered, hopefully it fixes this problem and my fuel mileage.

 

i dont know man, bad knock sensor wouldnt even let you start the car

 

Huh?

A bad knock sensor will cause the car to run rough. It will start though.

 

+1

You can still drive the car with a bad knock sensor. The engine will knock loudly and run very rough but won't stop the engine from turning over.

 

A bad knock sensor doesn't make the engine knock more...it just can't detect it when it really does have knock, and it falsely detects knocking...then the ecu pulls timing.

 

Knock Sensor will not make your engine run rough or effect idle in any way. It will effect some performance and MPG.

To the OP - You have a misfire and being you feel it more under load in gear, the jump or accelerating hesitation it points to a weak spark.

You have a coil that's failing.

 

If the ecu pulls timing won't the car run like poop? That's what I meant by running rough.

 

Naw, NJ is right man. U will lose a lil perfromance and MPG if using inferior gas.

Jus use 93 and u wont notice it all.

Bad knock sensor will not cause hard starts or hesitation. Thats more of a misfire or air issue.

I wd clean TB , MAF and grounds. test coils. Check plugs.

 

It just seems odd because it's completely random. It will run fine for days then will buck under 1700rpm (and only under 1700rpm) for a day and it'll be fine again. It also seems to go away after hard acceleration.

 

So I originally had a cylinder 5 misfire code P03005, I replaced the coil pack on that cylinder and it seemed to fix the problem, but it's progressively gotten worse again to the point that it threw another CEL today for P0300 Random Misfire. I drove it the 30 miles home after getting the codes pulled and after about 10 miles it ran fine again so I'm not sure what the problem is, but I'm wondering if a bad fuel filter may cause these symptoms? Other than that I'm at a loss as to the problem.

 

Pull the injector on that cylinder and swop it for another cylinder, see if the fault code follows it.

 

I replaced the Fuel Filter and cleaned the MAF sensor with MAF safe cleaner on saturday and so far it's running perfectly, so I'm hoping that my problem is resolved. I'd like to thank the people who've helped me with it as this is my first modern injected car, all I've owned previously were classics with old school V8's, and I really had no idea where to start.

 

Have you done a tuneup?

 

Yeah, new plugs, oil, air and fuel filters, and seafoamed the fuel system and top end.