I have 120k on my car, its been serviced completely according to Nissan specs for 120k miles... lets say its been a 900 miles since the service...
For the past week, the car has developed a really annoying jerking motion when I'm driving... more pronounced at lower speeds... its like as if the fuel gets cutoff 5 times in a row within 10 seconds.. but the RPM doesnt go down or anything (it stays stable) causing the car to lurch back 'n' forth

What could the problem be? Are the spark plugs clogged? It cant be, because they were replaced with NKT (?) brand (i know its not Bosch).
Dont laugh, but all I can tell you is that I made sure that 99% of what could be serviced/replaced was done so, not more than 1K miles earlier, so i dont understand.

Secondly, I have the Quietstop pads put in the front and new rotors too.. but already i feel as if they are spongy and as if they have lost a lot of their bite? Am i imagining, or is it "normal" after bedding them in or sthg? And I never brake hard, extremely rarely.. i'll downshift or give enough distance

Your help and advice are appreciated,

 

Sounds like your car is bucking. Since the plugs were just replaced recently, perhaps one of the coils is not seated properly... Did a dealer do the 120k service?

Is the CEL on? If yes, what are the codes.

Your brakes might need flushing/bleeding. It sounds like there might be some air in the system.

 

It wasnt done at the dealer but another chain that I trust. Ther service done was what nissan recommends at 120k.
The CEL is not on, but it has been on in the past, and then the light goes away after a week. its been 6 weeks or more since it was on, i didnt get it checked out. How do i tell what the codes are? Do I HAVE to take it to a dealer to get the reason for the light?

Thanks,

 

Read the ECU stickies - when the light comes on, retrieve the codes and post back.

 

NJ,
The light isnt on, so i'm not sure if i can read it...
This has probably been covered before, but since it may help someone in diagnosing my problem, sometimes, when I'm idling at a light, the RPMs fall ery low, literally at 0.5K (sometimes at 750rpms)... but again, remain stable (and dont vary/jump)

Thanks again,

 

If the light isn't on you can't retrieve any codes.

It sounds like a misfire type problem. Are you use the mechanic used NGK plugs?

 

I would say a faulty coil, or a pcv valve.

 

Im having the same issues! Now upon cold starts the car stalls. Starting the second time it fires right up. I push the clutch in and the rpm's go up when changing gears.

 

Thanks for all the suggestions re: what the cause may be
i.e. coilovers, PCV valve (?) or the plugs themselves -> definitely suggest these to the garage

Another thing i noticed is that its more likely to happen when i'm giving it some gas.. though it happens at constant speeds too

Farooq

 

Definitely sounds like one or more bad coils to me.

 

coilpacks not coilovers!

 

So I got the garage (no-dealer) to read the codes, says its the knock sensor which will set me back around $240CDN, or $200 USD .. and 2 - 3 hours of labour...

could that be causing the problem?
Says coilpacks are around $150 CDN each (seems steep) - but not the likely culprit..

any thoughts?

thanks,

 

Knock sensor will not cause the behavior you are describing. If this started right after the plugs were replaced, you may want to find out exactly what brand/part # plugs were used by the shop.

I would also look into replacing the coils. You can buy them cheaper online (USD 60 each) and do the work yourself in 1 hour or less.

 

they shouldnt charge you 2-3 hours of labor for the knock sensor i did mine in 15 minutes tell them they dont need to take off the intake manifold to get to it. they are trying to rip u off

 

1 - The problem started about 1,000 miles after full service or about 1 month or more... all i know about the plugs is that they were NGKs

2 - Where can i buy the coils online? and Why are they so much cheaper - are they "refurbished"? Also, how difficult would the work be?

thanks,

 

The fact that they will need to take the intake manifold off is exactly what the guys showed me they would have to do... how did you do it? Maybe I can indicate to them?

Also, CAN it be the KS causing the "bucking/lurching" motion? (the OBD indicated the KS was no longer good)

thanks,

 

The KS will not cause the lurching.

The coils are cheaper online because there are online parts dealers who buy in bulk and can offer wholesale prices.
e.g. courtesyparts.com, jrnissanparts.com, midwaypartsteam.com.

The mechanic who replaced your plugs should be able to replace all 6 coil packs in 1/2 hour.

The knock sensor can be reached with a universal 12mm socket and a 12" or longer extension. Read the stickies for the procedure - and print it out and take it to your mechanic. I would resolve the hesistation issue first - because the KS OBD code may be there as an artifact rather than the cause.

 

yea all u need is a universal and an extention...thats probably what they would do anyway then tell u they had to take off the intake manifold

 

Thanks everyone!
Gonna call off my appointment tomorrow at the garage and look this up in more detail in the stickies.

Reading the other post re: PCV valve, maybe i'll get that changed too.

So... just to be clear, is it the general consensus that it may not be the KS after all? If not, then it is the coil pack?

How can i tell what it is (with or without the mechanic's help/tools)

thanks for all the insight

 

from what ive gathered with the knock sensor it would seriously retard timing and make the car sluggish.

also check around there is a post on cleaning the coils if you feel up to it, doesnt seem hard at all, but if that is what they say it is, i would try that prior to replacing, good luck.

 

Replace the Throttle Position sensor.

 

I am having same problem on 99 maxia. About ready to buy an TPS, cost 100$. Did you fix your problem?