Jerky Acceleration

[BryanGrigsby]

My 240 has recently had some acceleration problems.

I thought at first it was the clutch but the more I thought about it, it didn't seem to make sense.

From idle to about 3000 rpm the acceleration is real inconsistent, jerky, and unsmooth unless I feed it alot of gas.

It doesn't seem to be a slipping clutch b/c the rpm wont rev up without accelerating the car.

My thought is something to do with the throttle body? Or maybe some sort of ignition problem?

Any insight would appreciated.

[S13 240SX]

heh good luck with the fix... ihave the same problem and done a ton of things to try to fix it...and nothing.. if you find a fix.. let me know...

i did o2 seonsro, i did coolant temp, i did new intake filter, sparyed carb cleaner in the mafs and throttle body.

[oki_bum]

have you checked the fuel injectors?

[S13 240SX]

well for me.. my injectors should be fine because i just had to replace all of them cuz 3 of them leaked and i replaced them months ago when it happend but ever since that my car has not been the same with the power and revs.

[Arrow]

take a look at this link zer...age=1 I had some major issues and the end result was an ignition / wiring problem... but there are so many things that can effect acceleration that you'd have to provide us w/ more info as to what you've done. feel free to look at my thread and see what NISTECH said to me and everything...
Modified by Arrow at 5:10 PM 5/9/2006

[jes_96]

I had a similar problem. Changed out the cap & rotor and all is well. Turns out two of the contactors in the cap were severely corroded and the rotor contactor was mildly corroded. Don't know if this could be your problem, but it's such an inexpensive item to rule out that it's quite worth the time and the couple bucks.

[Jiggyfry]

i have the same problem as mentioned above. I have replaced the spark plugs, wires, dist. cap and rotor and have ordered the both coolant temp sensors since all this needed changing. Still have the problem but its less noticeable now. Ill know more when both coolant temp sensors get here.

[x3whlmotion240sx]

thats funny i had a altma come intoday i think it was a 93 but it was the dohc ka24. but same problem....but it was the maf+a vac hose that came off

[ddgsxr504]

Since you have an S14 I am going to have to say it's most likely a faulty MAF. They do tend to go bad with age and I had the exact same problem that you are describing. Now the bad news is that the only place you can get one is...

A. JunkyardB. EBAYC. Friend or other hookupD. Dealer (you don't want to end up here as a new MAF is over $400

[Jiggyfry]

I have this acceleration prob too but mine is a '91 s13. I also notice the jerkiness comes on from aboot 1000rpm and stops around 3200rpms. This problem is driving me absolutely nuts! All i have left to do to try and get rid of it is an injector cleaning and new coolant temp sensors.

Just got the 2 temp sensors in today, will install and see if this helps. Anyone have any ideas????

[9240sx]

Do some new spark plugs with the right size gap,Fuel filter,Cap & Rotor,New air filter......All this will help and sould fix your problem.

[Jiggyfry]

Have done all that recently, still the problem persists. I also forgot to mention that at idle i notice a slight stumble but it is slight. Its pouring rain right now, just waiting for a break in the weather to change those temp sensors.

[Jiggyfry]

What aboot a coil going bad? Any possibility that it could be on its way out? Or would a somewhat faulty coil make its presence known throughout the entire rpm range?This problem has me goin crazy. I also know for a fact that the original pcv has never been touched. EVER. Gonna have to check that out too.

[S14toRPS13]

On my previous S14, it was the MAF sensor that was the problem. Instead of spending 500 for a stupid MAF, I spent 3500 for a SR. Gotta capitalize on these oportunities.

[ddgsxr504]

Do some new spark plugs with the right size gap,Fuel filter,Cap & Rotor,New air filter......All this will help and sould fix your problem.

Way to go master mechanic

[BryanGrigsby]

Well this is all just ****ing great.

Stoooped motor.

I wonder if I coudn't get a MAf out of a mustang or something?

Dont they do that when guys pop turbos on a KA?

Im going off of memory here...cant remember.
Modified by BryanGrigsby at 2:02 PM 5/20/2006

[9240sx]

Way to go master mechanic

Thanks alot Sh*tHill Hope you like my master mechanic skills

What the hell was that for??

[Jiggyfry]

dont wanna thread jack here but i installed my both coolant temp sensors last night. NOticed a gain in the lower rpm range and seems like the jerkiness is gone, will have to drive more to be sure. I definetly still have the slight stumble at idle though. As for a MAF sensor being faulty, isnt there someway of testing it? It is hooked up to my safc2 anf the airflow numbers seem to be fine, wouldnt they be off if the maf was at fault? If i knew someone else with the same car id borrow their maf and try it out in my car, but i don't.

[OldmanPurdy]

Your problem probally isn't a MAFS related. Going by personal experience when a MAFS goes bad you will really notice it, My car was farting and spitting fire out the pipes like mad when mine went and the plugs were soot black. If you want to check the mafs just to be sure you need a multimeter and have to do a simple procedure that has slipped my mind, the guys in the Nissan online mechanic section can help with that.

[VinceSez]

I had a similar problem... I found out that I had rust in my fuel, which was killing my fuel pressure. I went to a shop and had them pump out all the rust out of my fuel, as well as replace my fuel pump, and I was good to go.

[S13Coupe]

My car was having similar syptoms, and it turned out that my fuel pump was crapping out on me. Not sure if you have checked the fuel pressure, but mine was running about 10-15 psi low and it made the car kinda jumpy on acceleration. Changed my fuel pump and everything was just peachy.

[MikeMurphy]

typical coolant temp. sensor problem on the dyno

[Jiggyfry]

Thanks for the awsome dyno graph. Thats exactly what i was feeling while accelerating! The jerkiness is more or less gone. I guess my next step is too test fuel pressure and see if its up to spec. Maybe ill pick up a new fuel system since my Ka is gonna be turbo'd eventually.

[Jiggyfry]

OK, so i spent a good hour driving the car last night, and i noticed something strange. My fuel pump primed like it should but aboot 1 min after priming it started to groan and whine for a good 2 mins, then went away. Ive heard that this noise indicates a straining fuel pump, is this assumption correct? I'm thinking this is the final peice to my 240's puzzle! If anyone has some info please let me know as this problem has persisted since I took the car out of winter storage! Thanks in advance!

[BryanGrigsby]

dont wanna thread jack here ...

Thread Jacker....

Anyways, it was the ****ing spark plugs. Never ever put Bosch Platinums in your KA24DE.

I didn't know this before, but now I do.

And that was it. I didnt even change the wires, distributor, or rotor button, though I will in the future.

Hooray for me.

[tonynalli]

its your fuel pump...go ahead and get a warlboro...

[ddgsxr504]

Thanks alot Sh*tHill Hope you like my master mechanic skills What the hell was that for??

Instead of trying to figure out what the problem is you would rather advise the guy to spend money and buy of alot of parts that probably don't need replacing!

Anyways, it was the ****ing spark plugs. Never ever put Bosch Platinums in your KA24DE.

Urban Legend

I have been running Bosch single prong platinums in my S14 for over 5 years with no problems.... I think that maybe your plugs were in need of replacing vice there being a problem with the name brand.

Unless you are boosting Bosch platinums are fine for a NA KA.